The uTracer in Forums:

Deel 1 Part 1 Teil 1 1ère Partie

To be continued....

27th of March 2017, Dominique Prost’s from Audiotronik reports his uTracer ready for use!

Hi Ronald, Hi Marie José

Utracer is finished, the tube tester started without problem after I built the kit, it is in the box and began to make his first measures...
Now I have to domesticate this very complete software.
Thank you for having designed this realization, I stay connected to your web site to be informed about some updates...

here is some pictures for testimonial

Bien Cordialement.


11th of February 2017, Jesper Karlsson made a thread about the construction of his uTracer on a Swedish forum!

Hi there Ronald!

A while back you asked for build pics and thus..this mail.

I´ve made a thread as far as my build on a local forum,to us,where i describe in depth how the thing has been put together.

As you can see the actual box isn´t quite done and ready for service yet but...getting there.
Last thing i did last night before heading home was to tear the thing apart and hand that box its final layer of mahogany taint. This will now be followed by some clear coat.
The sockets I’ve opted to install steady state into the faceplate are for the,to me,most common types tested like EL-34/6L6 et al...6SL7...6SN7 turn EF-86...ECC-83 and EL-84.
For other tubes i´ve ordered so called saver sockets from Asia that i plan to take apart and simply repin to whatever is needed, down to even replacing sockets to be able to test EL-12 and what not down that path.

Sincerly; Jesper Karlsson

11th of February 2017, Carl Peter’s uTracer is finished and he is very pleased with it!

Hi again.

I have built the uTracer with no problems, it worked from the first time i switched it on. I think the construction manual and the test steps in the construction process is very good.

As You can see on my photos i have put the uTracer in a used box from another equipment, and I haven't done a lot for the finish. I was in a little hurry to get it working, and i don't think the finish will change in the future. As long as i works it is fine for me :-) I have made a plastic plate with the sockets i use at the moment, in the future I plan to make another plates with another sockets.

In the beginning I occasionally had some strange readings, I think it was due to some oscillations. When I put ferrite rings on the wires from the print to the banana plugs on the front the problem disappeared.

I am very satisfied with the uTracer, it works fine and is easy to use.

Kind regards
Carl Peter

11th of February 2017, After a few hiccups Mika Koskimäki’s uTracer is up and running!


Many thanks for the support with my utracer project.
Had some challenges but everything went great after you found my mixup with the op amps.
I managed to build a case for the tracer. Not so nice but practical. Effectively I've been able to measure every tube in my collection. Very powerful tool indeed!.
Here is couple of pictures of my tracer :)

Thanks again,
Mika Koskimäki

27th of January 2017, Jean Huet finished his uTracer in record time and is very happy with the result. More pictures to come!

Dear Marie José, dear Ronald,

Construction finished, calibration done.
Everything went like a charm!

I will now clean up my mess, have a rest (I need it!) and continue tomorrow with my first tests with a real tube and get experience with the µTracer during the coming days.
In the meantime, I will think about the final design of my tube tester. As soon it is nicely packed, I will send you pictures (this will take more time!!!).

Many thanks for your kindness, and this great kit!

Kind regards.


25th of January 2017, Blaze Pawlak’s father made a fantastic project of his uTracer!

Hi Roland,

My dad finally assembled the kit I’ve ordered from you a couple of months ago (sometime in November, 2016) and I have to say that he can't find enough words to explain how much he admires your work and craft. The kit is just a brilliant piece of engineering both hardware and software wise. And the manual, oh the manual… I wish all products came with such detailed instructions that take one step by step through the assembly process and on top of that act as a check list. Big thumbs up for that!

Anyways, here it is. I’m attaching some pictures my dad took of the final product. It’s a custom case in old kick ass briefcase and the software is running in Wine on a Mac. Hardware got calibrated according to your instructions and we’re getting great results here. First few tubes that we tested revealed their true characteristics. Brilliant! Now I’m pretty sure my dad will be able to make better informed decisions about which tubes to use in his audiophile products. Everything to better quality and make recipients of his hardware even more satisfied.

You’re welcome to use the pictures on your site if you’d like. In case you’ve got any questions, don’t hesitate to drop me a line, I’ll be more than happy to get back to you :-)

Cheers and all the best Roland! Great work – that’s engineer talking to engineer.

22nd of January 2017, Félix Menéndez and José Ramón report on their adventures with the uTracer!

Muy buenos días, María-Jesús, Ronald!

Hope we are not too late in forwarding you our last uTracer version, bought autumn 2013!

Well, this is our third version. We started following your own build example. Then we developed a second, full of sockets. Soon we found that, for our particular usage of the tester (mainly in restoring, servicing vintage gear, as a hobby, of course, we are "boatanchors"), it was a bit boring the jumper-changing routine. So we ended up with this "cost-no-object" version with rotary thumb switches and only the most used tube sockets in our case, plus external heating (a filament transformer build for that application following a Metrix scale).
Everything in a professional looking metal carrying case, stainless steel front panel and laser text engravings.
First problem after the front panel was cut and engraved: we maintained the "electrode-selects-pin" approach of the jumper selection mode. But this approach, with rotary switches, enables you to make a nice short by mistake in the filament circuit, for example... No good practice...
We had to reverse our selection mode to "pin-selects-electrode" (Metrix style). So, the lettering is no more valid... a pity.
No big deal, though. Anyway, you had to resort to the switch numbering scheme in the booklet we are building for each tube class.
Enclosed a couple of photographs of the machine.
And congratulations for a very useful test equipment!

Kind regards,
José Ramón and Félix

9th of January 2017, Mikhail Stolpner’s uTracer is in “Philips Blue” !

Hi Ronald,

I am super excited to hear that you keep working on improving the uTracer. It's a very helpful tool.

Attached are a couple of images of my build. I did not go for a look and it's a super basic build. Please, let me know if you want photos of the inside, happy to take them.

The most significant limitation for me is Vg. I would like to measure tubes like 6S33S. I would need to go between 30V and at least 100V with Vg. Do you think I can include a floating voltage source of 30-50V between the greed the uTraces?

Increasing a max Ia to about 300mA or even 500mA would be very helpful too.

Thank you very much!

7th of January 2017, Ebert Warmerdam turned his uTracer into a piece of art!

Hello Marie-José & Ronald,

Way back in 2014 I purchased your uTracer kit. As a guitar player I wanted to understand my amplifier more with the kit and hoped it could help me bring down repair time because every time I brought my amp for repair it was gone for a while and always came back with the remark that the cause of the problem had been a bad tube. The next step was designing a box to put it all in. And that took some time because I didn't have a lot of spare time. Meanwhile the uTracer3+ kit came out. I bought it and put it aside to fit it in when I would pickup the project again.
In 2015 a friend of my brought me an old toolbox which he had found in France. I decided that this box would start a new life as the home of my uTracer. The plan was to put a modern front panel in this old toolbox, symbolizing "old meets new". Just like the old tube technique encounters the modern uTracer.
Next step therefore was to design a front panel and it took me to 2016 before I had the time to do so. For the front panel I studied the designs already present on your website and implemented my wishes in the free Front Panel Designer of Schaeffer AG (Germany) which I had downloaded from the internet. So next to physics I also learned a lot of computer design in the process!
The sockets I used are octal and noval, which suffice for the use with guitar amps, but without any problem I can connect any other socket type external if necessary in the future. A Calibration Mode, Continuous Mode, an External Low Voltage Supply and a direct connection to the power of the uTracer can be found on the front panel next to the more obvious things as a 230VAC socket, an on/off switch, USB socket and two fuse holders. The uTracer was named "Warmerdamps Buizentester" and another friend of mine made an "aged" name plate for me in the same old style as the toolbox and painted the black letters "uTracer" on the lid. On the inside of the lid was already a storage place present presumably for spare parts where I can put my USB wire, power wire and banana plug wires.
During the entire build of the uTracer I learned a lot about the inside of my guitar amp as I had hoped I would do when I purchase your kit. It even gave me enough confidence to build me my own amp to suit my guitar: 5F1 style Fender amp with in the tube compartment a 12AX7, a 6V6 and a 5Y3. And after getting the taste of this I also made me a 6G15 style Fender tube reverb tank to make things complete. The tube reverb tank has got a 12AX7, a 12AT7 and a 6V6 in the tube compartment. So your uTracer kit has had quit some impact on the gear I'm playing with. I really can't thank you enough for making your kit available for those who have an interest in electron tubes!
I will enclose a photograph in this mail and send some others separately, just in case your server will refuse more than one picture as an attachment.

Kind regards,

Ebert Warmerdam
The Netherlands

6th of January 2017, Mark Lacas found an unbuilt uTracer on eBay and he is extremely pleased with it!

I am a musician, audio engineer and tube amp designer, and was delighted when I discovered that you had created the uTracer. I had previously been using a TV-7/DU and Hickok 739A, but found them, and the prototypes I made, very time consuming and limited for characterizing tubes, and testing my designs.

Your construction manual was very easy to follow, and I was able to get my uTracer built, working, and calibrated in one day. It took another few days to complete the case and wiring. The uTracer is a welcome addition to my workshop.

I am using your software on Windows XP 64bit, running in a VBox virtual machine on my MacBook Pro 17” running Yosemite OS. After a bit of fiddling to get the drivers in the proper places in windows, everything worked a charm.

I have also enclosed a photo of my latest amp build, a 50 watt/channel hifi amplifier using 6SN7s and KT88s that I call the PSW-100. Ive also enclosed a photo of my laboratory. . . both of which are highly improved by your efforts.

Thanks for creating such a fast and comprehensive tool to aid in my work and play. Over 800 of my friends have been avidly following my progress on Facebook as I have pushed the project forward to each stage of completion.


29th of December 2016, Roberto Gubellini made his own version of the uTracer!

In pictures first run of my uTracer
(it is now time to look for a worthy container).

Thank you

best regards
Roberto Gubellini

28th of December 2016, Apparently Charles Bueche is using his Christmas holiday to finish his uTracer!

Dear Ronald,

I have studied electronics during my studies between 1981 and 1988, and then I left that world for computers. I'm now back in tube-audio so I needed some tools, including your fantastic tracer. I'm sailing during the spring-summer-autumn, this is why getting my uTracer in its box took almost one year. As I was interrupted by having to race 10 regattas in 2016, I needed two winters to build the tracer, in fact :-)

I attached two pics of the uTracer in its box (Hammond 1456KK4BKBU from Mouser). I used the USB-to-RS232 converter with an USB socket on the left of the box (not visible on the pics). I'm mostly interested in audio tubes that dictated my selection of sockets. I followed your excellent guide and here I am, first measurement of a very old ECC82 I had in basement. Now I need to dig out my books and archives and better understand how tubes work so I can understand what these nice curves means :-)

So your stats can be updated with one new uTracer in Switzerland :-) I wish you and your family a great year 2017, and thanks again for your work!


26th of December 2016, Wolfgang Thiel spent his Christmas holiday finishing his uTracer!

Hi Ronald and Marie-José

I just want to let you know that I completed my uTracer (well almost) and had no problems assembling it thanks to your excellent construction manual. Such high standard. I opted for a compact version which will fit in a 3ru 19" rack. Only two Valve sockets installed but have allowed for an adapter to be fitted with different sockets when needed. Working now through the manual to familiarize myself with the many options.


7th of December 2016, Ted Walker’s uTracer is up and running!

Hi Ronald and Marie-Jose,

A photo of my uTracer3+ up and running, no hitches, thank to your well organized assembly manual. Building was a real treat, using even more so.

Thanks again for making this jewel possible!
Ted Walker KB5OF
Euless, Texas

29th of November 2016, Lars Ewald’s uTracer is straightforward and effective!

Hi Ronald and family,

First off all thank you for all the effort you put into this great project.
As promised a couple of pictures of my way of assembling the UTracer.
I have added 3 sockets. The first is for EL34, KT88 etc. The next socket is for EL84 etc. and the final socket is for 12AU7 etc. For other tubes I will make a socket converters.
On the top a power switch and an external Heater supply switch is available. I chose to use USB to Uart converter cable for the laptop connection and an external Laptop PSU.

23rd of November 2016, Gerardo Nardozza’s uTracer has come to life showing that language barriers are no obstacle!

Hi Ronald,

Sorry if I didn't write before, but unfortunately I don't speak English, so I always have to ask somebody's help.
I have finished my uTracer but it still needs its final cabinet. As regards the experience it was positive, I didn't have any particular problems even if the assembly was quite long and engaging. I find the whole project interesting and very useful, I think you really did a great job.
I'm sending you some photos but in the future I hope to be able to send you some more picks of the completed kit.
I'll be happy to keep in contact and be informed about further developments.

Gerardo Nardozza (Italy)

9th of November 2016, Mladen Knezevic and Zdravko Kristic from Croatia turned their uTracer into a nostalgic work of art!

Hi Marie Jose and Ronald…

As you already know I have bought several months ago uTracer kit that has been delivered safely to Croatia…

After occasional work finely a friend of mine, mr. Zdravko Kristic and me, managed to get things done. uTracer is working perfectly from the very start and without any problems. It is fitted in wooden modified box from local Bauhaus store, which give a vintage look to the device.

Now we have to learn how to unleash full potential of this useful tool but this is another story.

I am sending you some photos of our uTracer.

Wishing you all the best I am sending you warm wishes from town of Rijeka, Croatia.

Mladen Knezevic & Zdravko Kristic

8th of November 2016, Gabriele Carnevali’s uTracer has been optimized for guitar amplifier tubes!

Dear Ronald.

I completed uTracer assembly several months ago and I'm happily using it. It seems working well.

I did not write you yet because I would like to complete it with some look improvements. Unfortunatelly I have no time for these tasks, so I think that my uTracer will look as photos all its life long...I just need octal and noval bases at the moment because I work with guitar amps and they only use few kinds of valves.

In one of the pictures you will see that your nice postcard from Holland has a special place in my lab!

I hope for you the best. You really do so much for our community!


Gabriele Carnevali

Fabriano (AN)


2nd of November 2016, Robert Culver used the uTracer to restore and old Tek 454 Scope to its full glory!

Read more about this beautiful project on: EEVblog Electronics Community Forum

Dear Ronald,

I thought I would let you know your uTracer helped me repair an old Tek 545 to full working order, it found 4 of the 100 or so tubes were not working.
I used a similar socket interface to you.
Photos after much cleaning, repair, repainting and re-adjustment of the old Tek.

Many thanks
Robert Culver

1st of November 2016, Thomas Rehm’s version comes close to my dream uTracer!

Hi Ronald,

I successfully completed my uTracer in April this year. It took me quite some time to find the right cabinet for it. Finally I decided to use an old wooden filing box which just fitted the size of the uTracer PCB. It was a bit tricky to find a layout so that the socket wiring, plugs and the big old switch on the front panel did not intersect with the big electrolytic capacitors and other components of the uTracer.
The result of this work is a very nice retro-style uTracer which does a reliable job tracing the tubes of my old radios and amplifiers.
Many thanks to you and your wife for making a kit available which enables an electronic hobbyist like me to build such a great tool.

Thomas Rehm

25th of October 2016, Robert Waldow’s working place looks like a real lab environment!

Hello Marie-Jose,

Some weeks ago but the uTracer is now running.

Thank you for this great kit with a magnified description. You have done e really got job for a least a fair price for as tube-maniac’s.
Also the GUI is great and works very fine.
Thank you for this smart tube kit.

Kind regards

Robert Waldow

24th of October 2016, Michikazu from Japan turned his uTracer into a handy instrument!

Dear Marie-José.

uTracer was put in a box of My holdings.
The socket was made wiring of 6L6.
I can measure it without adapters.
It's possible to supply a heater from external supply.
The meter which stuck to the body indicates the heater voltage, the plate voltage, the screen voltage, the bias voltage and Cathodic current.
But it's ordinary.
Small adapter I made.
It's can measured twin triode one or another one by the switch.
I'm playing every day with this.
You offer me something good, and I rejoice. And a picture is attached.
Thank you very much.
I hope to see you next time.


13th of October 2016, Erik de Best made a quick and dirty but very functional case!

Dear Marie-José and Ronald,

I finished my utracer a long time ago, and finally managed to make some (bad) pictures! I am very happy with it, I couldn’t do half of my projects without it!

I put the unit in a plastic container, with a second container on top to hold all the wires, power adapter, USB to RS232.

For my amplifier projects I use a lot of Phoenix PCB terminals, which I slightly modify as you can see in this pictures. That way my amplifiers are mostly “screwed together” (here are some pictures So I just use these tube sockets to test my valves, connecting them with the alligator clips to the utracer.

Feel free to post this on your website!


11th of October 2016, Guido Lindges has a workshop at home where he can make a beautiful case like this …. I am jealous!

Dear Marie-José, Ronald,

last Weekend I finished my µTracer and measured the first Tube (an old EL 84). I am very pleased with the result!

As I have a small carpentry in my house, I decided to build an old fashioned Plywood case (like Funke and Neuberger). The chassis was built of a 4mm Aluminum plate, completely drilled and painted in my workshop. I opted for linear regulated power suplies for both, the µTracer and the heating. (Sorry, but I am old fashioned when it comes to power supplies, because I build tube amps for hifi). The heating supply can deliver up 12,6V @ 4A, higher values will be heated with my "big" external power supplies.

I would like to thank you both for this outstanding kit! The documentation is a fun to work with. Everything worked fine and the software (GUI) is very intuitive.

best wishes, groetjes

Guido Lindges

4th of October 2016, Simon Huser sent me an extensive and enthusiastic email!

I finished my uTracer. The building instructions were great and user friendly. Everything worked without any problem.

I added the 330uH coil, the ferrite beads and the fuses. As my dedicated laptop PSU was heating quite a lot (less than the idle LM337), I didn't put it inside the enclosure. I even re-used its ferrite bead. I bought a sort of mini-banana plugs that could be plugged together, so it was easier&cheaper. I used my PCB prototyping CNC to mill a grey covered black plastic-material, and then taped it on the enclosure.

Perhaps you remember that I design ultra-linear (UL) guitar amplifiers. Those contain the smallest amount of component possible. It's cheaper, so I could afford more robust components for the same price. I only design with the following tubes: ECC83 (9€) and EL34 (12.5€). They are cheap and sound great. 1xECC83+2xEL34 is enough to have >30W speaker output in UL PP. I put only the 8 and 9 pins sockets, because other-sockets tubes are too weak or too expensive to fit my designs.

Here are some graphs of a test EL84 and its resulting spice model. The Ia=UL(Ua,k) and Ia=UL(Ua,Ug) curves are helping the designer to quickly determine the best bias point for the UL operation. The Ia=UL(Ua,k) could be produced using the "Keep Plot" feature. Being able to have accurate spice model of my tubes in a quick&easy way is a big improvement for my designs.

Thanks for everything!
Simon Huser

9th of September 2016, Carey Gruszie’s uTracer is no-nonsense but very effective.

Hey Ronald,

Just thought I would send you some photos of my completed u tracer. Nothing fancy about the build, will be mainly using if for guitar amp tubes. Anyway. All went together pretty well. Had a few issues that I rectified and it does well. The external heater supply is a good addition. I measured the heater voltage with a true RMS meter and was measuring 5.4 volts for the heaters since it is a pulse current source I knew it would be difficult to set an accurate value so using the external heater circuit helps out with it. Anyway I'll attach a few pictures and maybe someday I'll make a nicer chassis for it someday.

10th of August 2016, Jan and Kryštof Soldán turned their uTracer into a very nice and compact instrument. Their whole instrument collection is pretty impressive by the way!

Dear Ronald and Marie-José.

I would like to inform you, that another uTracer was born in Czech Republic.
Every section was smooth and work on the first switch on.
Your work is outstanding.
Thank you very much for all.


26th of July 2016, Filip van Kenhoven built his uTracer on perfboard an he and his son Michiel made a beautiful project out of it!

Hi Ronald,

First of all my congratulations for this fantastic engineering project !
Here are some pictures of my uTracer, you’ve seen it working already on the NVHR radiofair last December.

I started to build the uTracer in December 2013 and it was working around March 2014. I decided to buy the programmed PIC processor and to assemble the circuit on perfboard step by step because I have a large stock of components. The “difficult” parts were obtained from the free samples service of TI. It was quite an experience and a challenge to start from scratch and complete it on perfboard – more driven by nostalgic feelings to assemble a project in this way after many years. However, after all, I would recommend the complete kit …

The uTracer works perfect and is mainly used to test tubes for my old radio’s. Up till now I have not upgraded to the 400 V version, 300 V is enough for the tubes I work with.

I also added the Bluetooth interface described by Mark in the Google group (Serial Module HC-06-D RS232/ TTL with EDR) which works perfect. With a switch I can choose between the standard RS232 interface or the BT.

Kind Regards,

Filip Van Kenhove

Filip’s son Michiel (15) has no particular interest in tubes, but appears to be quite a wizard in programming, Java, apps etc.
In his spare time a wrote a “quick test”app for Anrdoid that communicates through the Bluetooth interface his father uses to communicate with the uTracer.
The calibration values have to be entered once after which they are saved.
Michiel is currently fine tuning the app and when it is finished he will make it available on Google play store!
Michiel even made a beautiful YouTube movie of the app from which I have extracted a few stills. Enjoy!

17th of July 2016, Bo Johansson made a very nice uTracer with the thumbwheel switch from a scrapped AVO MKIII!

Dear Roland,

It was a while ago I bought the uTracer kit from you!
I have updated it to 400V, furthermore, I have taken the thumbwheel switches from a scrapped AVO MkIII and fitted it to my uTracer! Works perfectly!
And thank you for the excellent job you and your family have put into the project!

Wish you and your family, a really nice holiday!

Best regards

Bo Johansson


17th of July 2016, Grahame Marsh’s uTracer looks like a work of art and he is sharing his dxf file with us!

Hi Ron,

I'm exceptionally pleased with uTracer. I put the board inside a laser cut and engraved acrylic sandwich. I put the fuses and additional inductors on a homemade PCB inside the sandwich. I just plug a valve base in that hangs on banana plugs. I intend to mount the bases on their own acrylic sandwich but I've not done that yet. The acrylic master is enclosed as a dxf file (the spare space is filled up with components to make a B14G base). All very quick and simple but safer than playing with a bare board.

I suppose you can say I'm "experienced" in electronics and had no problem with assembly, testing or calibration. At the time I built your kit up I was developing my own kit for an Arduino Due base CRT clock. I learned a lot from your packaging method, manual design and style.

On another, CRT related, matter I am just building a CRT tester capable of testing CRTs that require up to 4kV to operate (and an extension board to 10kV). I was going to post a link on your forum to the webpage where I will give details of the design and kit that should be available. So not a competitor to your utracer and specifically for CRTs. Is this ok with you?

Our holiday this year was two weeks walking in the south of Spain and then two weeks with our feet up in a letting cottage near Bergerac, France.

Cheers Grahame
Highlands Scotland

The dxf file of Grahame’s case can be downloaded here.
The beautiful acrylic plates were ordered from ZAP! creatives.

27th of June 2016, Sven Stalbovs is happy with his uTracer!

Hi, Ronald.

Wanted just thank you for your great engineering piece of work. The uTracer is every EURO worth I spent.
Did test some of my tubes like EL34, 12AX7 and last not least the GU50. I am very pleased to get really the diagrams for engineering judgment.
Attached some pics. The cases are recycled thus not perfect but useful.

Kind regards

Sven Stalbovs

10th of June 2016, Chris Chang from Taiwan finished his uTracer and is spreading the news in his country!

Hi Ronald,

Attached are some photos of the utracer I built. I plan to mount a couple volt-meters on the front panel. When I built it I had one goal in mind: Building the smallest utracer that can take as many sockets as possible. I am going to write an article about this cool kit and put it on my blog. Thanks for all the great works.

Chris Chang

View the website of Chris
View the thread on the uTracer on Facebook

16th of May 2016, Anton’s uTracer is ready to test his 20000 tubes! 6th of May 2016, Detlef Kraus finished his very nice uTracer!

Hi Ronald,

now I have it done to change the COM port number to 2 and it’s all at best.
Both uTracers PCB are okay.
The wireless connection from my notebook to uTracer operates with BlueTooth and so I have more space in my motion.
Attached are some pictures of my uTracer3/1.
At the moment I can’t use my uTracer3/2 with the GUI uTmax.
If the measure procedure lasts longer report the GUI a timeout signal from uTracer.
It happens with USB and BlueTooth connection.
That’s all I have to comment in this moment.

Have you and your wife a nice weekend and best regards,


27th of April 2016, Steve Dillon just started the construction of his uTracer and sent me a picture of “the assembly area.” An amazing work spot, I could not resist posting it!

Greeting from Pennsylvania!

The uTracer arrived safely yesterday and I verified the 12.1k resistors are in fact 121k resistors. I will proceed to build with that in mind and not place the incorrect resistors. I look forward to completing the build and putting the uTracer to good use. I will send pictures of the build as I progress and of the completed project. I plan on making my finished uTracer look like an antique 1930's Leeds and Northrup type design made with a wood frame and black panels.

Here is a picture of the assembly area.

All the Best,

27th of April 2016, In true DIY spirit Harald Grabowsky made a fine case from leftover materials!

Hello Ronald and Marie-José!

Boy was it fun to build the uTracer! Excellent documentation and step-by-step construction and test/calibration guidelines made it a very straight forward process. After checking the connections and recalibrating the I(a) and I(s) with a 1% spec resistor, all is working beautifully and the fun can begin.

In true spirit I did not buy a clean case, but opted for the time consuming trials of making a box using some leftover materials. I selected only the 8-pin octal and 9-pin miniature bases for now, for the testing of instrument and audio amplifier tubes such as 12AX/T/U7 series, 5687, and power tubes such as 6L6, 6550, KT-88 etc. There is some space for accommodating another socket should the need arise.

The actual board is securely mounted using brass machine screws and threaded nylon spacers with brass thumb nuts. It is easily removable if needed. I opted for adding a combination of chokes totaling around 340uH, and mounting RFI beads for the heater and fuses on a terminal strip inside the box wall (The RFI beads are underneath the terminal strip and don’t show on the picture) . To save space and keep the heat out, I indeed found an external old laptop supply that works beautifully, I just added a switch and jack. A vent hole to reduce heat buildup inside was added just in case. Incidentally it allows me to see the LEDs inside, an added bonus. At some point the leads will be properly sized, but first it is time to play!

Already I was able to detect issues with some new tubes that were installed to replace supposedly bad tubes in a bass amplifier. The 5-piece new name brand pre-amp tube complement included 2 bad tubes! Then, a new four piece matched pair of name brand 6L6 power tubes included one shorted unit. I found that in many cases, new tubes that are being sold by retailers are not tested before shipping. And, not every vendor is good about returns as they cannot verify a claim of a bad tube. Also, not all instrument amplifier technicians have a tube tester, often recommending replacing all tubes.

So I am very pleased with my new measuring instrument and in retrospect question how I could have done without for so long!

Hartelijke groeten uit California!

Harald Grabowsky

14th of April 2016, Alexander Gurskii from Belarus made his own PCB with excellent results. Compliments!

Hi Ronald!

I'd like to report about success in assembling my uTracer v4 "from scratch"... It passed all tests and calibration procedures (well described in your great manual). So, thank you very much for your great project!

Herewith I'd like to send some pictures as a "report".
First, since your manual has the pictures of pcb, I was able to make pcb file in the Sprint Layout program, using these pictures as a background. The main problem is the impossibity to make metallized holes at home, thus, I slightly modified the pcb, adding several holes for transitions to avoid transitions through pins of the parts. Then I asked my friend Eugene and he prepared the pcb. The pictures of both front and back side of pcb are attached. Not so good-looking as your factory-made pcb-s, but quite acceptable. The transitions then were made simply by soldering little pieces of wires through holes, thus, the "double-sided" pcb was created.

Of course, the soldering of PGA113 was a nightmare...
During the test, 5 issues were located, all of them were caused by the lack of conductivity (bad trace or crack in the transition between sides). These defects sometimes were even invisible, and in some cases I simply wired the end point of the traces on the back side. One can see 4 wires in the final pictures of pcb. Not so beautiful but safe. The 5th issue was bad ground contact of one PGA113, fortunately, far from its package.

The final pictures of pcb are also attached (at the moment, I still didn't remove the rests of soldering flux).
I replaced some parts by similar types, I think it is not so interesting. Finally, I attached the pictures showing the very first use of this device today: the test of the soviet 6P9 pentode (=6AG7), and the test of the soviet 6N9S double triode (=6SL7-GT), as well as the results (plate curves).

And of course, thank you once again for your nice project!!

With best regards,

6th of April 2016, Ferdi Uitenbroek reported his uTracer working. He has plenty of space for more sockets!

Hallo Ronald en Marie-José,

Het project is voltooid. Het is misschien de meest fraaie behuizing, maar ik had deze nog.
Als het nodig kunnen er nog een aantal buisvoeten bij.
Hartelijk dank voor jullie hulp en service, aan het maken heb ik ieder geval prettige uurtjes beleefd.
De foto`s laten de testopstelling zien van een EL84 (overigens geen beste).

Met vriendelijke groet,
Ferdi Uitenbroek

27th of March 2016, Sometimes I stumble on internet over a beautiful built description quite by accident! like this one here

23rd of March 2016, T.Mori from Japan reported his uTracer working.

Kit has been completed.

Please check attached picture, it’s working very well

Thank you.

27th of February 2016, Paul Newman from New Zealand made a splendid portable uTracer!

Hi Ronald and Marie-José,

I’ve just completed construction of my uTracer and am very pleased with how it’s turned out. Your construction manual was really clear to follow and the uTracer worked OK the first time I used it. Attached are some photos.

I mounted the uTracer in a spare aluminium-covered case I had and fitted the RS232 to USB adapter inside the case. I also added an internal auxiliary heater power supply powered from a second laptop power supply which I set up to provide switched voltages of 2.5V, 5V, 6.3V and 12.6V. This also enables me to gradually bring the heaters up to their required voltage when using the auxiliary power supply. I also added the ability to connect an external heater power supply for tubes with high heater current consumption.

There is quite of lot of heat generated inside the case so I added dual 40mm fans to the front panel, one fan to suck air into the case and one to extract the warm air out.

I test mostly audio tubes so hardwired a set of sockets for the most common audio tubes I need to measure and added a second set of sockets that I connect using jumper cables. I also added a life test switch that drops the heater voltages by 10% by switching in extra resistors into the internal auxiliary heater supply circuit.

Thanks for producing such a great kit and also thank you to all the other uTracer constructors for the ideas I got from their photos on your website.

Kind regards

Paul Newman
New Zealand

ps: Paul wrote a description of the auxiliary heater supply he built. You can download it here.

23rd of February 2016, Jim Yates finished his very nice uTracer.

Ronald and Marie-José,

I am beyond impressed with the quality and attention to detail that you put into this kit!
I couldn't be happier with the outcome. Also thanks again for pinpointing the loose solder joint on the inductor in the anode section via email no less which saved me hours of headache.

On to the build: The main idea for the layout and case was taken from Joe Leskovar’s TTT-3 (a work of art). The 3 hardwired socket approach and a mini toggle to switch between triodes, will work for the most common tubes found in guitar amps, which is what I'll be using the tester for primarily.

The face plate is from DataPro in Seattle, another class act. I can’t say enough about the quality and excellent customer service I received from this outfit as well.

On the right side of the case I’ve have a C14 AC power inlet, an on-off switch with LED indicator, and a Switchcraft EHUSBBABX USB B to A going to a Belkin F5U409V1 for the serial conversion.

All housed in a Pelican 1200 knockoff case with a Pelican panel insert adapter for mounting the DataPro faceplate. There's even enough room to expand capabilities in the future if needed.

Thanks for the great experience!

-Jim Yates

16th of February 2016, Allen Gardner from Amgard electronics made a very efficient and logic case around his uTracer!

Hi Ronald,
This is just to say how much I enjoyed building the uTracer. Your documentation is a real joy to follow, it far exceeds that which is supplied with 'commercial' kits.

It took (approximately) one day to build the board, another day to drill & label the case, (one I already had from previously aborted project), and a further day to do the wiring.

I did have a small problem in the early stages, with grid biases at zero producing extremely low anode currents, but thought I'd do a full re-calibration before seeking your help. As you might guess the full re-calibration did the trick and I get perfectly good results now.

I have a lot of fun in front of me getting to grips with the possibilities of the uTracer, and I have a lot of valves in questionable condition to try it with.

In the meantime, I have attached some photographs of my uTracer. As you can see I have opted for quite a simple set of valve bases and layout, but this suits my needs perfectly as I only come across a limited range of valves in my workshop, which is geared up to build, design and repair guitar amplifiers.

Once again, many thanks to you and to Marie-José.

All the best

Allan Gardner

6th of Februari 2016, Jose’s uTracer is very stylish and compact!

Hi Ronald,

The uTracer is working properly. Thanks for solving the problem.

Attached are some pictures.

Best regards for you and Marie José

2nd of Februari 2016, Alex from Germany is certainly happy with his uTracer!

Hello Marie-José and Ronald,

It took a while to build the kit cause I only had a few hours on Sundays. But now I like to inform you that my „raw“ build is finished. It works great!
Thank you for the very well done documentation, it´s bullet proof! All steps have been easily assembled though I do not like this transistor stuff with PCB... :-)

Here are some impressions, but my build is poor compared to the examples on the website. Let´s see what I can do around it in the next time. I think I will design a little box with a few (not too much) tube sockets.

That´s all for now so far.

Many happy greetings from Hannover, Germany.

29th of January 2016, Miloš from the Czech Republic turned a whole pile of components into a very beautiful uTracer!

Hello Marie-José and Ronald,

I’ve finally finished my uTracer. It works and serves very well. I wanted a device like this for a long time. I’m an active musician and a tube amp technician and I really appreaciate uTracer as a great gadget for tube measuring. My design is inspired by another user.

Huge greetings from Brno, Czech Republic!

19th of January 2016, Christoph Bohr finished his uTracer (again) and sent me a nice testimonial!

Hello Ronald.

Finally I found the time to finish up the µTracer ( again ;-). Thank you very much for your great support and patience. The kit is really easy to build, the manual is incredibly detailed and if followed closely step by step it is practically bound to work first time. One can really see the amount of time and effort that went into preparing the kit, this is far better than what you would normally expect from a commercially sold kit. I build the tracer into a small carrying case I happened to have and I added a second 6V supply to choose via a front panel switch for the lower voltage heaters. Went with the banana plugs, switches, imho, make only sense if they are pretty high grade, so patch cords it is ;-) Also makes it easy to interface the µTracer with external gear. Find attached some pictures of the unit, open and closed up as well as the µTracer measuring a TM style triode that I made myself as this is what I will be using the tracer for mostly, keeping track of how well my tubes hold up over time. Feel free to use the footage on your web page if you like to do so.

Kind regards


4th of Januari 2016, Yoshikazu Tanabe from Japan created a beautiful wooden box for his uTracer. Click here to visit his website.

Marie and Ronald

It has been one year since I purchased V3.
I have just assembled it with V3p updates.
I attached some view of my uTracer. I will prepare pin selector(assigner) controlled with MPU near future.

The uTracer is very nice tool for me.
I tried to measure some tubes I have.
It shows the characteristic of tube visually. It is easier to judge good or not.
I am looking forward to see Version 4.

JA3WZT/Yoshikazu Tanabe (Japan)

26th of December 2015, Sebi Carjan sent me a few pictures of his very nice version of the uTracer.

Hi Ronald,

I am glad to send you my uTracer photos!


17th of December 2015, Michael Fleming’s uTracer: indicator light, rotary switches and tubes, a boys dream, fantastic!


I have been meaning to send you a couple of photos of my finished build for some time now. Construction and testing was problem free thanks to your comprehensive instructions. The case ended up being a little more complicated than planned as the rotary switches should have had more positions; but it does work. The uTracer is under utilized just checking valves in friends audio amplifiers.

Thank you for all your ongoing effort in the project and for the high quality kit.

Michael Fleming

Sydney, Australia.

5th of December 2015, Another beautiful uTracer has come to life, this time in the Czech Republic!

Hi Marie-José and Ronald

So I finally finished the final version of uTracer V3. I was a little inspired by the meter from October 22, 2014, Thomas Kiechle. It was the easiest way where to place it, but space was very limited. I have added the source 20V / 2A for measuring tubes with low-voltage glow. Due to the excellent design and processing of uTracer there were no problems and everything worked on the first attempt. For that, many thanks to Ronald and his willingness to share the result of the work with the general public.

I attach pictures and draft of panel.

Greeting from Pilsen, Czech Republic send Vladimir Julius (OK1VJ)

Best Regards Vladimír

29th of November 2015, Florian from Bavaria made a beautiful wooden box around his uTracer!

Hi Ronald and Marie-José,

my µTracer is finished now. it was great fun, following your great manual and kit, the PCB was finished at the 3rd Evening. Planing, sourcing and building the Housing took a lot more time. I added:
- a separate Supply with some 42-43V, with a Step-down to generate higher filament Voltages.
- the Voltages from the HV-caps to the Panel,
- a Potentiometer (0.2-2.2 MOhm) from Anode to one Connector with the Puswheel-Switches i select the source per Socket-Pin, so i prevent shortcuts on µtracer-Outputs. I'm still not sure whether the switches will durable withstand the 400V, till now it's ok.

On photo, i tested a EFM11 magic-eye, a PL504 with tracer and quicktest. next, a GR22-214 (like GR150) Voltage Regulator, with series Resistor 100k. here, for testing regulators (and Zener-Diodes) would it be possible to get hands on the Voltage-A/D while Measurement? So it would be possible to "see" the regulated voltage (between series Resistor and Anode). I already added one Connector for this, adding a separate 470k to the Voltage-Divider R18/R19. (in "debug"-window, a applied Voltage is visible, but Software blocks measurement) the GUI works fine, running on a IBM T60 with xubuntu Linux, using Wine. Using the Dock, i have hardware RS232, also tested a old "HAMA" USB cable with some Philips chipset.

Best regards from eastern Bavaria

25th of November 2015, Joe Carpenter from A to Z Guitar and Ampworks LLC will use his uTracer in his shop!


Greetings from Maricopa, Arizona I'm finally getting more comfortable with using the uTracer and have been busy putting it to good use. I had a couple minor issues one with the 330uH inductor inline with the power supply not allowing the tracer to power up. I have a power suppressor plugged into my Dell power supply It's working good now and I look forward to using it in my shop as an valued piece of troubleshooting equipment. I tell everyone about your tracer and how much I like it, Thank you for all your hard work designing it.

Best Regards and Happy Holidays,

Joe Carpenter
A to Z Guitar and Ampworks LLC.

22nd of November 2015, Shi Haizhou from Beijing, remains very enthusiastic about his uTracer!

Hi Ronald:

Assembled uTracer into a small box. It looks beautiful. I tested some of my tubes. It's amazing when the actual curve displayed in screen, especially the Ultra Line curve.

Can't wait to share my joy with you. Really appreciate. Here are some pictures of my Tracer and actual curve I tested

12th of November 2015, Paul Wilton reports another uTracer alive!


I thought that you might be interesting in seeing another completed µTester3+.

The case was a second hand box which was thrown out from where i work. It’s size means that I have been able to mount the laptop PSU in the bottom to create a self-contained unit. Building the kit was a pleasure. Your instructions are very good - one of the best I have seen. The attention to detail was good and having the stages with testing once completed removes the risk. The only addition I would suggest would be to have a inventory/BOM.


1st of November 2015, Shi Haizhou from Beijing, China reported his uTracer working!

Hi Ronald:

Now, I have assembled all stuffs. It works very well. Here is the working picture and the first curve of one of my 6p30b-q. Compared with standard curve in manual, looks a little bit different. I have the similar result when I tested this tube with my own made tester. Now, with this fantastic uTracer, I can optimize the circuit base on actual curve while not follow the manual blindly.

Thanks again.

15th of October 2015, Marcello Borini reported his uTracer working with the GUI running in Oracle’s Virtualbox under openSUSE, read more here

Hi Ronald and Marie-José

I was busy last month and building my uTracer took a long time. Anyway I finished! ...and seems that all is working fine. Attached you can find a photo of the first prototype.

I used the uTracer "as is". I only changed the two LED using a big red one between the sockets as HT warning indicator and another standard 5mm as Power indicator. I've already tested and calibrated the board following the construction manual and all was ok. The first impression is that uTracer is a very nice device!

I'm also would like to add some of the first experiences using your GUI with my uncommon PC environment: I'm using an old Lenovo laptop (T60) and a desktop PC both running Open Suse Linux 64bit 13.2. Instead of using Wine to emulate windows API, I decided to try to run Windows XP and Windows 7 into Oracle Virtualbox since I would like to use MS Office to edit GUI output reports.

At the end of the test i can say that the GUI works well under Oracle Virtualbox 5.0.X but also under 4.3.X. Attached, you can also find a .doc file explaining what I did to configure OpenSuse Linux and Oracle virtualbox. Feel free to use or distribute if you think it is useful.

I'm going to start testing uTracer in depht.. I'll keep you informed.

All the best

15th of October 2015, Andres Tarik gave an update of the state of his uTracer in an “outdoor ambiance”

"The enclosure is finally finished for my uTracer! Actually, already a couple of months ago, but I am just too lazy to post pictures :) . Front panel layout is based on Martin Manning's excellent compact design. It has seen quite a bit of action since then and has proven to be a really useful tool for what I do for living currently. Here is a small picture of it having a small break from the daily routines, resting in the wilderness :)"

9th of Oktober 2015, Vladimir Julius (OK1VJ) reported his uTracer working!

Hi Marie-Jose and Ronald,

I finished building UTracer3 +. According to the manual was a joy to work with. No problem. Ronald brilliant work. Everything works as it should. Now, waiting for me the hardest. Finish uTracer into its final form.

A big thank you from Pilsen sends Vladimir.
Several pictures in the Annex

Vladimir Julius
OK1VJ my amateur radio mark.

30th of September 2015, Zsolt Botos’s uTracer has a double row of rotary switched in a small case, a wiring nightmare, but ... beautiful!

Hi Ronald,

First and foremost... when I had been started to search for a simple tube tester for more than one year I didn't think I would find such a fantastic measuring device like uTracer.

My love affair with tubes and everything which contains tubes started about 38 years ago when my great-grandma gave me an old Orion 115A tube radio. It was unserviceable, but I plugged away at that while it finally sounded. Tubes are my old love.

I started to construct the PCB from April 2015 in my spare time only. The package, the PCB and construction manual were very fine. During the construction of PCB there was only one problem, but thanks to Ronald's helpful support finally that solved quickly with success. (A faulty BAT86 played a joke on me.)

The uTracer was built into a standard and common chassis. I decided to use rotary switches to solve the connection from uTracer terminals to socket's pins. I used 1x12 rotary switches in 2 lines. In this way every terminal has 2 rotary switches so the multiple connection is simply available. Every type of tube have a numeric code so the testing of tubes is very easy at any time in the future. Of course I wrote the codes into Excel files for later on usage.

Unfortunately I was lazy to construct a PCB for rotaries, but I rued that very much. Soldering of 12x13 pin of rotary switches in so small space needed more time, than time was needed for the construction of complete PCB and resulted a wire tree.

There are also 2 selector switches. One of them is used to select between internal/external heating. (Green banana plugs.) using that and the relevant rotary I can solve every internal and external heating configuration.

Another of them is used to select between normal or continuous mode of anode and screen terminals. Switching it the anode and screen terminals or reservoir capacitors can be connected to anode and screen rotaries and from there toward to socket's pin.

There are a red anode cap banana plug and the tube sockets on the top of the box. The titles are temporary. I have already started to plan the nicer titles.

Finally I would like to thank for the development and I really appreciated for the support I had during the construction. I have to highlight the construction and user manual. Both are simply excellent.

Best Regards,

22nd of September 2015, Simon Wegler sent me an extensive testimonial and some pictures of his very compact uTracer!

Hi Ronald,
hi Marie-José,

it's been a while since I ordered the µTracer and finally I found the time to take some pictures of my version of this fine kit.
After receiving the kit I built it within a week time and it worked flawlessly from the beginning. A truly well engineered and superbly documented device that was very easy to build, even for a "non-IC-guy" like me. I loved it. :-)
After I had finished populating the pcb I had a look on the great builds from all over the world that you show on your homepage. Especially Joe's TTT-3 caught my eye and I decided to try something similar.
Please the the attached files for an impression of my attempt.
I made two small modifications: First I added an "adapter"-board to the socket which was originally intended for the MAX232. Therefore I am now able to directly add an USB-TTL-converter and a TTL-Bluetooth-converter to the board without the need of level shifting. So now I have the choice which interface I want to use.
Second modification is an additional heater-board, which unfortunately is not yet in use, I am still struggling to convert the "squareroot"-PWM to a linear voltage to program a LM2576HVT. Would it be possible to have a non square rooted PWM output? Maybe in a next release of the firmware? For the time being I use external heating.
The finished enclosure holds space for the programming cables (standard 2 mm lab connector), the power supply (not shown here, just a standard notebook PSU) and even a small multimeter (Benning MM P3 with modified cables with 2 mm connectors, also not shown).
Thanks again for this great kit, it is a lot of fun and very useful.

Best regards from Bavaria

8th of September 2015, Brian Munson’s uTracer is in one word “stunning” !

Hi Ronald,

Old School Meets New School-The TV539 uTracer

Thank you for the support during the construction and test of my uTracer vacuum tube curve tracer. I have always dreamed of owning a TV2 and a Hickok 539 tube tester but could never afford or justify the cost. With the uTracer, I was able to build my dream machine with added functionality at a fraction of the cost.

My goal for this instrument was the following:

  1. The uTracer would be the “heart” of this instrument
  2. Have a curve tracer that could test most tubes
  3. Incorporate a test for my vintage radio magic eye tubes
  4. Provide all the metering included on the TV2 tube tester
  5. Package the tester for portability
  6. Provide an additional heater circuit (0 to +50 VDC)
  7. Provide a variety of sockets to handle most tubes
  8. Easily setup when testing tubes
The uTracer was the best kit I ever built. The verification tests during the building stages insured the curve tracer would operate correctly when finished.

Before I designed the physical interface and front panel for the uTracer, I went out on an extensive eBay search for the best Simpson NOS meters that met the uTracer operational and test voltages. Once I acquired the meters, I used the “Front Panel Express” software to design the front panel. The outside dimensions of the panel was based on the Pelican 1500 case. All uTracer components, including the heater “Variac”, were sized with the case depth in mind.

Following your uTracer manual and construction tips, I built the external interfaces to the uTracer and the complete project worked perfect the first time. I have tested over 25 different types of tubes ranging from a missile 6021 subminiature pencil tube to a 6U5 magic eye tube.

Thanks again for all the help you have provided me in my dream project!

Brian Munson

Virginia, USA

6th of September 2015, Ilkka Juurikko from Finland introduces the “lunch-box” uTracer!

This lunch box packed precise tester is very handy to take everywhere and it's an amusing multimedia center as well.


20th of August 2015, Matt Beardsworth’s uTracer is, as he put it himself, straightforward, but nevertheless very useful!

My uTracer implementation is very straightforward. After building the kit and initial testing I mounted the PCB in a rugged carry case from Seahorse. I used E-Machine shop to design a custom panel that screws into the lower lip of the case. An IEC plug and switch connects to a mains fuse, pilot light, and laptop power supply. Since I mainly test audio tubes, only a couple of sockets were needed. These are all wired to banana jacks 1-9. The plate, screen, cathode, grid and heater connection from the uTracer were also made available by banana jacks. The uTracer jacks were duplicated twice up which allows for testing twin triodes tubes in parallel or each half simultaneously. I couldn't be more happy with the uTracer and its ease of use! I have found many bad tubes that have passed other mutual conductance testers with flying colors. Actually having plots for the full operating range has been much more valuable for testing and matching tubes. In Hi-Fi circuits I have had great success lowering THD by matching tubes with the uTracer for critical phase inverter, or driver stages in push pull amps.

About 4 months ago I to the 3+ version without any hiccups. After a recalibration, I was off and running now able to test larger power tubes closer to thier maximum specifications than nearly any other tester! I still have big plans for the uTracer inducing adding a grid emissions test circuits, shorts testing, external AC filament transformer for higher current filaments, and potentally a noise test with a headphone output!

I would really like to thank Ronald and Marie-Jose for this wonderful device. I am still amazed by the quality of the documentation, the software and the kit as a whole.

Best Regards,

17th of August 2015, Winfried Hirsch made a beautiful case for his uTracer using 3D printing, a first!

Hi Ronald,

Finally the uTracer made its way into a ready to use device…

Looking at the date of my last email and the statement „I think the kit is built quite quick“ I have to smile. I really thought I will do that on a weekend, probably one could do, but not me. :-)

I had much pressure in my all day life and business, I think I started the uTracer in February only. At the beginning I was quite unhappy because of everything was so ‚small stepped and combined with so much testing and calibration (did not read that thing about patience you mention somewhere). And of course I mixed up some parts (I hate transistors, that happens always to me with that little beasts) and probably killed the power Mosfet next to them too that way.

But this was good! I already recognized before, that this kit is so well constructed and thought over that it helps to prevent errors and even if they happen one can solve problems easily. As this happened it helped me to find the patience (had to order some parts :-) and just making the steps as small as I could. The uTracer is completed now (since this weekend) and everything works like a charm.

I had three goals for building „my" tube tester:
- Portable operation with a laptop or minicomputer, LiPo battery driven supply (easy to accomplish since the uTracer generates all the needed voltages)
- 3D printed case for my version of uTracer which is just printed without the need for drilling holes.
- Another thing was that I do much with submini tubes and it took long for me to find a way to build a practical setup to measure this beasts.

All is solved and I am happy now that all works as intended. Actually I wanted to gave your work some additional credits with the casing, but that color turned out to be a bit problematic (I hope the pics stay embedded in your mail reader):

13th of August 2015, Joakim has a very nice implementation of his uTracer with some “programmable” sockets and some “hardwired” sockets for common tubes.

Hi Ronald,

Just wanted to write you a short note to show my appreciation for the uTracer.

Got my bag of components a couple of months ago and have now finished my version of the uTracer 3+. Build went sweet, great buildguide including the tips and tricks.

I have built tube-amplifiers for guitar and hifi for a number of years, and now I can really investigate the inner secrets of the tubes to match and sort out individuals with requested characteristics.

I have attached a couple of pictures showing my take on the uTracer implementation, I'm currently running the SW on a laptop running Ubuntu Linux.

Once again thumbs up for a solid and well-working kit.


24th of July 2015, Ken Klein is very pleased with his uTracer!

Hi Ronald;

I’ve had a love affair with vacuum tubes since the nineteen fifties when I began building ham radio transmitters and receivers. I’m still at it today, and have a plethora of old boat anchor radios and amplifiers.

I never had a tube checker and so was forced to determine valve characteristics directly from operation in a circuit. I’ve searched Ebay for a reasonable tube checker, and found that good ones were fiendishly expensive and moderately-priced ones weren’t worth having.

So I scouted around for a transconductance tube checker circuit that I could build that would give me mu and gm and allow me to vary the voltages on the pins. I found something called the RAT Tube Tester which I thought would do the job. I designed a PWB using ExpressPCB and built the circuit and designed and punched a suitable chassis. I never even powered it up!

Having lunch with my close friend Roy, he asked me if I had heard of the uTracer by Ronald Dekker. I hadn’t. He told me that it was not only a transconductance tester, but was a curve tracer to boot! He said that Morgan Jones (one of our heroes) had reviewed it very favorably.

I immediately researched the uTester on Ronalds site, and was rather blown away with the circuit and software. I immediately ordered the kit; and threw the tester that I had just worked on for three weeks into the junk pile!

I built it simply; with a large enough chassis to allow future expansion, such as an auxiliary filament supply and meter and more sockets. The only change to Ronalds board was moving the LEDs to the chassis.

The instruction manual is a triumph of clarity and his method of testing each section as it is built is genius. I had no doubt it would work perfectly when I finished the board and, of course, it did.

Dozens of reviewers on these pages have lauded much of the operation of the unit, so I won’t repeat their praises, but there is one feature that I think needs to be especially highlighted. This is the distortion analyzer. Tube amp aficionados love to play around with boosting n-order harmonics to achieve their desired sound, and nothing is easier with this analyzer. Play with it on the fly as you design because Ronald has already done all the hard work for you!

One other feature that means a lot to me is the pulsed testing that minimizes stress on the tube, even when surpassing the published maximums. I’ve tested many antique tubes, some ninety years old, and knowing that I am not going to destroy “mystery” tubes in running the curves is a real blessing.

It is astonishing how useful this unit is. The very first thing I do when refurbishing an old radio or amplifier is immediately test all the tubes. It's rather fun to do that.

Lastly, I have to add that I stupidly allowed some banana plugs to short when testing a couple of 6AV5s. The damage was fairly serious, since it took out the 19-volt power supply, diode D19; and the high-voltage Darlington pair. All my fault, of course. For some weird reason, the power-on LED began blinking about once per second, so I pinged Ronald to see if he had run into this problem before. He was a great help in getting me through the troubleshooting and repair. It’s now up and running and upgraded to 400 volts. Thank you Ronald!!!

A wonderful machine and I am more than delighted with it.

21st of July 2015, Luis Fernando’s uTracer – the second in Brasil – is an example of a straightforward and efficient construction!

Hello Ronald / Marie José

Please see attached some pictures of the uTracer finished. The second in operation in Brazil...

I´d like to say that your project is fantastic! very well designed, simple to build and operate, also the best assemble instructions I have ever seen...

My simple assemble prioritize small double triodes test and the screws over the top can be used to put a 6C33 socket or an aluminium board with any kind of socket.

As a improvement suggestion, more current capacity would be great to test high current tubes such as 6C33, in my case I´m going to test at 140VCC -50V grid 200mA only a single point using the quick test.

Best Regards


13th of July 2015, Zoltan Benko’s uTracer is a statement of pure craftsmanship!

Dear Ronald,

Sorry for the late reply, took me a long time but I finally finished my enclosure. (In the meantime, I built a mini CNC machine, and I learned how to make anodized aluminum...) Now the instrument consists of two parts: the uTracer box and the switch box, so I can expand it if necessary. I found, this is a fantastic tool! It does everything what I need to test my tubes. I integrated an isolated serial-USB converter in it, so it can be used very safely. Thank you for the great instrument, and for the detailed description.

Best regards,
Zoltan Benko from Hungary

5th of July 2015, Allan Wyatt Curator of the National Valve Museum wrote a nice review over the uTracer

I received your email about testimonials yesterday and this prompted me to write today. Please free free to use any of my images if you feel that they add to your list of successful users. I have recommended the uTracer to many in the valve community and my mk IV Avo valve tester is being reconditioned for me and when it is back we plan to conduct side by side comparisons with the uTracer. The results will then appear on the museum site.

The tester is a joy to use and the only niggle I have is that periodically it will lock-up and I have to reboot.

Click here, to read the article, or become a Friend to visit the complete museum (ed. Ronald)

5th of July 2015, The beautiful small uTracer of Keith Jones made me quite jealous!

Hi Ronald & Marie-José

My apologies for not sending this sooner, but I have been busy with work and your email prompted me to write.

First of all I must thank you again for sorting out my build errors ……The Utracer 3+ is a great design and has formed the basis of a new business opportunity for me, providing valve & amplifier health checks for Guitarists.

It is true that many guitarists are forever chasing the elusive “perfect” output tone and are always stressing that their current valve set up must be the problem. However “Valve & Amplifier Health Checks” may not be the greatest business model for success, as now I can show them the evidence that their valve setup is OK, it inevitably leads them to the concussion that it is their playing ability that needs fixing !!

You can see from the attached photos I have built your tracer PCB into a portable case and opted for just the three valve bases that are common for guitar valve amplifiers, a rotary switch system sets up the valve pin-outs and an old Dell Net Book as the driver when away from my desk top PC.

For testing and tracing a double triode, a 12AX7 for example, I have constructed a simple adaptor that plugs into the unused socket to provide the necessary cross over connections. I have also installed a set of 4mm output sockets so that I can connect various valves on the fly if needed.

Finally a reference chart giving me the pin-outs and typical values for the most common valves that I will encounter, it also fills the blank space on the top panel above your PCB.

Having been involved in my own product design for many years, I know just how much effort goes into a project as complex as this and wanted to say that your hard work and expertise is very much appreciated.

Click here, to download the layout of Keith’s front panel.

4th of July 2015, Teemu Maijala from Finland reports his uTracer working!

Hello from Finland,

I built the uTracer and it seems to work fine. I haven’t yet compared the results with manual tube measurements, but I’ll do that in the future. At least the 1ms voltage pulses from uTracer I measured with oscilloscope seem to match with the values seen in the software. I have had some crashing problems with the software, but it is probably because I have a Mac and I’m using the Windows 7 under Parallels virtual machine.

I have one suggestion to the next version of uTracer: The power- and hv-leds should not be soldered directly to the PCB, but there should be a connector on the PCB so you could more easily attach the LEDs to casing.

4th of July 2015, I am happy to learn that Erwin Schumann from South Africa is using his uTracer extensively!

Thanks for the reminder, I did say I would send you a note but got so busy using the uTracer and designing tube amplifiers I forgot!

Attached are 2 photos of my implementation. I used a 1U 19” rack simply because I had one from an old project and I could fit it into my equipment trolley!

About the build: The assembly and test went like clockwork, thanks to the detailed assembly manual supplied. All components were supplied as specified! I even had a few components spare!

I have been using the tester extensively to characterise tubes for use in LTSpice, and to do tube matching.

I am using an iMac with a USB-RS232 converter, and I am running Sun’s VirtualBox with Windows 7 Home Premium for both Ronald’s uTracer GUI as well as “The Other Graphical User Interface” from

I have compared the uTracer results to an AMPLITEX tester for a few tubes and have found almost an exact match for the small signal parameters Ra, Gm. Visually the large signal characteristic curves also appear to match very well, but I have not done a detailed comparison.

The implementation includes a separate dc filament supply for up to 13V.

Enjoy your summer!

Best regards

Erwin Schumann
Cape Town
South Africa

4th of July 2015, Martin Manning sent me an update on his uTracer

Hi Ronald,

You have a great collection of uTracer start-ups on the Testimonials page. For something different, here is a photo of my workhorse uTracer, which has been in use for almost two years now. It has seen upgrades to the "3+" configuration and others as recommended to improve its performance, as well as the welcome updates to the GUI software. In addition, I have made a few simple but very useful modifications to the front panel since the initial build, which are shown in the attached schematic snippet.

The first addition was a "Continuous Mode" switch (next to the blue and orange anode and screen terminals), which connects the high-voltage reservoirs directly to the panel terminals. In addition to enabling continuous current tests, this switch permits a check of the boost converter voltage calibrations without having to open the enclosure. A prepared test set-up, stored as a .uts file, makes this very easy.

Next, provision for connecting an external heater supply was made with a switch and another pair of jacks so that high-current audio power tubes and rectifiers can be traced. The switch is located next to the brown internal heater supply jacks, and the second pair of brown jacks with the red and black leads is connected to a bench supply.

Most recently, another switch was added to the front panel just below the continuous-mode switch. This is a dedicated calibration switch, which connects a pair of 10k, 1% resistors from the anode and screen terminals to the cathode terminal. With this switch engaged, a quick check of the current amplifier calibrations can be made, again using a prepared calibration test set-up. This calibration switch integrates nicely with the "continuous mode" switch just above it, and the switch connections are arranged such that the 10k current amplifier calibration resistors cannot be connected when continuous mode is selected.

This is not to say that the uTracer requires frequent calibration, and in fact I have found it to be very consistent in its operation. It is reassuring to be absolutely certain that everything is working properly before a session of tracing, though.

Best regards,

Martin Manning

4th of July 2015, Simonson Lasse shared a few pictures of the matching of an impressive FU-29 tetrode.

Just want to share some pictures of the tracer.

Here a FU-29 tetrode which is the output tube in an audio amp I have. There is clearly a difference between section 1 and 2 in this one, about 15mA. The settings is about the same as in the amplifier. Screen 220V Plate 420V and grid -20V.

It sure is a fun little (but powerful) tracer/tube tester.

1st of June 2015, Bodo Fuhrmann reports his uTracer working.

Hi Marie-José and Ronald,

Last week I finally started assembling the kit -- without any problems.
It took only some hours, one afternoon. The manual was very detailed, especially the point by point steps with hints...
One feels, "the kit was made with love".
I attach some images of first tests without a case (as I know myself, I never will construct one)
I use a more than 10 years old laptop with XP and serial interface an some breadbords with tube sockets from a former tube tester project.

Pictures: EF14 comparison of two tubes, ECL11 triode section comparison of two tubes

Thank you very much again and best regards


3rd of May 2015, Norm Campbell reports his uTracer working and he has a useful tip regarding the USB-2-Serial converter.

It works! See attached picture of it measuring an old 12AT7.

The instructions were excellent and the kit went together with no problems. What did give me quite a bit of grief though, was the USB-RS232 converter. In case my experiences can help any future uTracer users:

I used an adapter cable based on the PL2303 (on Windows XP). But every time I would power up the uTracer and start the GUI the communication would hang at the first command, and then not only could the GUI not be shut down, but I couldn't even do a clean shutdown of my PC - I had to kill the power. Eventually I realized that at powerup, the uTracer sends some noise or glitches on the COM port and whatever it is seems to hang the PL2303 driver. So now I power up the uTracer and THEN plug in the RS-232 cable, and since then it's been completely reliable.

I look forward to using the uTracer a lot in aid of developing software models of tube amplifiers. Should be interesting.

Oh one question - R17 and R31 are unpopulated - I assume this is intentional? I didn't see any mention of them in the instructions, although other unpopulated components are called out.


30th of April 2015, Alexandre Torchelsen Feldens has brought the first uTracer to Brazil!

Prezados Ronald Dekker e Marie-José,

Eu concluí a montagem do gabinete do meu µTracer. Eu usei um gabinete de uma fonte de alimentação PoE da Cisco (para Access Point de grande porte, de exteriores), cujo circuito estava muito danificado. O tamanho não poderia ser mais convidativo: a largura é a mesma da placa do µTracer, e o comprimento deixa apenas uma sobra para colocar uma placa onde irão os conectores RJ-45, a fim de aproveitar a furação original da caixa. Um RJ-45 serve para o serial (onde eu usei o mesmo padrão que a CIsco usa em conexões serias via RJ-45, e o outro soquete foi para a alimentação, com alguns pinos em paralelo, a fim de suportar a demanda de corrente do µTracer. Os LEDs originais da fonte foram utilizados também. Existem muitos furos de ventilação (bom para o circuito), e os mesmos permitem inserir parafusos M3, que eu utilizei para formar uma torre de fixação das placas onde vai o soquete da válvula. Eu já criei as placas para válvulas octal (em algumas fotos existe uma 6EM7 no soquete octal) e também para as de 9 pinos miniatura (o próximo será para os 7 pinos miniatura). O fusível de filamento foi montado no centro da torre, externo ao traçador, a fim de tornar a substituição fácil no caso de avaria.
Utilizei largas "miçangas de ferrite" (ferrite beads) a fim de eliminar possíveis oscilações. Tal medida provou-se vitoriosa: nenhuma válvula em boas condições testada oscilou, incluindo três E810F!
Eu ia usar adaptadores montados com conectores DB-25, porém como eu percebi que vou testar muitas válvulas com pinagens diferentes, eu optei por algo mais arriscado: deixei os terminais de teste com garras jacaré, e eu simplesmente os conecto nos pinos corretos, na hora do teste. Isto requer mais atenção a fim de evitar trocas de pinos ou curto-circuito entre as garras ou entre elas e a carcaça. Porém como geralmente eu trabalho desta forma em laboratório "desde sempre", estando acostumado a este processo, está OK assim para mim.
Agora centenas de válvulas estão à minha espera para serem testadas!
Mais uma vez, muito obrigado por produzir um kit bem organizado e com inúmeras opções de funcionalidades!


Dear Ronald Dekker and Marie-José,

I concluded the assembly of my ?Tracer case. I used a case of a Cisco PoE power (for large outdoor Access Points), whose circuit was badly damaged. The size could not be more inviting: the width is the same as ?Tracer board, and the length leaves only a little space to put a PCB where the RJ-45 connectors reside in order to take advantage of the original features of the box. An RJ-45 serves for serial (where I used the same pattern that Cisco uses in serial connections via RJ-45, and the other socket was for supply, with some pins in parallel in order to support the current demand the ?Tracer. The case LEDs have been used as well. There are many ventilation holes (good for the circuit), and they allow me to insert M3 screws, and I used to form an platform tower for PCB where resides the socket of the valve. I have created the PCB for octal valves (in some pictures there is an 6EM7 in octal socket) and I also made the 9-pin miniature (next will be 7 pin miniature). The filament fuse has been mounted in the center of the tower, external to the tracer in order to make easy replacement in case of malfunction.
I used wide ferrite beads in order to eliminate possible oscillations. This measure proved successful: no valve in good condition tested oscillated, including tree E810F!
I would use adapters fitted with DB-25 connectors, but as I realized that I test many valves with different pinouts, I opted for something more risky: let the test leads with alligator clips, and I simply connect the correct pins on moment of the test. This requires more attention to prevent pin exchanges or short circuit between the alligator clips or between them and the housing. But as I usually "always" work this way in the laboratory, I am used to this process, so is OK for me.
Now hundreds of valves are waiting for me to be tested!
Again, thank you for producing a well-organized kit and with numerous choices of features!

Best Regards,

Alexandre Torchelsen Feldens
From Foz do Iguaçu - Paraná - Brasil

4th of April 2015, Bjørn Aaholm reported his uTracer up and running!

Hi Ronald,

Just a quick note to let you know that I managed to assemble my uTracer3+ and have succesfully traced a tube with it.

It was a joy to assemble the kit, well done with the manual and packaging!

Now I have to decide on an enclosure and make a jumper array for connections. I will send more pictures when it's done.

Best regards,
Bjørn Aaholm

1st of April 2015, Leung Hok Man from Hong Kong send a few photo’s of his very complete uTracer

Dear Ronald,

Long time haven’t email to you.
How are you?
I feel very sorry that for the delay of the photo of your product.
This product is very good for me and I using the Cost RMB 40 Bluetooth COM port is very good.
But I using the Pad with resolution 1280 X 768.
I cannot display all the detail for on the program.
Please enjoy the photo and looking forward to your update version.

Leung Hok Man from Hong Kong

24th of March 2015, Andres Tarik’s uTracer in Tallin, Estonia is up and running!


Just wrote to inform you that there is another uTracer up and running, location Tallinn, Estonia :). Everything went smoothly, no problems at all. Which was actually predictable considering the excellent documentation provided with the kit. I can’t even imagine how much time has been spent on it. Once again, excellent and many thanks!!!

Will take some time to figure out a decent enclosure, but it will happen soon enough. Until then a small preview of it testing a random 6v6.

All the best,
Andres Tarik

2nd of March 2015, Roger Bentley’s compact uTracer can serve as an ornament on any drawing room table!

Dear Ronald,

here are a few photos of my uTracer in action. The case is constructed according to a superb Martin Manning design and is a Hammond 1590D so very compact! After a couple of problems that were entirely my own fault, forgetting to limit current and switching off the compliance(!), here you can see the uTracer in action measuring a 12AX7 dual triode. 12A*7s have their own hardwired socket as I test a lot of these. The other tube is a Brimar 6V6GT which tests perfectly.I also have tested a pair of 6V6GTAs supplied to me for a Fender 5E3 build and they match almost exactly! This is an amazing piece of equipment so thanks to Ronald for making it available to us.


1st of March 2015, Rudolf Moers finished his uTracer!

Hello Ronald and Marie-José,

The engineering of my uTracer is ready.

Photo 1 is the rear side of the top plate with the 'spaghetti like' wiring. All wires can handle 400V. On the bracket right below photo 001 a small heater supply circuit is mounted. Most of my tubes need more than 1.5A heater current and sometimes the heater supply is lower than 4V. Therefore I have made a separate adjustable supply circuit of 1.2Vdc thru 12.6Vdc and 0 thru 3Adc. For more heater current I will use a laboratory supply.

Photo 2 is the top side op the top plate with several tube sockets. I have copy/paste the colored banana chassis parts with the colored test leads from the other uTracer builders who came before me. At the top right side of photo 2 you can see two displays, one for the heater voltage Vff and one for the heater current Iff. At the other side of these displays is a small printed circuit board with a voltmeter circuit. It can be supplied by 3Vdc thru 30Vdc and can measure voltages from 0Vdc thru 99.9Vdc. In series of the (+) heater wire I have placed an accurate resistor of 1 ohm/1 %/10W. Another voltmeter device across this resistor gives a measured voltage which is equal to the heater current (e.g. 1.6V = 1.6A x 1 ohm). The cost of one voltmeter device is 2.95 euro and the cost of the accurate resisor is 8 euro.

Photo 3 gives an impression of the complete uTracer box. For 21 euro I cannot make such a wooden box so accurate.

Photo 4 shows the inner side of the wooden box. In the middle is the uTracer board. At the left side is the mains entree and I use 2 labtop supply adapters (with fuses). One for your uTracer board and one as supply for the adjustable heater supply circuit. The blue part is the RS232/USB convertor and at the right side is the USB output connector. The small printed circuit board right below has fuses for the fixed Va and Vs outputs (w.r.t GND). The yellow/green wire at the left side will be connected to the metal tube socket plate for safety earthing. Thanks to the clear construction manual, the engineering of the uTracer board (in the mean while upgraded to the 400V version) itself was very easy.

The educative operation manual makes the measurements easy to carry out. The features of the uTracer are great and I have used them all. It's amazing that you designed and engineered the uTracer circuit in your free-time and made it available for the whole 'electron tube mankind'. And also amazing are the design considerations mentioned on your beautiful uTracer site. And last but not least, many thanks for your personal support and after care whenever customers need.

Best Regards,

Rudolf Moers

The Netherlands

17th of Februari 2015, Rudie Dorrepaal reported his uTracer working!

Hi Ronald,

The overview on your website shows that there are currently 3 operational uTracers in Ireland. Not sure if that number includes my uTracer, but it should because I just traced my first (EL84) valve curves with it. I was looking for something with basic valve trace capability for a long time and was delighted when (by chance) I saw your uTracer demonstration during the NVHR event in Driebergen. Its functionality by far exceeds what I was looking for, so (as you probably remember) I decided instantly to buy the kit. It was a true pleasure to build this uTracer and even though I hadn't assembled/soldered a full PCB in over 35 years everything went very smooth. The superb assembly instructions manual with a test paragraph for each functional section of the board provides the confidence to continue to the next section in the knowledge that everything from the previous section is fully working. The detailed photos included in the manual provide additional information. Furthermore all the parts are in separately labelled bags, which rules out mistakes made by picking the wrong component.

Once I had completed the assembly and calibrated the uTracer, I moved on to the User manual and I found that apart from this extensive manual, there are additionally YouTube videos explaining everything in great detail. It's amazing that you created all this in your spare time.

My grandfather build a radio in late 1927 or early 1928, which I unsuccessfully tried to restore when he gave it to me about 37 years ago. I now will make a second attempt after I have tested these ancient valves (the Philips F215 , C142 , D143 and 373 ) with the uTracer. This should be a fun project as well since this TRF radio includes honeycomb coils and everything is connected with bare 4-sided wire. This radio even includes a variometer for tuning the external antenna.

Thanks again for this uTracer kit. In the coming weeks I will need to study a bit more on what all the additional capabilities of this tracer are. I also intend to build the uTracer neatly into a case, add extra valve sockets etc. It was a joy to get a taste of Electronics again, because after completing my electronics degree in the past I ended up working in the software industry instead.


P.S. The attached photo's also show the solder frame I build and used for this project.

17th of Februari 2015, Semir Nouri uses a plug system to connect different tubes to the uTracer (click here for a schematic of the wiring), after a small incident with two exchanged voltage regulators his uTracer is now running fine!

Hi Ronald,

Just a quick update on the progress of my project. I've built it into a box now and made the interface for the coded plugs. I have also attached a pdf of the Plug wiring and an example how an EL84 plug is wired. Feel free to share this on the µTracer page.

I have chosen to integrate only the most common tube sockets to keep the box small, Since the DB-25 plug Interface has all the µTracer signals and supplies I am planning to make special adapters that have the more bulky exotic sockets on a PCB together with the plug on one side. I am also planning to make a "universal" plug that has individual wires and jacks for each pin and can be re-wired as needed.



Hi Ronald,

The two PGA113 chips came last Wednesday and I put them in immediately as you can see from the attached image. It was a bit fiddly but manageable even without using the microscope station in my office. Thank you very much for sending those replacements. I have also posted my experience with the great support you give for this project in the "RBF" forum to encourage more users to build one.

My µTracer is finished now and I am very pleased with its functionality. I have already measured many EC92, EF41, EF42, EL41, EL84... It is nice to finally be able to measure and compare different tubes.

I started working (playing) with circuits using tubes in the early 1970's at the age of 12 but later my interests moved to transistor technology and integrated circuits. It was just a few years ago that I rediscovered tube technology and I started to repair old radios as a hobby. Today I have a small collection of antique radios the oldest one dating from 1938 and a black and white TV (Imperial 1223) that I have reanimated. In order to keep these running and for experiments I sometimes buy "bulk" collections of tubes from Ebay and so far I have been testing the tubes by putting them in a suitable radio to see if they work. With the µTracer I can now get a much more clear idea about how good a tube still is.

Things left to do for me are to build more DB25 code plugs e.g. for EF80,85,183,184 and an external heater supply for "U" type tubes that require around 30-70 Volts. I am also thinking of building a true RMS add-on with an AD536 to measure the true heating voltage resulting from the PWM drive circuit used in the tracer.

For now, however, I will just enjoy this nice new addition to my measurement tools!

Thank you again for this nice project and your support!

Best regards


15th of Februari 2015, Philip Jones’s very compact uTracer is especially built for the testing of the tubes in his guitar amplifier(s).

Hello Ronald,

Just to let you know that another functioning unit can be added to your UK list. I will be using it to test the valves in some vintage guitar amps that my son and I have, hence only a 8 and 9 pin sockets. I wanted it small and simple, so it was built into a old battery back up case for a server unit. There were no problems with motherboard build ( thanks to your build and test procedures) and the other components fitted in quite nicely. Attached are a few photos for your collection.

Kind regards

Philip Jones

13th of Februari 2015, Luke Robertson’s uTracer: designed in the Netherlands, assembled in Canada!

Hi Ronald and Marie-José,

I just finished converting my uTracer3 to 3+ and thought I would take a minute to thank you for all of your efforts in making this project available. I really enjoyed putting my uTracer together and the conversion to 3+ was very straightforward.

I've attached a few pictures of my build to this message. I liked Robert Hewitt's build, so I also used a Hammond 1550J enclosure. For my purposes, it worked out nicely. I etched the labels into the aluminum using ferric chloride (a technique very popular with diy guitar effect pedal builders). It's not the greatest etch, but it's legible and it's permanent.

Thank you again for sharing your knowledge.

Kind regards,

31st of Januari 2015, After a small hiccup also Philipp Mittelstaedt’s uTracer is up and running!

Hi Marie-José, hi Ronald,

I hope I can pay a little bit back with some pictures and experiences. After the construction, which was very easy (for beginners also) my µTracer worked and I started to build a case. I decided to take a tool- or camera-case, my is water- and air-proof, for the housing (available in Germany at Pollin.) My wife then made an alu-plate for the sockets, pin-connectors and switches. As wiring I used silicon-cables. After a while of work of construction all was finished and I started to test the µTracer. There I made a mistake. With the great support for the µTracer from Ronald we found the component and its parts which failed. After changing them, all went fine again. Now, after little corrections, my µTracer has arrived his warm appartment. :-) Next step will be to include the possibility to measure MAs and to find out how to measure old tubes with possible inner shorts. In short words, Ronald, thank you for the cheap possibility, for newbies also, to test tubes. The µTracer is very useful!

All the best


Follow Philipp’s thread on “Radio-Bastler-Forum”

20th of Januari 2015, Herbert Jeschke’s uTracer has a huge number of sockets and plenty of space for more!

18th of Januari 2015, Tudor the Zoete’s uTracer implementation resulted in a very nice and compact piece of equipment.

Hallo Ronald,

Hier 2 foto's van mijn tracer, heb hem al geruime tijd inbedrijf doch niet gefotografeerd.

Hij werkt prima, is makkelijk ingebruik, heeft veel mogelijkheden en laat dit ook dan fraai zien. En doet niet onder of meet zelfs beter dan de veel duurdere (gecalibreerde) apparaten.

Heb ook wat andere testers doch die zijn ook nog eens erg lomp en zwaar, bv. de Russische L3-3, dus een uitgesproken kans de tracer zo klein mogelijk houden, en dit met minimaal gebruikte materialen. Heb zo gebouwd dat hij de adaptors van een andere tester kan gebruiken.

Te zien is het gebruik van 2 kleine Sunon Maglev ventilatoren met een toerenregelaar tegen de warmte.

Zou je wel exact de spanningen willen meten/afregelen, bv. de gloeispanning, dan is een echte RMS (AC+DC) meter benodigd.



14th of Januari 2015, Francisco Martin Garcia from EDINTEC build his uTracer in the well-known fashion.

Dear Ronald and Marie-Josè:

Greetings from Madrid. I’ve finally decided to show my uTracer mount. First of all, I must send you my congratulations for the design, developing, documentation and for the overall project, a magnificent project.

As you may notice, my uTracer is basically based in the model described in the manual (if something works and is good, why change it?). I didn’t have any major issue in its mounting.

This device it’s being very useful for vintage equipment repair services (Becker auto-radios, Emerson, …). The last device I’ve repaired is a Wandel&Goltermann SPM-1 (selective level meter with magic-eye visor) which had a faulty PL81 valve.

I’m pretty sure that you’ll solve the issues with the development of version 4.

Thank you very much for your wonderful work.

Francisco P. Martín García

13th of Januari 2015, Christoph Krüger from ”Radio-Museum Linsengericht e.V” uses an adapter system to connect different tube sockets to the uTracer.


Here are the first pictures of my µTracer version.
I plant it for max 12pins (Compactron).
All Pins, which might be G1, got an additional Induktor to avoid oscillation. A test with a D3a (35mA/V) was also successful.

Christoph Krüger

9th of January 2015, After a few hiccups, Ian Sefchick’s uTracer came alive without any problems!

A word about my uTracer experience:

I had some trouble when I first started to assemble the uTracer. Thanks to the modular testing method of assembly I was able to email Ronald and get it resolved. I thought the problem was a bad PIC and although skeptical that the PIC was the problem, Ronald sent me out a new PIC free of charge the next day. As it turned out it was not the PIC after all and just a faulty 33pf cap! The rest of the build went very smooth and I'm now testing and matching tubes for my boutique audio equipment.

Its really a great instrument. I've been using the quick test and love it! Its so great to quickly see the gain and percentage of nominal current. Tested some dual triodes (6DJ8) and seeing data for both triodes side by side is just fantastic. took about 4 min. for the tube heaters to fully stabilize. While they heated up I was doing curves in the other window and watching the changes. Having loads of fun!

Thanks again,

31st of December (!) 2014, Joe Leskovar from Canada is the first to a report an uTracer3+ finished! His stunning TTT-3 (Tube Tester & Tracer) - powered by uTracer3+ - is a miracle of compact construction!

Hello Ronald..

Greetings from Canada...
I finally finished my uTracer!!!!... I guess I waited just long enough to implement the 3+ specs..
Although it was a long time coming, since I had the case/ panel made up in March, everything calibrated up and it works with no difficulties...
Info here..
Wishing you and your family a Happy New Year.



19th of December 2014, The wonderful uTracer implementation of Thomas Mayfield is something in between an instrument and a work of art! It must be the ultimate dream of every man who (like me) has within him a boy hood fascination for tumbler switches!

Hi Marie-Jose and Ronald:

Well... 4 months later and I have all but finished my Analyzer. A long and lengthy ‘Honey Do’ List got in the middle of my build.

I must say, what a pleasure it was to put together such a well-engineered kit. I really liked the idea of testing the various circuits during the build. The only changes I made... (For the sake of easy replacement) I installed transistor sockets for the transistors in the high-voltage switches, in the event that I managed to cream some of them. I know Ronald made the circuit short proof, but it’s not Old Man Proof. I also opted for USB and jumped over the MAX232.

The calibration went smoothly and my first test with a 6L6 worked perfectly. Now I am on my way to the Metals Yard for a piece of Perforated Metal for the Bottom cover. When I Add 4 Rubber Feet, I will call it done!

For Selecting the Tube Pins... if I was to use Jumpers, I am sure I would make mistakes (getting Old and Cranky -- sucks), so I opted to use a 6x9 Toggle Switch array for selecting Pins. Cause I already had a box full of them. I would have used the Thumb Switches as some builders have done, just could not find them with the Voltage/Current ratings I wanted. Rotary Switches were closely considered, but were just too $$$. I wired the Array in such a manner as to lock out any possibly of selecting any two outputs to the same Tube Pin.

I added some Addressable LED’s to indicate the chosen connections just as a double check for me. I find that the Ladies like the colorful lights!! :) This complicated the build by having to dedicate a Leonardo Arduino MPU just for the control of the LEDs.

I also added a rotary switch assembly along with a Chinese Voltmeter to test for any Tube Shorts, before powering up the uTracer. I quickly discovered that I need to open all the matrix switches before using the short test or bad things would happen. Kind of a pain.

The chassis is made of an old Monitor Riser and a friend of mine Power Coated it White for me. I decaled it and over coated several coats of a clear lacquer. The wooden enclosure was made from a scrap piece of ‘Ipe’, left over from rebuilding my Deck. One of the hardest woods that I have ever worked. If you look close in the Photos, there’s a few corners broken off during cutting. Snapped off Kinda like glass.

I used two of the 19.4V Wall Warts, one for the External Heater along with a Chinese Buck Converter/Regulator, a Chinese Voltammeter and a ten-turn Potentiometer, for accurate heater control. There are two panel switches for External/Internal heater selection and Filament Reversal.

In the Bottom View, you can see where I used a circuit board to carry the Tube Sockets. The uTracer Board is Piggy Backed on the Socket Board. In addition, Piggy Backed is the Arduino. I used a Boatload of Suppresser Beads on the Socket board as well. Looking closely you can see where I offloaded IC1 onto an oversized Heat Sink that has been bouncing around in my junk box for decades. Finally, hidden under the Power Supply chassis is the Switch Matrix with the 324 Stupid solder connections that I had to make. I have now developed a strange twitch that has yet to go away.

Most tubes that I will be testing are Directly Heated Triodes with 2.5 and 5V Heaters, used in Antique Radios. I am finding that the Internal Heater is very accurate, once I establish the correct Heater Voltage setting for any particular tube.

Thanks Ronald!

Tom Mayfield

21st of November 2014, Ruud Jansen (71) from Holland reports his uTracer working! Click here to his weblog on the project (in Dutch).

16th of November 2014, Pieter Bareman made a nice box for his uTracer and demonstrated it on the “repair-day” of the NVHR.

The “Dutch society for the history of Radio” NVHR unites people who are interested in, or collect vintage radio equipment. It regularly organizes “repair-days” during which collectors share their enthusiasm for vintage equipment by exchanging repair and restauration experiences (photo’s by Piet Blaas).

2nd of November 2014, Peter Block has his uTracer working and he is very pleased with it!

Hello Ronald & Marie-Josè,

Personal reasons have kept me until recently from starting work on the utracer; so I`m happy to let You know that finally I put the kit together! Following Your fantastic construction manual I encountered absolutely no problems. Step by step everything worked out perfectly, and soon I had the first curves on screen!

The level of knowledge and craftmanship on Your beautiful and often funny website is amazing, if for me being an elctronics amateur only, not always easy to follow. Thank You for giving us tube-heads this "state-of the-art" tool!

So what remains to be done for me is to build a practical yet simple housing, and learn what this gadget can really do. Also download the new GUI,try the advanced calibration procedure for -ug 1...

So again: Thank You for Your great project and please keep up the good work!!

Yours, Peter Block

P.S: I added some pics and will do so again,when the µ-tracer is really finished.

2nd of November 2014, the case for Steve Blackmore’s self-repairing uTracer is finished!

Hi Ronald

Utracer arrived - checked out and working fine - mystery how it repaired itself. Checked all the joints on the inspection scope and they all looked good. A better method of testing heater to anode/cathode/screen/grid etc needs thinking about. I wouldn't have broken mine if I had tested on the AVO first, but it was a brand new allegedly tested valve!

I've attached a picture of the unit. It uses two power supplies, one fixed 3A supply at 18.5V and the other a variable 5A supply for the heater.

The switch setup is same as the AVO CT160 I have. They were expensive and came from a surplus supply house in the USA. I prefer the switches - less confusing than jumpers and the AVO data sheets cover much about all the valves I'm ever likely to test. Switch setup as shown is for ECC83 types.

The wiring to the valve sockets is loop style with 3 ferrites per loop and one additional one on each switch output. The A2 on/off redirects the screen connection to A2.

I don't have the Gas test working, not sure how to implement that.

If you need any more information please ask.


Steve Blackmore

1st of November 2014, Klaus Haber reports his uTracer working, and he is a bit surprised it works so well!

Hi Marie-José,
Hi Ronald,

Thanks for the nice kit and the very good building documentation!

I have finished building µtracer3 without any problem!

After calibrating, I immediately test a ECC808 and compare the measure result with an commercial datasheet. Its amazing how well the µtracer3's ECC808 measurment result is matching with the commercial Telefunken datasheet (please see attached files)!

In the next step the µtracer will get a "nice home" (I mean enclosure)! Afterwards I can send you some pictures of the complete building result.

regards from Austria, Klaus

22nd of October 2014, Thomas Kiechle’s uTracer looks very professional!

Hello Ronald and Marie-José,

By now I also have finished to built up my µTracer. The assembly of the PCB and the test and calibration constituted no problems due to your excellent detailed manual. I built in the µTracer PCB together with the tube sockets, the power supply, the USB converter and some plugs in a small portable tool case. I realized the connections to the tube sockets using some 4mm banana plugs. To control the unit I used an old notebook with Windows XP installed.

Until now, I tested about 150 different tubes (mostly used) of the E- and U-series from my stock. The "Quicktest" is very useful for a rough measuring and classification. By doing this I was surprised to have a very small amount of really bad tubes. Also I traced some very old tubes (RE..., A...) and several magic eyes.

During this tests, I compared the measuring results using the built in heater supply and using an external power supply. I asserted a little lower measuring results with the built in heater supply. For now I set a slightly higher, experimently determined, heater voltage to compensate this issue. Is it possible to realize a calibration of the internal heater supply, maybe in a future version of the GUI ?

Altogether, the µTracer is a very useful and performant tool for my hobby ! Thank you !

Best regards


19th of October 2014, Michael Drexler’s uTracer in New York is up and running, and it looks great!

Dear Ronald (and family),

Many greetings from New York, where another uTracer has just sprung to life (just about time since over a year has passed since you sent the kit over). Like so many others, I cannot compliment you enough on how well documented the kit is, and how easy the build was (took a good day, and that was not rushing it). In the building stage, I opted for a standard 5.5mm DC plug with positive tip that stayed connected throughout the soldering/testing to avoid "polarity fireworks"... easy enough. One thought for the next PCB iteration would be, if at all possible, to eke out a bit of space for the HV LED so a small non-reversible PCB connector can be fitted more elegantly than what I had to do... it's literally a question of 1-2mm :)

As I have a fair few 2A3s to test, I opted for an external power supply in addition to the built-in one -- based on LM2576 with a resistor array, so I can do "life tests" with 10% reduced filament voltage and tame inrush current by starting at 50% filament voltage. Took a leaf out of your book and am driving the LM2576 with another small laptop supply, just can't beat those for size!

The hardware and socket wiring was, as always, the most trying part, particularly as my humble apartment does not have space for a workbench (and the Manhattanites have no idea what DIY is, so none of this can be outsourced to local shops either).

Chassis is a Hammond 12x8x2, which is a bit tight, but does the job if one is careful with placing things between the large PCB caps, making everything very portable. Left hand side is free-wired sockets with the trusty 2mm banana plug method, right hand side is pre-wired for the valves I most commonly use (with a rotary for three noval types that are close enough to be handled with 4 poles). P/S selector and DHT switch make sure that a) Heater+Cathode are connected for DHT testing and b) uTracer cathode lead is isolated when using the internal P/S on a DHT. Main calibration voltages (Vsup, C13, C18) are fed to 2mm jacks in the back panel, so I don't have to look inside again for quite a while!

Final shot shows everything in action when testing a 5691... works a treat! What can I say, for $350 all-in this beats handsomely both the Amplitrex route at >7x the price and the roulette with antique testers. I use a Sencore TC-162 (they cost $150-200 for us US dwellers, and can easily be refurbished to new by anyone who can hold a soldering iron for $40 in parts) to weed out shorted/gassy tubes before introducing them to the uTracer... valve testing sorted for life! The GUI is also incredibly easy and intuitive, both the curve tracing part and the super convenient quick test.

Thanks again -- you have built something truly wonderful for the international valve enthusiast community! All my best,


6th of October 2014, Helmut Löwenau’s uTracer is beautifully compact!

Hi Ronald,

I nearly finished my uTracer3. Still missing is a rimlock base, and I do some experiments In labeling the box. While testing many of my older tubes , I found out that there is lots of spare place in my laboratory!!! Thank you for constructing that excellent tool .The manual included in the kit is the best i have ever seen and worked with.

Best regards,

29th of September 2014, Eric Bourgeois added a beautiful uTracer to his already impressive laboratory!

Bonsoir Ronald,
Vous trouverez en pièce jointe quelques photos de ma réalisation. L’appareil fonctionne parfaitement.
Je teste actuellement la version GUI 3.11.6 et en particulier la mesure de distorsion qui est très prometteuse!
Je travaille actuellement à l’amélioration de la linéarité de l’étage d’entrée d’un ancien récepteur de radioamateur à tube.

Ronald Good evening, attached are some photos of my achievement.
The device works perfectly.
I currently testing the Version 3.11.6 GUI and especially the distortion measure is very promising!
I am currently working on improving the input stage linearity old ham radio receiver tube.

23rd of September 2014, Kurt Schmid wrote an extensive review of the new QuickTest Features for the “Radiomuseum” forum (in German).

1st of September 2014, Morgan Jones wrote a very favorable review of the uTracer in Linear Audio. For the full article you have to buy the book.

30th of August 2014, Brian Fisher is ready for the winter!

Hello Ronald,

I hope this email finds you well. I have enclosed a couple of photos of my completed uTracer. Your kit was a joy to build and worked correctly the first time it was powered on thanks to you modular testing methodology. Like a few others have done, I chose a Pelican brand case to house the uTracer. The front panel is from Front Panel Express. I also included functionality to perform low voltage sweeps as mentioned in your documentation.

The first photo shows a 6L6 under test. The GUI is running on a virtual instance of Windows 7 with a Linux host. The curves match nicely with published documentation. The rather large device hanging off the RS232 port is a RS232 isolated interface as I discovered during testing of the heater supply that my oscilloscope (which is connected to the same computer) and the uTracer share the same ground. I was a bit startled when I found I could light the bulb by connecting my scope across the bulb.

Thanks for making this kit available. It made for a fun Summer project and now I can look forward to spending the upcoming Winter testing and evaluating my collection of vacuum tubes.

Best regards,


21th of August 2014, Roger Pion’s uTracer is working after a difficult start with a broken BAT86 diode.

The uTracer appears to work properly. Here’s the first test with an el84.

5th of August 2014, Gerald Janisch reported his uTracer working and wrote a very enthusiastic review!

Hello Ronald and Marie-José,

a few days ago I completed the building of the uTracer. It is a pleasure to build it because all parts are clearly arranged in labelled bags so it is easy to find everything, and the construction manual is very straightforward so it is always clear what to do next, thank you very much for this, a really great work! The uTracer came alive without any problems.

The first test I made was with with the 10k resistors on anode and screen connections for calibration. Then I prepared a noval tube socket with wires to connect it to the uTracer and checked some EL84 tubes I had laying about to get familiar with the operation of the uTracer_v3p10 software which is a really great program. It came to communication with the uTracer board without any problems as the PC where I installed it has a standard COM port. I as well tried it on Linux with wine, and it also was working with the uTracer board without any problems.

It is very interesting to see how different measure results several EL84 tubes give, especially used ones, but also new unused exemplars are not very equal. So the uTracer is extremely useful for matching tubes and to see in general the condition of a tube.

Only one problem I found, but I am not sure if it really is a problem, maybe I am overcautious: I was a little bit worried about the temperature of IC1 (maybe without any reason), although it is equipped with a cooling device. So I added for additional cooling temporary a band of copper sheet to IC1 (will change this when I put the uTracer into a case), and now the temperature of IC1 is considerably lower (and I feel better with that).

I include some pictures of the uTracer (also in 3D versions if you maybe have a 3D monitor or TV) and some screenshots and plots from the uTracer_v3p10 software operating at my first tests. At the time I am looking for a case. I want to make a similar arrangement like yours with the mini banana plugs as you suggest it in the construction manual.

When I have integrated the uTracer into a case I will give you an update.

Thank you and kind regards
Gerald Janisch

4th of August 2014, Carlos Saavedra made an elegant two box case (be careful for oscillations with long wires!).

Hello, Ronald:

Attached are a few photos and the schematic of my sockets box. Using a Taylor 45A tube tester to power the 45v filament of a UL41 tube. Next, i'll modify the Taylor 45A for use its sockets and pin switches with uTracer. Will send photos as soon as finished.

Best regards,

Carlos Saavedra

4th of August 2014, Mano reported his uTracer finished with a very enthousiastic testimonial (I wouldn’t have sold my AVO tester!).

Hi Ronald and Marie-José.

I enquired and received the kit from yourselves in Feb of this year. The kit and the assembly instructions were absolutely spot on and the tests at each stage of build only encourages the progress. It took me about a weekend to assemble the uTracer3.

I was using it without an enclosure to test out 6L6GC valves in a push-pull audio amp. Prior to the uTracer3. I utilised an AVO-MK2 which was good, however with the uTracer3, I was able to check and verify how matched or not the case of the Valves with ease in a push-pull config.
Then in June of this year, I decided to put into a plastic enclosure, fitted the sockets to allow testing of ECC83 and during testing and with a typical school boy error damaged the Anode and Screen Supply output devices. Checking with a DVM they tested fine, however at High Voltage during Valve testing, they leaked. Ronald after contacting; sent me a set of transistors for the output stage free of charge and issue resolved.
The uTracer is now in its enclosure, fully functional in a very simplistic configuration. I removed the RS232 chip and wired in a TTL-USB module so it connects to my Mac osX using wine. The Laptop PSU is stuck to the top of the unit to reduce the clutter. Some pics enclosed. As uTracer fits my requirement, I have sold the AVO MK2 and have recommended uTracer3 to anyone who may need a Valve tester as the best/simplistic/cost effective diagnostic tool to have.

Excellent piece of kit, Excellent customer service by Ronald and Marie-José and a very happy customer and user of uTracer3.

Waiting in anticipation for uTracer4, with a higher Anode/Screen Voltage.

Apologies it took your mail shot for me to send you the feedback/testimonial. My worktop is a bit busy/messy according to my daughter.


3rd of August 2014, V.T, Mueller sent me an update on the progress of his uTracer.

Dear Ronald,

My apologies for (still) being late. I've been super busy. In about two weeks time life will become somewhat more normal again. Nevertheless I managed to almost finish the uTracer case. Labelling is still missing. Plus I think I have to do some debugging as the tracer appears to work except for I appear to see no amplification by the tube. But then this was one very short test with a 6L6GC in the middle of the night - just to have it tried one time after soldering the sockets and connectors for a few hours. As I mailed before: I will send you appropriate feedback, just allow me some more time please.

Thank you very much for your outstanding work and support.

Best regards

14th of July 2014, Karel Bartos from the Czech Republic used an old communist notice board for the wooden box of his uTracer!

Hi Ronald and Marie-José.

I built the uTracer quickly yet it had to wait for the first tests until today - and the device works! :)

The kit is fun to build and my guess is that even less experienced builders (while I am far from being experienced myself) than me can make it. My purpose was to keep it all simple and effective - money wise and time wise, while all I needed was a tool for valves in my audio and guitar amplifiers. As you wrote, especially for power valves it would be welcome to have higher anode voltages, but still. I kept the "banana design" and used exterior AC adapter. Also, despite you yourself reported problems with prolific chip in serial-to-USB, the cheap one I tried works just fine. Some guys made very stunning and retro and vintage designed boxes which I admire but cannot compete with, so to at least keep some spirit of history, my wooden box is made out of a communist army notice board which served for a presentation of a gas-mask in the 60's :). Well, now is the time to get familiar with the measuring itself.

Thank you again and keep the good work!

Karel Bartos

1st of July 2014, André Berwald spent his holiday finishing his uTracer, another satisfied customer!

Hi Ronald and Marie-José,

This passed weeks I had my summer holiday and among other (home improvement) projects, I spend some time on building a casing for the uTracer.

For the box I used the plexiglas (which can be found in old flat panel monitors). I glued the plexiglas together with "Hard PVC" glue.

The uTracer is working very well, I tested a lot of tube's I had lying around in my hobby room. I did not see any evidence of oscillating, so, I guess the ferrite I used is suppressing sufficient.

For the connection of the banana plug terminals I used FT37-43 with 6 turns of enamelled copper wire. For the interconnection of the pins of the tube bases, I used half of a FX1208 between each second tube base.

I have included some pictures of the internal of the casing and some of the first curves I traced. The viewing of one of my magic eye tubes with the Utracer (an EM4), I have placed on YouTube (for uTracer promotion ;-)

I am very pleased with this extremely useful piece of equipment that for sure is going to help me repairing a lot of vintage radio's.

Thanks again for this marvelous kit!

André Berwald

30th of June 2014, Henning Hoeberlin very nicely integrated his uTracer with an old laptop into a single piece of equipment.

Hi, Ronald, Hi Team,

it has taken a while, but now i have finished my µTracer. I have the µTracer Board, the µTracer Power Supply, and the Laptop Power Supply arranged in the Housing, and have mounted the Tube Sockets and the Matrix left of the Laptop.

Please see attached Pictures. The Laptop Power Supply ( on the right side ) is always on, when the mains is connected ( need this, because the Battery is dead ) and the µTracer Supply ( behind the µTracer Board ) is turned on by the Switch on the right hand side.

I have started to make cards with color codings, for different Tube layouts. Up to 5 Tubes with same layout can be arranged on one card. Using this method will hopefully avoid any errors.

Everything is working fine, and even the latest Software is running fine on my 256kB Pentium3 Laptop.

Thanks again , best Regards,


6th of June 2014, Aaron White of Emerald Sound end Vision is very satisfied with his uTracer!

Some time ago i read about the uTracer on Ronalds weblog and just had to get one. Well i can confirm all the rave reviews, it is a fantastic bit of kit! Working as i do in the vintage electronics field a curve tracer is a must have tool. The Tek 575 is an absurd price for a good one and it cant do half the things a uTracer can. The ability to instantly get mu, gm, Rp as well as many types of curves is wonderful. The kit supplied by Ronald is top notch with quite simply the best instructions i have ever seen. It made building the uTracer a real pleasure. Once assembled it worked first go and has been flawless. It is really accurate too. Ronalds communication and support when i did have a little problem were the best. I cant recommend it enough!

Aaron White

2nd of June 2014, Enrico Munaron’s uTracer looks very slim and professional!

Hello Ronald,

I'm happy to send you the photo of my finished uTracer! Sorry for the delay, but the work absorbs most of my time... Thanks a lot, now i can test all of my tubes easily! I decided to use a 24V Meanwell switching PSU (i've got one new and unused) but the output, although adjustable, was limited on the bottom at 21V, then i modified the feedback ring to fit and adjust the output around 19V. I've put all the things inside a little box, and result is very compact and usefull!

Thanks for all the work an passion you put in this unique project!

Best Regards

8th of April 2014, Chu () send me some pictures of his “vintage” uTracer, and some measurements of a mystery tube: TM15.

Hello Ronald,

I finally found some time to finish my uTracer project. Using a wood case to box up the uTracer kit and power supply. And add a adjustable voltage regulator to be external heater power supply.

For easier to use, I removed MAX232 and put an USB-TTL module for connecting to PC. The chip of this module is SiLabs CP2102, it works very well with uTracer.

uTracer is a quite useful tool for me, I've tested a lots of my tubes. Especial some unknown tubes in my collection or triode connected pentodes. For example, the TM15 triode is that tube I could not find any data. Right now I can use uTracer to test what kind of tube is it.

Thank you

Regards, Chu

27th of March 2014, Kevin Moulder’s uTracer is absolutely fabulous (I think)

Hi Ronald,

Finally finished assembling the uTracer and building it into a case from an early piece of equipment. Apart from getting the software to run on my XP PC, I had no problems in the population of the board and must compliment you on the professional approach in the making up of the kit and the care and attention in setting up each stage of the board development.

I made a few changes to the design and removed the LED’s off the board and mounted them on the front panel. The Micro reset jumper was removed and a reset button mounted on the front panel with a 4k7 pull up resistor to 5 volts. I tried to cover the full range of tube bases and ended up with 14 tube sockets. In the layout for the tube sockets I used your recommendation of looping back the wires for each of the pins and added inductors in series with each of the connectors. Please feel free to use the attached pictures in you testimonial column.


Kevin Moulder

21st of March 2014, Gert Bluemink’s uTracer is simple, but effective!

Hallo Ronald bij deze dan even 2 foto’s van mijn uTracer.
De foto’s tonen even een proefopstelling en ik had nog geen tekst aangebracht op het kastje. Als radio amateur en liefhebber van buizentechniek heb ik geen uitgebreide buizentester nodig. De 4 buisvoetjes op de foto volstaan in mijn geval. (en anders kan ik altijd nog een verloopstekker maken). De 19V haal ik momenteel uit een regelbare voeding. Eind 80-er jaren heb ik MTS-elektronica gedaan. Opgegroeid met de 8088 microprocessor en buizen waren allang uit de tijd. Misschien komt daar juist de interesse in die schitterende buizentechniek vandaan, aangezien ik in de modernere technieken al genoeg was onderwezen….

De uTracer functioneert hier naar behoren. Met Windows 7 geen enkel probleem gehad om de software te installeren. De bouw van de uTracer viel ook niet tegen. Door de mooi apart verpakte onderdelen hoefde ik niet ellenlang te zoeken naar het volgende weerstandje. De bouw spreekt voor zich en de handleiding was zeer duidelijk. Natuurlijk helpt mijn MTS-elektronica achtergrond en het soldeerwerk als radioamateur wel een handje mee, maar ik verwacht dat e.e.a. ook goed is na te bouwen door iemand die alleen al interesse heeft in de techniek, en al enkele bouwpakketjes heeft gesoldeerd. Een goede soldeerbout en goede punt (in mijn geval Weller WTCP met een scherpe punt nr. 7) en zo’n klein kniptangetje dat het af te knippen pootje vast blijft houden, zijn erg makkelijk bij dit soort projecten.

Met vriendelijke groet, Gert Bluemink PE1RTC

20th of March 2014, Laurent Szymkowiak made a very nice top-plate for his uTracer.

Dear Marie-José, dear Ronald,

It's quite a while that I purchased my uTracer kit but I finally got the PCB fully integrated into my chassis. Was not so easy to manage my time between business trips and my 9-months son ;)

I send you a few pictures of the result. I just modified the position of the heater PCB since I took the pictures. Yesterday I tested it with several tubes and the uTracer works really fine! I will now make my personal library of tube data and will add the SPICE models. I think the uTracer community will change radically the tube testing approach! There is no real concurrence for hobby tube testers.

Just a few words to the build itself: I took a while (actually this is what took me the most of the time in this project) to think how to integrate the PCB in a usable way. I checked the references posted on the uTracer website, I checked several other testers and finally came up with the same approach as yours Ronald. In the end this is a tube tester, which needs to primary focus on the function and the ease of use. So I integrated your concept with mini banana plugs as the risks of injury is limited here. I added some plugs to perform the calibrations (2x for power supply voltage check and 2x at the cathodes of the booster capacitors). I can also use the power supply testing plugs for external supply if needed. And because I will mostly test "usual" pre-amp tubes like 12AX7... and power tubes like 6V6... I hardwired 2 sockets (the 2 bottom ones). That limits the possible errors. Some of the other builders concepts are really impressive but too complex to my taste... That's it! By the way the top plate is a 4mm aluminum plate and the box is simply a good quality plastic junction box. I had a aluminum one but this is harder to work on (for the holes in the back) and that would have been too heavy in the end. Once again I'd like to thank both of you for the efforts you bring in this project. You can count on me for the uTracer 4 :)) I will now enjoy my tester and will feedback to you to maybe extend the wishlist ;)

Best regards,

5th of March 2014, André Berwald’s uTracer came alive!

Hallo Ronald en Marie-José,

Vanmiddag heb ik de laatste test uit de bouwhandleiding afgerond.
Het bouwen ging voorspoedig en ik heb de handleiding als een perfecte leidraad ervaren.
Het enige wat ik even gemist heb was het insolderen van de header voor het programmeren van de PIC processor (dat had ik natuurlijk samen met de connector for J3 moeten doen in stap 5.18).
Voor de rest ben ik geen gekke dingen tegen gekomen en iedere test en calibratie ging prima.
Nu ga ik nadenken over een geschikte behuizing, eerst nog maar wat lezen op jullie website. Dank jullie wel voor het mooi verzorgde bouwpakket.

Met vriendelijke groet,

André Berwald

17th of February 2014, Jim Wigley finished his uTracer

Hi Ronald

The attached picture shows my version of your marvelous uTracer. It is very basic only three sockets for B7G, B9A and Octal. These cover all the valves I use in my guitar amps. The case is a cheap plastic one from Rapid Electronics 278x174x60 and only costs £10. I use the uTracer to test for go/no go in new valves before inserting in amps. So far I have detected two dud new valves.

I enjoy reading your various blogs, but I am not qualified enough to contribute to the discussions.

Rgs Jim

15th of February 2014, Ignacio Zozaya Suárez took the effort to write an extensive review, and sent a few pictures of his uTracer with record amount of sockets.

Hi Ronald, Marie-José and community of uTracers,

Just wanted to contribute to the growing uTracer family sharing a couple of pictures and some experiences which will hopefully be useful to many. First of all, I cannot thank you enough for such an outstanding piece of engineering and art. The uTracer works like a dream and is lots of fun to use!

The uTracer is such a valuable piece for tube enthusiasts that it really deserves a good casing. This is a separate project in itself, requiring lots of creative thinking and planning, but not free of risks. Of course everyone´s priorities and skills are different, hence such a broad spectrum of implementations, and for that purpose the Testimonials page is a great source for inspiration and out of the box ideas.

In the past I used to trade on tubes, and although I am no longer in that business I still stock about two thousand samples awaiting to be tested. Thus, my implementation was conceived having efficiency and flexibility in mind, this ultimately leading to a number of features that may differ a little bit from most of the implementations seen so far. I decided to go for a direct wired approach rather than a configurable setup using cable jumpers or switches. The reason behind was that I wanted the tester to be operated as easy as possible, low setup time, low risk of misconfiguration, and without having to resort to a tube manual for looking up pinouts. The immediate consequences of such design choice are the large number of tube sockets to be perforated in the steel box and the daunting internal wiring job. With about 30 sockets most of the common and not-so-common tubes can be tested directly. Triode-Pentode tubes like the ECL86 or the 7199 have also been accommodated by using separate sockets for each section.

Then, bench tests showed that the internal heater supply can be the cause for lower than normal measurements when heater current demand goes above half of an amp in RMS terms (e.g. an EL34 demanding 1.6A of heater current would measure Ia and Gm about 10% lower). In order to overcome this shortcoming, and to be able to test low voltage high current heater tubes like the 2A3, I installed external banana plugs and a switch to choose as needed between an external power supply and the internal one. This has proved to be a most useful feature, which I strongly recommend other prospective builders. Next to it there is also a connector with direct access to the tube electrodes for additional testing flexibility.

Everything worked fine until some hardware issues arose which I would like to share. The high voltage switch failed twice (once the anode one and once the screen one); on both occasion this happened while testing rectifier tubes (a 5U4G and a GZ34). We will probably never know what really happened, but I will not be testing more rectifier tubes for sure! Once the silicon bits in the switch were removed, forensic analysis revealed that the only failed component was the PN5416. My hypothesis here is that under short conditions of the load, the PN5416 may dissipate over its 600mW limit while providing base current for the MJE350, or alternatevely exceed its Vce-max (I should probably mention here that the socket array makes intensive use of ferrite beads therefore making the tube under test a moderately inductive load), causing it to fail before the MJE350 does. Although the MJE350 is dissipating at this point significantly more power than the PN5416, the latter is much more fragile and may actually collapse first. Incidentally, if you need to replace the obsolete PN5416, its modern equivalents are the MPSA92 in Europe and the 2N5416 in the US; they also seem to be marginally more robust too.

The GUI runs on my MacBook Pro OSX Mavericks using Wineskin. I followed the process provided by Mike Foo (instructions found in your FAQs section), which is very easy and straightforward. The USB RS232 converter uses the Prolific chip; I have to say that this type has not been the cause of any problem to date. I am tempted to install a bluetooth-UART adapter for total simplicity.

The Quick Test is a great feature of the GUI. Plate current, gain, transconductance and internal resistance readouts are in practice the only ones which are relevant and can be properly interpreted. My only two suggestions here would be to dismiss or hide the rest of the calculations as they are rarely needed, and also to be able to store in the test setup datebook reference values for direct comparison against the readouts.

Interestingly enough, most of the fun using the uTracer comes from testing all those tubes that had been previously tagged as faulty, weak or suspicious. Whether it was low emission, mismatching, or structural damage, the uTracer tells the whole story behind each one!

Best regards

Ignacio Zozaya

11th of February 2014, Lars-G. Lundelin from Finland finnished his version of the uTracer

Hello Ronald

I had to postpone (due to circumstances) the project with my µTracer-project owing to a fatal mistake during testing the Tracer a few months ago. Now, a couple of days ago, I commenced the project again and got the machine in working condition, and it seems to be working nicely. The power supply is made up from an old Cipher tape drive for an XT-computer, although the switched mode power supply was replaced by a more conventional transformer-rectifier with a voltage stabilizer, with options for 25 and 35 volts tube heaters. Must say that I'm very pleased with this gadget and obviously there are more pleased µTracer builders here in Finland according to all appearances in the SRHS forum. Three pics will be attached

Lars-G. Lundelin

9th of February 2014, Juha Niinikoski sent a few pictures of his very compact uTracer box

Hello Ronald
The uTracer is now boxed and working well. Some pictures attached.

My solution was to use rather small box to save table space. Tube socket modules I am going to build more as required. Rare / one off measurements can of course be done with just alligator clips and test leads.

2nd of February 2014, Tuukka Kalliokoski from Finland wrote me a very praising review!

Hi Ronald and Marie-José!

I have succesfully completed building the uTracer, and want to thank you for very good instructions and clear packaging of parts! This is maybe the best documented kit project I have ever built!

I had a previously self made tube tester with manual adjustment of grid and anode voltages. The uTracer board fits nicely into the tester case, with a Dell laptop 19V power supply. A switch selects manual or automatic operation.

Thanks again for this great project! I sure will recommend it to everyone asking!

Tuukka OH3MVV

23rd of January 2014, Len Sherman sent a few pictures of his uTracer build

Hi Ronald - As promised, here are some pictures of my uTracer build. It's pretty bare bones compared to some of the impressive builds on your site, but it is a fairly simple design that went together without difficulty. I got the box from a local surplus store. It had some extra holes, but it included the front panel power switch, fuse holder, power cord socket, and some front panel LEDs, which all gave me a little head start.

Since the box was fairly large, I mounted the laptop adapter inside. I cut open the top of the adapter to allow a little more air cooling since the adapter would be living inside the case. I mounted a USB serial adapter in place of the MAX232. If I get some time, I may try a bluetooth serial adapter so I can toss the USB cord, but it's not a high priority.

All is working well, but my eBay tube sales have slowed now that I've worked my way down to the more mundane parts of my Amperex stash. Still, it's been fun and I easily payed for the uTracer with the proceeds.

Best regards - Len

23rd of January 2014, The uTracer of Juha Niinikoski (Finland) has come to life!

Hello Ronald and Marie-José

kit arrived two days ago. Kit went together without problems. It took few hours and some glasses of wine. In this RoHs era it was pleasure to do the soldering work with tinned pcb and old good tin/lead solder. Some resistor and diode decals are "tight" what you may already know. However no problem if you carefully bend and form the component wires. Picture attached. I may send more and better pictures after the system is boxed if you like.

First impression is that uTracer is excellent equipment. If you do anything with tubes uTracer is a must have item. User interface is very intuitive. As mentioned above try first read manual later works well. Your documentation quality is unbelievable high. Wins most commercial instrument documents 10:0.

Best Regards
Juha Niinikoski / oh2nlt

15th of January 2014, In five days Anders Magnusson finished his uTracer and boxed up and all!


I have just finished with the first implementation of the uTracer, currently placed in an ugly wooden box. The kit was delivered 5 days ago, and since it was really simple to build it with help of the good instructions everything went as on rails.

It works amazingly well, I have already checked ~50 tubes to see both their quality and their behaviour in ways that are not usually documented (grid current etc...)

One discovery I made: corrosion in the tube sockets might give very interesting results... :-)

Great work and many thanks!

-- Ragge

8th of January 2014, Laurent Szymkowiak sent me a nice testimonial!

Dear Marie-José,
Dear Ronald,

Just wanted to tell you that last week end I managed to finalize the build of the kit. I tested everything and the uTracer is working fine. I now need to work on the integration into the housing I foresee for it. I'm still not sure how I will exactly finalize it. I'll send some pictures of the result later on. I'll also start a website to collect all my different projects.

I wanted one more time to use this opportunity to thank both of you for the efforts and the time you put into this kit. I think that one has to make it on purpose to build it in the wrong way. The construction manual and the several tests along the build should be taken as a reference by many other "renowned" kit builders. The website is one of the best documented I came across. I can just say well done. I also have family in the Netherlands and you guys bring it! Keep on doing like this!

Best regards, Laurent

7th of January 2014, Ian Rodger used the Xmas holidays to finish the case for his uTracer!

During the Xmas holidays I finally got round to sorting out a case for my uTracer. Here is a picture of it with a faulty EL34 under test. This was a (new in box) tube that I knew to have a fault, set aside some time ago when building an amplifier. With the uTracer it is immediately obvious that it is not correct, although I am still trying to work out what has failed!

Best regards, Ian Rodger

6th of January 2014, Mario St From Italy finished his version of the utracer with direct wired sockets.

26th of December 2013, Henri Béguin turned his uTracer into an amazing portable instrument!

24th of December 2013, Robert Hewitt sent me a few pictures of his nice and tidy uTracer on Christmas eve 2013.

24th of December 2013, Walter Harley from Cafe Walter Audio sent some nice pictures of his uTracer enclosure.

I got my uTracer enclosure built! Here are some pictures. It all fits in a steel enclosure of 178x127x51mm - a bit snug, but seems to be working well. The PCB sits about 3mm from the bottom of the enclosure, mounted from the top on nylon standoffs.

Merry Christmas,

21st of December 2013, Albrecht Schwaderer turned his uTracer into a beautiful instrument with a definite vintage look!

Hello Ronald,

after receiving the µTracer I've done some measurements with the great Version 10 from you. Now all my wishes are fulfilled. I like the Quick test and also the possibility to store the pinning of a tube, and the measurement setup. This is the optimal addition for my version of the µTracer.

But have a look to the pictures. Now it is time to say thank you to you, for your great ideas your support and your patience and endurance. Some explanations To connect the PCB to the TUT I've constructed and build a crossbar switch. With a normal 4 mm connector (Banana plug) get the horizontal and the vertical rail linked. The left (horizontal) side is numbered from 1 to 10 and connects the socket pins to the crossbar switch. The right side is linked to the connector right. This is for an adapter box with sockets which haven't found place on the front panel. The down side is linked via the vertical rails to the PCB in the order H+, H-, C, A, g1, g2, Uca (C18), Ucs(C14). A small DVM is also installed with four ranges Usupply Ug1 Uca Ucs.

Greetings Albrecht

4th of December 2013, Egon Penker sent me a few pictures of his uTracer implementation

Hi Ronald,

now the uTracer fix is installed and it works to your complete satisfaction. Thanks also again for the PIC replacement! I have attached 3 photos of the structure and a protocol in the supplement.

So thank you for the really excellent uTracer3 and all the best continue also to the hardworking wife.

Sincerely, Egon Penker

4th of November 2013, Spence Barton reported his uTracer working

Hello Ronald,

I finally had a free day yesterday and assembled my u-tracer. You have really made it easy with a complete parts set and perfect assembly instructions.

I haven't built a chassis for it yet, but I had to clip some wires to a tube socket. I am interested in tubes with remote cutoff characteristics. I have attached my first comparison of curves from two different tubes. The dashed lines are from an ECC88 and the solid lines are from a 6BC8 which has a moderate remote cutoff characteristic. This if very clear from the curves. The tubes have nearly the same gain but obviously the ECC88 has higher Gm.

What a valuable tool you have given us. Thanks,


2nd of November 2013, Rüdiger Waltz sent me an update on his uTracer

Hi Ronald,

thank you very much for the update of the GUI. The Quick Test is really a great feature !

Enclosed two pictures of the actual status of my uTracer. I built it into a first aid box for cars. It is plastic and easy to work with. There is enough space for the power supply, the pcb of the uTracer and the most often needed tube sockets.

The pins of the tube sockets are numbered clockwise and the connections are made via banana plugs as you see.

Unfortunately I have actual no ferrite beats at hand and so the shown EL84 is oscillating heavily even if the wiring is done according your weblog. This results in bended curves. I could stop it by a condenser from cathode to anode but this is not a general solution. I will keep you updated.

Best regards


21st of October 2013, Martin Manning finished his very nice and compact uTracer implementation

Hi Ronald,

I'm pretty excited about these new features you are working on for the GUI. I can't help thinking that it would be nice if you could get paid for all of this work you are doing though. I don't think that uTracer owners would mind paying for a SW upgrade if it adds some significant capability.

I have been making progress on my uTracer after a long delay in selecting and receiving the hardware. The attached pictures show the assembled unit. The tube socket connections are the nine banana jacks arranged in a circle, which makes it easy to translate data sheet pinout diagrams into a patch-cord set-up using standard color codes for the electrodes. A 6V6GT set-up is shown in the photo. Use of stacking banana plugs makes it possible to connect more than one tube pin to any one uTracer terminal, as for simultaneous tracing of a dual triode, or making the g3-cathode connection on an EL34. I went with a direct USB-TTL connection, which is via the 3mm audio jack on the right. Also, you can see that I am locating the two status LED's on the panel, which means a pair of leads for each one with soldered connections to the PCB. Removable connections (like the Tx/Rx) would be a better way to go, but I don't think the spacing of the LED pads is right for that.

A couple of uTracer owners have mentioned using a USB-TTL adapter rather than the standard USB-RS232. I wanted to go this route to eliminate the bulk of the D-SUB connecter and cable end. I chose the FTDI TTL-232R-5V-AJ, which has the converter chipset built into the USB connector, and a 3mm TRS audio plug at the TTL-end. Using this cable requires bypassing the MAX232 TTL-RS232 interface and connecting directly to the PIC’s Tx/Rx pins. A very convenient way to do this is to remove the MAX232 from its socket, and install jumpers from socket pins 8 to 9, and 7 to 10 as shown in the close-up photo. These were made from 0.024” (0.6mm) component lead clippings made U-shaped by bending them over the jaws of small long-nosed pliers. The same board-mounted connector is used, with the same Tx, Rx, and ground pin locations.

There is one odd behavior I have found with this arrangement, which is that with the cable connected and the uTracer power off, the “power on” LED glows at about half-brightness, and similarly the “HV on” LED will glow if the uTracer power is shut off after a test while the cable is still connected. Normal function of the LED’s is restored when the power is switched on, and I have not observed any operational issues.


In the meantime Martin has the GUI running on his Macbook. He wrote a great write-up about his experiences Read More.

Follow Martin’s adventures on “The Amp Garage.”

20th of October 2013, John Walton wrote an extensive review in the Newsletter of the New Jersey Audio Society (reprinted with permission).

15th of October 2013, Mark Jacobs sent me a few pictures of his stunning uTracer.

Hi Ronald,

It has taken me some time to finish my uTracer in a finished form. Since I do test larger power tubes such as 6336, 211, 845 etc. I needed to incorporate a more robust power supply and address some of the issues in testing DHT tubes. I incorporated 2 TDK-Lambda HK100A-24 power supplies, one powers the uTracer circuitry at 18.5V, the other runs at 24V for the auxiliary heater supply. They are commonly sold at auction sites for very little and can supply up to 4.5A. The heater power supply is switchable between the uTracer and the Aux. Supply by a hard switch, but the Aux. Supply and V/A display turn on when the uTracer heater is activated by the software. This is controlled through a SCR opto-coupler. The Aux. Heater supply also incorporates a 10 second soft start board. Communications is handled through a FTDI female DB9-USM adapter, so a simple USB cable can be used easily. Still have some issues with the FTDI adapter and also their cable working with older XP laptops, which seems to be a windows software problem.

I have fashioned the selector after the AVO valve testers, and uses the same tube data tables for the pin selectors. Although the rotary contacts are rated at above 3A, many of the sockets are hardwired to the Aux. Heater supply, so larger power tubes can be tested without damage to the rotary switch. The sockets use a wiring pattern similar to the AVO Valve Testers, but includes ferrite beads at each lead to each socket with the exception of hardwired heater pins. I did incorporate a grid gas test feature, although I am still thinking about incorporating a leakage tester. The upper faceplate and lower circuitry and power supply separates easily with detachable connectors.

The case is a standard Pelican 1450 which is fairly compact and fits all the electronics ( hopefully will have enough room to incorporate a uTracer 4 if it materializes). I designed the faceplate and had it fabricated by Front Panel Express ( They do very nice work at reasonable cost and their design software is free, so there is a fair latitude in what you can do.

So far everything works well and as expected, but I haven't tried any of my larger power tubes and still making changes to the adjustable power supply. On a separate note, I was wondering if it is possible to download other data parameters such as GM when saving the tube data, and if in some future version of the GUI one can record (retain) more than one curve trace for comparing dual triodes or two tubes.

Anyway, slowly getting there and appreciate all the work you have done and are still doing on the uTracer.

Best regards,


5th of October 2013, Tomas Klika from Prague sent me a few pictures of his awesome uTracer with a DIY matrix board!

Two detail pictures of the construction of the switch board.

Hi Ronald,

How you can see on attached snaps, the uTracer is finished and works perfect. I have built in the whole thing in old case of the SCSI HD. Unfortunately I can`t use the nice power segment inside for low voltage (12V).The interface is switchable USB - serial and USB finally works ( of course, silly things, the erratic contact on small PC board connector of converter - solved with iron). It`s possible to connect the external lower power for heating, but I did`t doubled the circuit with L/C, make one cut on PC board and connects it over switch. The problem with low voltage for heating is, how you suggest, partly solved. Generally still remains the crux with voltage of heating, I measured repeatedly tubes with 6,3V/0,2A with rectified external power and the curves matched by setting the uTracer on 1V more. I understand, then some kind of calibration is here difficult, but the difference to math seems to me to big. With the low voltages is the situation/difference even worse. Here is really a little painfulness, maybe I fix the table for various tubes for correction the setting. On the other hand the direct external power for heating fix all. Back to construction, I want to get rid of cables with banana and solve it with banana contact matrix, but it was the most time-consuming thing at all, cutting fifty Cu tubes, PC board, drilling and so on,(layout available). But it works good and that way is possible to have cards simple connect the tube and for me most important, to notice data of tube directly on card (I don`t know sometimes et evening what I ate to breakfasts :) ). Finally I have copied the cartridge system for sockets, but with Scart con.

Ronald, thanks a lot for all you did and do for uTraser and waiting impatiently for your next ideas and solutions.

The greetings from Prague in indian autumn time.

Tomas Klika M.D.

29th of September 2013, Ale Moglia posted a very nice review of the uTracer on his site Bartola Valves.

Click here to read Ale’s review

20th of September 2013, Mathieu Melenhorst made a nice portable uTracer.

This is my µTracer on the left-hand side in the aluminum case with the Arta measurement box. I decided to use the same measurement connector set-up as Ronald suggested. The only difference is that the four sockets on the lower right side are connected to C13 and C18 to facilitate re-calibration. I included separate sockets at the rear that are in parallel to the power supply. The Octal and Noval connectors will do (for now).

Though I hope it’s not necessary, I included a power fuse and I connected a power diode across the power plug on the PCB in case I forgot the + and -. I hope (and I think it’s safe to assume) that the µTracer will be forgiving when -700 mV is applied in this case.

19th of September 2013, Peter Buckle send a few pictures of his stunning implementation of the uTracer (the first one in Africa!).

Hi Ronald,

I eventually got the opportunity to take some pictures of the completed uTracer.

The build of your kit went with no problems at all, and was in fact the easy bit. The design, components and construction manual are all top class. The manufacture of the enclosure, the facia plates, the engraving, and the switching arrangement, were what took the time. Pareto was right! The final 20% took 80% of the time. I decided to use a switching arrangement similar to AVO as I have a copy of their Valve Data manual, with all the switching codes for the various valves. As my current use of valves is for the guitar amplifiers I build ( the BSonic name on the tester panel), I only needed 9, 8 and 7 pin sockets. However, I have arranged them so that I can add other sockets if the need arises.

The finished unit works extremely well and I am grateful to you for the work that you have put into the development of its heart. I look forward to uTracer4 with interest!

Kind regards,

Pete Buckle

13th of September 2013, Richard Bergquist send a few nice pictures of his uTracer.

Hi Ronald,

the uTracer is finished, it works very nice I've tested many tubes, fried some heater fuses on some EL34s I have looked at your circuit, it appears to me that the 1-1/2amp fuse protects the power supply. I have increased to 2 amps. The face plate was done on my CNC router. The box came from MPJA. I only installed three sockets, when I need a different style I will use the octal and build an adaptor. I noticed while doing my first tests with just a socket and long wires some times I would get oscillations so I wanted to keep the wiring to a minimum, I had problems with loading the software to my XP computers, it runs fine on Windows7, I have tried the other version made by your friend but still like yours the best. The only changes I would consider is go to a USB instead of the db connector and add a heater current limiter. I love your uTracer thanks for bringing this to my shop!

20th of August 2013, Murray Johnson reported: “Another uTracer springs to life!”

Hi Ronald,

I just completed the build of the uTracer. This is a beautiful instrument! It does everything I need to compare tubes. Thank you so much for all of the time you put into the design, putting together the parts and the construction manual. This must have been a labour of love - and we are all better for it.

From one engineer to another - very, very well done!

Much respect,


19th of August 2013, Christian Verdier (F6HXH) sent a few snapshots of his uTracer.

Dear Ronald,

I have just finish to build the Utracer. The manual is perfect and I had no problem to start the complete circuit.

In order to learn how i can use the Utracer, I have build a very simple set of two tube sockets with a set of miniature banana plugs.

You'II find attach some pictures. Now, I am working on the final version of the case.

One more time, congratulations for your fine work.

Best regards

Christian Verdier F6HXH

15th of August 2013, Claude Welschbillig sent me a few pictures of his very fine uTracer implementation!

1st August 2013, Ron Soyland, who makes his own replicas of Lee de Forest Audions and other vintage tubes, sent me a few pictures and some comments on his version of the uTracer. Read his report and visit his site or You Tube videos!


I finally got all of the uTracer hardware finished and working correctly. With my poor eyesight, the socket and swtich wiring was a bear! It all works fine now and I really like it a lot! Here are some details on what my implementation look like.

The uTracer itself was built into an aluminum case to afford a solid shielded box. The power supply is a built up 19 volt 5 amp linear type because the laptop module didn't have the current capability to operate some larger filament amperage tubes. The filament supply is an isolated power inverter that outputs 19 volts and 6 volts at 4 amps. The control for the output is direct duty cycle so the software works directly with the supply with no modifications. The low (6 volt) range of the supply is selected by a front panel switch and is used for testing tubes with low filament voltages. (1 to 4 volts) The isolated supply allows testing of old type filament cathode tubes. The high (19volt) range works for tubes with 5 to 15 volt filaments exactly as in the original uTracer design. The two ranges allow setting the filament voltage more accurately at the 1 to 4 volt range for low voltage tubes.

The socket box was made from two old tube testers. A Sencore TC162 MIGHTY MIGHT tester was used for the front panel and the modern tube sockets, which are already wired pin for pin in parallel. A Superior model TW-11 was used for the lever switch mechanism, the four big pin sockets, (not present on the TC162) and the wood cabinet. The Sencore steel cabinet could have been used directly but I like the solid oak wood of the TW-11 much more so it was worth the effort to cut the box down to match. It was not difficult since one dimension of the box was already the correct size.

The lever switch mechanism was mounted through a hole cut in the TC162 panel with a saber saw. The same with a small panel with the 4 big pin sockets, which mounted where the meter once was. The slide switches of the TC162 were wired in parallel for the screen supply pin selector, and the lever switches used for the grid, anode, and cathode selectors. A six pin connector connects the switch box to the uTracer. By having the switch box connected separately it can also be used with other types of tube testers, and also allow the uTracer to be used independently when sockets are not needed.

The uTracer is shown being used to test an experimental triode which is connected to the vacuum system. The multi-trace function of the uTracer allows parameter changes to the circuit, and then plotting the traces one after the other on the same screen. Ideal for seeing how different parameters affect tube behavior.

The test shown is of how degree of vacuum affects the gain of a tube. The top two traces (almost overlay each other) are at 6x10 -6 torr and 10 -5 torr. Note that there is very little difference in characteristics below 10 -5 torr. The next traces are at 5x 10-5, 10-4, 5x 10-4 and 10-3 torr (! micron) pressures. Note that at pressures above 10-5 torr, the response of the tube becomes progressively worse until at 1 micron the emission is virtually gone.

This test only took a few minutes with the uTracer, mostly waiting for the pressure to change. Doing it by hand, plotting the points on graph paper, was totally impractical, taking 30 minutes or more and being prone to error in reading the graph paper divisions.

You are free to use the photos and blog in your advertisements if you like. I will also update my website with a big section on using the uTracer after I become more familiar (an expert!:-P ) with the operation of it. By the way, I have noticed some more software "irregularities." (ugh!) I will store them all up for one list of stuff for you to do while you are bored with nothing else to occupy your time!:-P


Visit Ron’s website
Watch on YouTube how he makes his won Audion Tubes!
Download the circuit diagram of Ron’s low voltage heater supply.

25th July 2013, Peter Håkanson sent me a few pictures of his uTracer. Peter very cleverly uses a special “connector key” to connect different tubes to the uTracer!

Once again : Thanks for a very well designed kit !!

Peter Håkanson

14th July 2013, Paul Barker sent me a few pictures and a very enthusiastic and personal account of his experiences with the uTracer.

Paul testing a PM5X in his “man cave.”

You have blessed my life so much designing and making available the uTracer. When Nick first brought it to my attention I was at a very bad time financially. But since then I have had decent work sub contracting to British Gas. The contract will have an end, but this amount of money I could justify to improve my state of mind. Playing with valves is my hobby. I have always designed my own circuits from characteristic curves. Then I have had to make adjustments  as the valves I own don't perform as the characteristic curves would predict. Now I can trace the curves and design my amp accordingly. I can select closely matched valves and make better amplifiers.

Before I build the uTracer into a box I am using it with temporary connection to the valves. Now I have begun testing a bunch of British 4 pin 2v directly heated triode valves. Some do have markings and some do not. So far I have some duds, but I have some good valves. the habit in the period they were made was to use the X axis for grid volts Y axis for anode current and the curves were anode voltage. It is much easier to design an amplifier using the modern curves of grid volts and XY anode volts / current. So I am able to make graphs of much greater use to me. I can calculate from the traces the three characteristics so key to deciding what to use a valve for. 

When dealing with very old valves like this it is first a matter of finding one with the characteristics I need and then looking for another. The tracer helps me evaluate all the valves marked or unmarked until I find a pair.

Some of my other old valves like PX4 and PX25 have not stood well the test of time. But better I know that and work with them accordingly.

I can also test what up to now in the diy valve audio community has been myth and conjecture. Such as the 1619 is meant to be like the 6v6 or some say between the 6v6 and the 6L6. Other places they say it makes a suitable replacement for the 45, on the basis of filament requirements. The benefit over the indirect valves is the supposed "better" characteristics of the directly heated valves, though this is a mute point.

The uTracer doesn't lie. It can upset but it is a very important tool.

Confining it safely to a box is an ongoing project. 

Paul Barker

Ps: Follow Paul’s progress on the Audio-Talk forum

11th July 2013, Mike Watson used a MX-494A/U tube adapter kit as a case for his uTracer, an excellent idea!

Hi Ronald & Marie-José,

Just a note to let you know I have built the utracer board.
Everything went smoothly and all stages worked first time!
An excellent kit, very clear instructions, I had no trouble at all ...
I just need to build it into my box of valve sockets.

Many thanks,


4th July 2013, Marcel Bernards uTracer looks absolutely stunning!

I finished my build last weekend and did some tests and it turned out just great.

The inner guts. I used old style wiring pushback wire and oil sleeves for the switch and tube socket wiring stuff. Note the red insulated dots at the tube sockets. Those are the ferrite sleeves. I shrink insulated them too, because they measured about 2-3K resistance and I used bare wires to mount them.

It's incredibly tight and I thought the case profile was a bit too low, but with some fiddling and proper positioning of the PCB I managed to fit the stuff in there. The row of 4mm banana plugs fits just between the large caps on without touching and keeping proper distances because of high voltage levels. For safety I also added an sheet of plastic between the panel and the PCB.

I used Abacom Frontpanel Designer to design the fontpanel and I printed and sealed it in plastic and glued it on the aluminum panel.

28th June 2013, Joachim Mattisson reported his uTracer working:

Dear Marie-José and Ronald,

The uTracer kit arrived yesterday.

Believe it or not. But I have already finished the kit. Tests and calibration according to Ronald´s manual are completed successfully. It is on outstanding manual and I followed it by the letter which made it easy to build the uTracer.

I'm very grateful for all you have done to make it possible for people interested in vacuum tubes to get a nice tracer.

Best regards,


26th June 2013, Brian finished his version of the uTracer:

Hi Ronald,

I have included a couple of pictures of my uTracer built from the 3.0 kit you sent.

I must say the components are great and packaged so well to identify them, I built the board over a week in the evenings following the instructions and tests. I have built a few kits in my time and the instructions were faultless, I particularly like your process of building the pcb in the order so you can test each section as you go and then fault find if it down to component level, only one in my case (my fault).

I have used it to test all the valves I have (for some 40 years) to find only a few were not working and some were soft. I like the heater warm up process it  gives you a chance to abort the testing if its drawing to much current as I found with an 807.

In the pictures you will see your board with a small brown Vero board, this the power i/f, fuses and allows disconnection of the valve bases from the electronics when adding another valve base to the unit.

The only additional item to your design, I have extended the reset button to the outside which is the final stop if any problems or hangs occur, I have used this when the interface hangs or the heater warm-up stalls for some reason. 

I love the blog and the detail you go into on each of the sections of the tester and the V4 explanations, these have enhanced my understanding of boost converters and HV measurement.

Many thanks for all your time in the development and cataloguing of the results

Kind regards, Brian

26th June 2013, Leon Glas gave an update of the build of his uTracer (in Dutch):

Beste Ronald & Marie-José,

De uTracer is nog niet helemaal klaar, het testen van el34 pin compatibel el 84 6sn7 6sl7 en ecc8x (schakelaartje voor de triode helften) werkt. In de deksel wil ik meer verschillende soorten voeten zetten, maar aangezien ik het meeste met gitaar versterkers hobby zijn dit de meest gebruikte. Aan gezien bij m'n  avo ct160 de anode stroom meting en de steilheid meting niet meer betrouwbaar werkt is dit een erg mooie aanvulling

Met vriendelijke groet Leon Glas

25th June 2013, Thomas Stepanek finished the build of his uTracer in no-time!

Ok here some picture from the building and the package. The pictures from the housing follow later I have to do some labels on it and other cosmetic stuff.

The building and testing was really fun and makes me very happy. The instruction manual is written were detailed and good to understand. I don’t find any errors at the manual. This day I made some tests and draw some curves with the tracer. I have to figure out how this all works and how I do the right measurements of my tubes. Finally I know now that many of my old radio tubes that I store in boxes are in bad conditions. I try also to understand the software and the communication technics for this project. I repeat maybe, but a lot of work did your husband with that project, and he did really a good job hat up for this. The next day I have to read all the instructions and tips on the website carefully to understand the idea of your husband in all parts of the circuit.

So that’s enough for now. Greetings to you and your family.


23rd June 2013, Jay Moodley send me a few pictures of his build of the uTracer

Hello Ronald and Marie-Jose,

Your message is well times as I am busy finishing up the construction of your U-Tracer. My 12AX7 bench test has worked well and I am extremely satisfied with the quality of the design and the attention to detail you have put into this project.

After much research, I decided against purchasing and restoring a traditional Tube tester and since I could not afford the fabled Tektronix curve tracer, your design was by far the best option for me. On the one hand, I expected the build to be much more complex than it turned out to be and the other, I underestimated the amount of time required to produce a finished product.

I am in the final stages of doing drawings for my plug in test modules (Each socket type will have it's own adapter) and hope to have this done by this evening. (Electric storms have put my gardening plans on hold)

Here's a few pictures of my build....

The first shows the Hammond enclosure on our DIY CNC machine. Note that the Banana jack holes were milled to their actual shape instead of drilled in the conventional way. I also made provision for a switch to select between internal and external heater power.

The next series of pics show the internal build detail and the last shows the completed product. I still need to fill the engraving with an enamel compound.

Thanks for your tremendous effort and support to the DIY community.

Jay Moodley

21th June 2013, Michael Watterson, Gave me an update on progress on his uTracer. He certainly broke the record of the number of different sockets!

Attached is my valve base panel. The 10 off circular arranged 2mm sockets go to tube bases. The two middle jacks bussed to top cap jack socket pairs and pin 11, 12 on a few sockets. The straight row is the connections to uTracer. The row of holes below will be for auxiliary voltages / signals. The 2mm patch cords are stackable. I have the un switched Va and Vs to the bottom row sockets as well as 0V (effectively -19 wrt to cathode).I will add LT for battery valves and higher volts for series or 117V heaters. I’ll add a +V offset to bottom row of the Vg signal for DM160 (or similar Russian one), ECH83 or other strange positive control grid options (Thyratron?).I'll make up some resistors on patch cords for the magic eyes that need them if the integral amplifier is driving deflection electrode. Only some have the deflection electrode(s) separate.

I was going to add a 50uA meter and a 300V via 4M7 Ohms from a PSU taken from €5 recyclable Kodak Flash camera. I remove the 300uF replacing it with 1uF foil and the flash tube. I use one as capacitor leakage tester with 2 x 1M resistors to one terminal and neon with capacitor to the other test terminal. With a suitable cap the neon flash’s about 0.5Hz for 100M leakage and about 5Hz for 10M Leakage, 1M leakage looks solidly on. But presumably with suitable switches the uTracer could test for H - K leakage, g2 - g1,  g1 - k , g3 - a and g2 - a etc. with heater on and off, using its own PSU. Or whatever tests the AVO had, I forget. 

Thanks for sending me the wonderful kit! Michael  Watterson.

ps: a magic eye being tested on Michael’s uTracer can be seen on YouTube

pps: follow Michael’s progress on the Valve Radios & Television forum.

12th May 2013, Fabio Valente sent a few very nice pictures of his uTracer, and a warning!

I recently completed boxing of this very nice device. Building has been a pleasure, manual is superbly written. Another Italian diyer who bought this kit defines it "a masterpiece of clarity". Parts and PBC are of high quality. It worked perfectly since first turn on and very precisely, only very minor calibrations were required. Measurements are really repeatable. Thank you Ronald for getting it available in kit form allowing price to be acceptable to diyers.

Some considerations I find useful for other people interested in it.

I've really been close buying a old tube tester. These are all very old and sold for too much money. Often with problems, furthermore, you can bet on them, they will need a complete overhaul and calibration. Then, easier said than done, you'd have a instrument that will measure something in a single working point (that you don't know). Really little, little information compared to what you can get with a curve tracer, if you want it, otherwise you can always measure in a single point: one indicated in datasheets. Not a unknown one! Last point, for people buying expensive used tubes, on the bay, but not only. You CAN'T imagine what is sold and at which prices nowadays to, mainly, audiophiles! Sellers, those in bad faith especially, know people can't measure what they buy and they make a profit from that! They even write FALSE measurements values.... being almost sure to get a positive feedback at the end! Sooooooooo, before spending something like 200 Euro for those special 12AX7 Telefunkens think VERY seriously about the possibility to get this tracer earlier!

29th April 2013, Jurgen Timpert sent a very nice review of the uTracer his son built!

Building the u-tracer kit was pretty easy. The instructions were one of a kind, providing step-by-step component placement instructions and clear pictures of the board after each completed block. Building the kit block-by-block and testing each block before proceeding is a much more sensible way to build something like this than the usual order of fixing resistors first, and then the larger components. Kit manufacturers could learn something from this! I know from experience how much work it is to compose component kits and to distribute them, the Dekker family did an excellent job here. All resistor values have their own baggie for example, and in general, all components were easy to find.

After trial connecting a tube to the board, the first traces were made. Provided the grid stoppers were there, a 6N1P was easily tested. The software had a few hiccups working on a Dutch Windows system (both W7 and XP), and the only thing that would work was to set the country settings to US English and then start with a fresh calibration file. Once this was sorted out, the software worked on both test systems.

I have the habit of cramming my projects into enclosures that are as compact as I can get away with. This project is no exception, the enclosure is a TEKO CP/4.20. Fitting the board in it is no problem, as there is ample space. But the top lid, when populated with nine sockets and a patch area, is nothing too big. I have used the proposed AVO wiring scheme with loops and strategically placed beads, 40 beads in total for nine sockets. Where the loops are connected to the connection bushes (they are included in the loops just like the socket pins), two beads are used, one at each side of the bush. This is to make sure that the patch cables cannot act as an antenna and cause oscillation. The sockets most prone to oscillation (octal, noval and magnoval) are those that are likely to see the highest transconductance tubes. They are on "front row" close to the connection bushes. Especially the UX4, UX5 and P8 sockets are unlikely to ever receive a particularly "hot item", and thus are located further away from the bushes. The scheme works: I can test an E810F at high current without any oscillation occurring. The beads used are Kitagawa RI-4-10-2 with a nominal impedance of 50 Ohms. In the photo, a GE 7581A is being tested.

All in all I am very happy with the result, I am sure that the u-tracer will see good use with mu future tube based projects. Thanks for providing the tube community with such a nice and useful instrument!

Jurgen Timpert

20th April 2013, Marcin Adamski from Norway uses his uTracer to test ancient his radio tubes:

Dear Ronald,

I would like to report another successful build of uTracer kit. Everything worked exactly as it was supposed to. It is a great kit and a great tool for me for testing my ancient valves. Please see attached pictures of my uTracer. The tube being measured was Super Airline GX-201A. Everything works as promised. Thanks a lot for this wonderful tool.

Best regards,

18th April 2013, Henning Hoeberlin reported his uTracer working:

Hi, µTracer Team ( I call it Team after i have seen the whole Family working on this :-) )

  I have finished assembling the Kit, all steps were working as expected, i was able to find one small mistake that I made myself, thanks to the "assemble and test in steps"  idea, which I just a brilliant idea! I have tested the first tubes, and I am impressed by the many functions this device has. I have no photos for You yet, as I still need to make the "housing". I already have the Idea, and will place a dedicated Laptop on top of the Housing, which is only 4 - 5 cm in height, and there will be the Tube socket and Cabeling Area on the left side of the Laptop, while the µTracer board, the µTracer Power Supply, and also the Laptop Power supply are located inside the housing. The Laptop I use is a very old Dell Latitude CPx, with Pentium 3 Processor, with Win XP, and only 256kB of  Memory!

11th April 2013, Achim Korn sent a photo of his fine uTracer case:

Photo #1 shows the the top of the uTracer. The connectors 1 to 9 are wired to the 25-pin connector. Only every third pin is used on this connector to provide a good isolation between the pins. The connectors H~ / H~ provide the AC voltage for the tube filament and the connectors H+ / H- provide the DC voltage for the tube filament. The DC voltage is adjustable (switch and pot).  

Photos #2 and #3 showing very simple tube adapters.

  Photo #4 shows the bottom side, where you can see two power transformers and three homemade boards. One transformer is used for the 19 volt DC supply and the other transformer is used for the DC supply (filament) of directly heated tubes (1.2 to 6.3 volts). The homemade boards are made for the voltage regulation and filter units.  

I hope my version of the uTracer is not to bad. I wanted to build this unit with parts which I had at home. In the meantime I made a lot of measurements and I did not find any problems.  

Thanks again for providing such a good tool.

  7th April 2013, Francois Bergeret (F6HQZ) sent a photo of his beautiful transparent uTracer case:

Francois uses a separate tube socket adapter for every other tube socket. The wires have isolated 2 mm banana plugs for safety and to make the device “idiot proof.”

1st April 2013, Heinrich Stummer sent some photo’s of his finished uTracer case:

Hello Mr. Dekker,
Now my utracer case assembly  is ready.
All the valve holders are located in separate boxes. (avo style wiring inside)
This device works great and is very usable . I took some traces of old tubes laying around in my shack.
Thank you for the excellent kit and construction manual.

25th March 2013, After a long journey through Russia, Alex’s uTracer kit reached him after which is was finished in no-time!

17th March 2013, Francois Bergeret’s (France) uTracer is up and running:

  Thank you to our friend Ronald and his family to have offer us the possibility to build the kit of his superb µ-Tracer V3. No issue during the building and the tests, all was running immediatly as expected. It was a great pleasure to play with it and discover what measurements are possible. I can recommend it to all guys who search such a modern tube tester : it works well and have no comparison against any old, often too high cost and not running unit sold through certain commerce WEB sites. Francois Bergeret F6HQZ, French radioamateur, playing with guitar tube preamplifiers

16th March 2013, Jerry from the US finished his uTracer:

  I have finished the project and it works great!
Attached are some photos for you.
You may publish them as you wish.
I was testing a 6AU6 in the photos.  


16th March 2013, Jim MacWilliams from the US sent a few pictures:

Here are a couple of photo shots from my completed uTracer. Assembly was straight forward with no real problems and in keeping with Ronald's recommendations. Not a work of real beauty, but it's the function that counts. Eventually I'll mount a LED on the front panel to indicate HV on. I also left space for more tube sockets/valve bases, but I may just make adapters for other sockets that plug into one of the sockets that already exist.

The instructions were very well written and easy to follow. Now to spend time gaining experience.

13th March 2013, Kevin Kennedy (US) took the time to write an extensive review:

I stumbled upon u-tracer quite by accident on a thread on diyAudio on day, and have been thinking for years that it would be useful to have some sort of curve tracer for tubes. I contemplated designing my own, but lack the programming skills to integrate it with modern computer based hardware. I was literally thrilled when I discovered Ronald's website to see a very well evolved design described on his site. It didn't take long for me to decide to purchase a kit, and it arrived very promptly and well packed. I had a choice of three different computers to install and test the software, my preferred system worked fine. (I do plan to install GUI on my laptop and import the calibration file for portable use.)

Unpacking the kit it was clear immediately that a lot of care and thought went into this kit, in the event of potential confusion most parts are clearly labelled and packed in a fully logical manner. The construction manual is detailed, clearly written, and of the same order of quality as you would find in classic ear Heathkit manuals. All steps are clearly detailed, and as you build up the board you test and calibrate each circuit in turn. A good quality DVM and preferably a lab supply furnishing 19V with an adjustable current limit is all that is required to build and test the unit.

The PCB is high quality and went together without a hitch. I did note that the hole spacings for resistors in particular are a bit tight, but the resistors fit fine as long as you follow Ronald's guidance and bend them at the body. The only SMD components come pre-soldered, and the balance of the parts are through hole.. This was a very nostalgic assembly experience for me as I almost exclusively work with SMD components in my day job. Parts are all high quality and sourced from reputable vendors.

Each step along the way was completed without drama, everything just worked as expected. The calibration procedure at the end of each of the later construction stages is simple to perform and the outcome obvious. I did add a 3A reverse supply protection diode across the supply terminals early on as I could just see myself hooking up the supply backwards..

Support is excellent, any question or suggestion garnered an immediate response from Ronald. :)

If you can solder, follow well written instructions, and follow minimal ESD precautions during the build you should have no trouble putting this together and getting a working unit at the end of the process.

Testing my first tube was a lot of fun, and provided immediately useful results.  Having fully tested and vetted the project I installed it within a case made by Landfall Systems (TX) which I had to machine. I had a not so minor mishap with the milling machine which marred the top plate unfortunately, but JB weld provided an adequate fix. I followed the AVO approach outlined in the manual for the sockets and installed six sockets to allow me to test most of the types I use or could conceivably use in the future. (UX4, UY5, Loktal, Octal, 7 and 9 pin miniature.)

The GUI will derive tube transconductance for various operating points which is useful. I find an excuse to curve trace a tube almost everyday. The tracer is extremely simple to use and answers profound questions about the suitability of a tube for any given purpose. One thing that is clear is that all of my preferred types (mostly triodes) tend to offer rather good linearity. I'm still exploring the various features the u-tracer offers, but have to say this is probably one of the most useful devices I have acquired in years. I unconditionally recommend it to anyone interested in a capable tube tracer.

Kevin Kennedy

12th March 2013, Heinrich Stummer finished the build of his uTracer :

Dear Mr. Dekker,

because I had some extra time this week, I was able to complete the utracer kit now.
The building was much easier than I expected.
Build and test, all works smooth.

4th March 2013, Richard Zajkowski (France) sent a few pictures of his finished uTracer:

When Ronald mentions on his blog that someone sent his uTracer to him because of some more severe problems, well that was me. I still don't know what caused my problems but I think that Murphy was sitting on my shoulder all the way during the construction and the tests. Anyway, sending back my uTracer for checkup and repair made Ronald discover a small problem with the IRF840's, see his blog (22. The Final Problem). In the mean time the uTracer is functioning well and has already served to test a number of tubes for my next Tube Amplifier. As you can see from the pictures, mine has been put in a service case and since I still have a flat screen and a mini-ITX pc board lying around, those will be also integrated into the case so that the uTracer becomes a "stand-alone" instrument without the need for an external computer. To finish, I congratulate Ronald for the excellent kit and construction manual and thank him for all the help I received during the construction phase.

3rd March 2013, Jerome Kahn wrote:


I have just completed assembly of your very fine kit.

My compliments on a very well written assembly manual and the high quality of components used. The entire assembly process was trouble free and enjoyable. I especially enjoyed your hints and tips section.

I am going to use your banana-jack technique to connect the tube sockets.

You have done an excellent job in every respect in product design and the extremely difficult job of writing an assembly manual, I am extremely impressed. I look forward to getting the cabinetry and external wiring done so I may enjoy this little Gem.


25th Februari 2013, Have a look at the magnificent realization of the uTracer by Ilpo Leppänen (Finland).

Ilpo is a radio amateur from Finland who takes is hobby very seriously as you can see on his site!. The contruction of the uTracer was without difficulties: “This kit was well laid out and everything worked as it should.” A series of beautiful pictures showing the step-by-step construction can be seen here.

24th Februari 2013, Rüdiger Waltz uses his uTracer to test his own Homemade tubes !!

One of the most special people who have built the uTracer3 is Rüdiger Waltz. Rüdiger has his own workshop where he makes replicas of antique radio tubes since 1983. He has made a document which summarizes his experiences (Click here to download). It is absolutely fascinating reading, and a tremendous achievement. The photos below show the uTracer testing one of his replica tubes. In the left graph below the photos an original RE11 tube is tested, and compared with one of his replicas (right graph).

Rüdiger even uses the uTracer to measure exotic valves like Loewe multiple valves!

19th Februari 2013, Klaus Ortwein from Cologne from Germany send a few pictures of his beautiful implementation of the uTracer

14th Februari 2013, Ari Huju send a few pictures of his implementation of the uTracer:

13th Februari 2013, James Hill send an update:

Sorry for not giving any feedback so far. I completed my uTracer last year and have been using it "naked" but am now working on boxing it up. I wanted to wait for the finished article before emailing you. I am fitting the board into a Hammond case with an inbuilt smpsu. I am awaiting the front  panel from Schafer but the mock up is shown in the photo. I will email again on completion. 

The kit build went absolutely fine. Your instructions were excellent and made the process a pleasure. Everything worked first time without issue! You are more than welcome to post the pictures, I will send some more once the front panel arrives and construction is complete.  The design seems very flexible and I am excited by the prospect of future expansion of the units feature set. Thanks for all your hard work in developing the tester and congratulations on the end result.  I have attached a picture of the tester in action with a kt66. 

Thanks for a fantastic product! 

13th Februari 2013, Bill van Dijk (Canada) send an update:

I just made a couple of pictures of the finished project I wanted to send. The uTracer has found its home in a recycled APC UPS housing. Although working with a steel case is a wee bit more annoying It is working flawless so far (although of course I do not use it daily). I'll attach a couple:

In case you wonder why there is a terminal 12 all by its lonesome self, well that's because I can't count! After I finished drilling all the holes I realized the white socket has 12, not 11 pins! That socket btw, is for a number of TV tubes, such as the 33GY7A (horizontal output driver, which I will have to feed with an external filament power supply).  

I had a look at the V3 wish list and I suppose some of the items will be V4 items? It seems to me that not all can be implemented in the existing V3 units? Anyway, you mentioned an impending software upgrade, I'm looking forward to that. One wish item I have relates to the calibration data. Is it possible to store the calibration data in the PIC's EEPROM? That way the GUI could retrieve it from the device at startup, and would be safer than the PC (I fairly regularly reformat my work PC, plus I actually have 3 PC I work with). My next suggestion may well be excessive, I have no idea about the complexity of the GUI, but here it goes none the less. I think it would be nice if I could add information to the graph after it is created, such as a load line for instance. It would help determining bias points etc. much easier. But printing, pencil and ruler work also.  

Thanks again very much for a great project, I'll keep this around for a long time!

12th Februari 2013, Nick Barton from Black Magic Amplifiers wrote:

Thank you both for taking the time and care to put this kit together. I highly appreciate it.

I have attached a couple of shots of my version. The construction went very smoothly. I seemed to have quite a lot of spare resistors. I hope someone else didn't find themselves short!

25th Januari 2013, John Hayes finished his uTracer:

Just wanted to let you know I have completed my uTracer kit. Everything went very smoothly from start to finish. You did an amazing job with the design, packaging and documentation of the uTracer V3 kit. The assembly manual is amazing! I tested it on a 12AX7 tube and it worked perfectly. I'm almost finished with the final assembly into a case, and I will send you some photo's in a day or so.

8th Januari 2013, Yves Dupont shares his experiences with the uTracer:

I’d like to give you my feedback about the uTracer.
Building the kit was a breeze due to the excellent construction manual.
With the risk of repeating myself: The uTracer hardware design is outstanding.
It’s a tremendously useful tool, thanks for sharing with the DIY-community your work and your time.

Please find enclosed a picture of my case-implementation and a curve-trace of two used chinese 300B’s.
Both were working, the AVO Mk4 indicated a lower emission for one of the two.
But the uTracer shows that one is really a unusable dud and the emission for the other tube starts to nose-dive a bit on higher currents.
In short: I’m *pleased*.

1st Januari 2013, Michael Schlör from Germany finished his uTracer during the Christmas holidays, he writes:

Hi Ronald,

Thanks for the kit!

During christmas holidays I finished my uTracer without any problem. It works great. I tuned it with my homebrew analogic tube tester and the uTracer is very accurate. You see my wooden box measuring an EL84. The unoccupied side on top is provided for the respective paper with the tube base diagram. This will accelerate setting the connection cables.

His testimonial in German:
Der Zusammenbau und schrittweise Abgleich verlief  dank hervorragendem Manual problemlos. Ich entschied mich bei den Verbindungen zu den Röhrenfassungen für steckbare Kurzschlussverbinder. Die Buchsen vom µTracer habe ich ähnlich wie im Handbuch beschrieben doppelt angelegt. Die Verbindungen zwischen den Röhrenfassungen sind größtenteils mit Breitbanddrosseln ausgeführt. Anfangs hatte ich auch in beide Heizleitungen jeweils RFI Drosseln gelegt, doch stellte sich beim ersten Test mit einer EL84 heraus, dass die Heizung deutlich zu niedrig war. Die Röhre erreicht nicht ihren Ia Wert, den sie mit externer Heizung am µTracer erreichte. Der Unterschied war signifikant. Die Breitbanddrosseln reagierten offensichtlich schon deutlich bei der 19kHz gepulsten Heizspannung. Nach Entfernen der RFI Drosseln aus dem Heizkreis sind praktisch keine Messunterschiede mehr zwischen interner und externer Röhrenheizung  feststellbar. Ich benutzte den Ia Wert der EL84 mit externer Heizung und kalibrierte so mittels Usupp Schieber die interne Röhrenheizung bei meinem µTracer.

The PL802 has a very high transconductance of 40 mA/V and oscillates very easily. Michael tested the PL802 in the uTracer to see if it would oscillate. It didn’t!

31st December 2012, Nick de Smith from Kent, England, finished his uTracer on old year’s night:

Click here to view Nick’s “Thread” on the diyAudio forum

Finished building - no real problems at all. Setup was fine. Great kit. I did, however, take great care when assembling the kit - cleaning the board after each section was complete with IPA and visually inspecting each joint - I use Metcal MX500s for soldering & Lindstrom cutters to trim the board. Looks very smart - this is a well-designed & laid out board - simple to work on and well structured. Good quality components - like that! E.g. using turned-pin IC sockets and decent electrolytics - costs a bit more, but well work the extra.

31st December 2012, Joris Weijters from Holland send a few pictures of his version of the uTracer:

Joris uses an optically isolated USB to serial converter from ELF. An excellent idea! the converter is very cheap but unfortunately the site is only in German (as far as I could see).

9th December 2012, Lauri Salasmaa from Finland sent a few pictures from his version of the uTracer:

Despite the fact that Lauri is not one of the youngest radio-tube enthusiasts, he got his version of the uTracer running without too many problems! Currently Lauri is writing a report in the uTracer for a Finnish Internet Forum. Lauri uses a USB-2-TTL converter to connect his uTracer to his laptop which only has an USB port, a great idea!

7th December 2012, Pascal from Belgium made his own uTracer on Perfboard:

My uTracer works ! It isn’t a real beauty (made on perfboard), but I’m satisfied. I use decade (+ “off” position) thumbwheel to select tube pin numbers, the whole fits into a Teko P4 enclosure, there is sufficient room to add tube sockets. This “big” model of thumbwheel has a sufficient insulation. The output for K and G1 are duplicated to test duo-diodes and duo-triodes (G2 works as 2nd A.) (tested at 500V with a Megger.) The PGA are a pity to solder, but it is possible with conventional tools, adapters and desoldering braid. I add a transil on +5V. There are 2 photo’s with my first contact (in 1978!) with electronics, the fantastic EE2000 series.

1st December 2012, Kurt Schmid posted an extensive (German) review on the Radiomuseum forum (click here)

Kurt designed and made a beautiful case for his version of the uTracer:

Using a Bogey calibration tube, Kurt checked the accuracy of the uTracer. Both the anode current, as well as the transconductance were within 1.8% of the value of the reference Bogey tube! Click on the pictures for a larger version.

Bogey reference tube
Anode current measurement
Transconductance measurment

27th November 2012, Pat Hickman “Head Tubeologist” from Classic Tube Audio send a few pictures from the construction of his version of the uTracer.

November 24, 2012 Derk Reefman from the U.S.A.:

I have been facinated in tubes and tube circuits since my childhood - most likely because my grandfather had been working with the dutch "PTT" (post and telegraph and telephony), and later my dad, too. I have been the exception studying chemistry and physics... Anyway, I have a hobby in building hifi audio tube amplifiers. When it comes to building amps with distortion figures below -100 dB and bandwidths of 50 kHz (I am a super audio fan!), knowing the tube's characteristics is paramount. I have long been searching for something simple  but complete that could give me a tube characteristic that I could parametrize and load in spice (or your favourite circuit simulator). And now I have found it! Ronald's kit for a tube tester/analyzer was really easy to build, had a very good manual for testing... What can one wish more?

To anyone looking for an excellent tube analyzer: mail Ronald, and request his kit!

Derk Reefman, nov. 24, 2012

November 21, 2012 Bill van Dijk from Canada wrote:

Hello Ronald,

Please add me to the list of successful builders, I have completed my kit, and it works fantastic. No issues at all!

My complements on a great kit; it is very well designed, no short cuts anywhere. I’m not sure if everyone appreciates, or even realizes how much of your work has gone into that. You even went as far as cutting out the centers of the PIC socket, very impressive. My complements (and thanks) also to Marie-José, I have the feeling she may have done more work in the back ground than we know. I made one tiny change, I did not solder the 2 LEDS directly in the board, but inserted a 2-pin female connecter instead. I then pushed the LEDS into this connecter. The reason is that I can plug a little cable into it later so the LEDS can be mounted in the top of the case (which I have not yet found).

November 19, 2012 Robin Simmons from the UK wrote:

I've been looking for a 'valve tester' ever since starting my own company repairing and modifying electronic equipment such as guitar and hi-fi amps. The vast majority of existing equipment that I have seen so far is either totally inadequate in terms of functionality or else over priced. In fact, usually both and only available second hand when they're already worn out. Not any more! Enter the uTracer designed by Ronald Dekker. I have been following this project for some time and jumped at the opportunity to buy a kit and build my own tester. Being an Electronics Engineer by trade this held no obstacles for me but even if you're not then Ronald provides all the information you need to build a uTracer with only a few simple tools and a bit of patience.

Once in operation the uTracer does everything expected of it. Now, instead of carrying out tedious pin by pin measurements trying to identify faulty valves from good ones when an amp arrives in the shop, it is simply a matter of plugging each valve into the tester in turn and letting it do the work. Not only are shorts and open circuits immediately obvious but also transfer curves now enable me to identify low gain valves and mismatched valves easily. Even with the few bugs that are present the uTracer still works well and can only get better as Ronald irons out a few minor issues and more people get to play with the design and help develop it further. I cannot recommend this tester enough for anyone needing to test valves and get accurate real life results for a very reasonable cost.

November 18, 2012 Georg Beckmann posted a review on the uTracer on the Radiomuseum forum (click here)

The uTracer from Georg Beckmann on the test bench

November 8, 2012 Lourens Koopmans from Holland:

After receiving the uTracer3 kit from Ronald, I immediately started assembling the PCB, the build is straight forward, all steps are clearly described and all separate parts of the uTracer3 are individually tested. The testing and calibration was no issue, I only made a small mistake measuring the grid voltage referenced to ground instead of the cathode.

The software GUI is working fine but I have some issues with it:

  • Sometimes the serial communication with the uTracer3 is lost when interrupting a measurement.
  • When selecting -50.0V grid voltage this is actually 0V !
  • The window size of the GUI cannot be resized or maximized full screen but this has probably to do with the used visual basic version the GUI is written in.

I would also be nice to stop the measuring of a curve when the max. anode, screen current of a manual defined diagram is reached, this way you could trace curves with low voltage or 0V grid voltages without going into overcurrent protection.

But the uTracer3 is very usable at this moment, I took some traces of random tubes laying around, click here for the measured traces and the snapshots of the datasheets. The uTracer3 is very accurate!!

At this moment I am building an enclosure for the uTracer3, I will use replaceable dual tube sockets similar as the Tektronix 570 uses. This way it is possible to match two triodes.

29 October 2012, Roger from Germany:

18 September 2012, Kurt Schmid posted an extensive (German) review on the Radiomuseum forum (click here)

11 September 2012, Roger from Germany wrote:

Being fascinated by tube technology, I had cheaply acquired a few tube-radios some years ago. The purpose was to build up a small collection representative of German tube-radios of the 1950s..1960s era. What was missing was a universal tube tester so that I could start restoration. Everything I found on the web or in books concerning tube-testers was either too simple, not universal enough or too expensive.

That was until I found the µTracer from Ronald Dekker on his website. After reading the first paragraphs of his weblog about the development of the µTracer V3 I was totally thrilled about this ingenious project and its possibilities. Wouldn't it be great to measure all kind of textbook curves with nothing more than a laptop, a small switch-mode power supply and a circuit board for the measurement electronics not larger than the „Euro-format“ (100x160mm)? No heavy power transformers and power electronics, no manual plotting of the measurements on graph paper, no manual calculations of transconductance µ or other tube-parameters... But instead everything done automatically by the laptop/PC connected to a small box. Doesn't it sound like magic? And nearly no limitations concerning filament voltage and current and anode and screen voltage and current and all that at a price of less than a few NOS tubes.

You can even build a portable curve-tracer with a laptop and a rechargeable battery-pack instead of the switch-mode power supply. That way you could test tubes of unknown quality on the spot e.g. at flea markets, ham conventions etc. All that totally exceeded my expectations for a suitable, affordable and easy-to-build tube-tester by at least an order of magnitude.

So I immediately decided to start building my copy of the µTracer V3 because I couldn't wait until Ronald would release a kit. After finding some more readily available replacements for a few of the rarer components, I ordered all the necessary parts and immediately started building the µTracer V3. Ronald gave me constant feedback which was invaluable in sorting out some wiring errors of mine. The most important advice from Ronald was to build and test the µTracer V3 step-by-step. Building (and understanding) the circuit went quite smoothly by carefully reading and constantly consulting a printout of the development weblog. That gave me more satisfaction and a deeper appreciation of all the ideas that went into the µTracer than by simply soldering a kit together. I tried to copy the layout of the components of Ronalds prototype on perfboard as good as possible but in the I won't win a beauty price with my version :-) Where I deviated from Ronald’s design was in the selection of a case because I wanted a very universal µTracer V3 for all possible tube-sockets to do justice to the universality of the µTracer V3. So I shamelessly copied the design of the interchangeable test-boxes of Helmut Weigls „RoeTest“ and thus kind of merging ideas from the two best designs for a tube curve-tracer that I know about.

With all parts working and finally connecting the µTracer with a serial cable to my PC it was absolute magic when the first measurement curves of a simple resistor appeared on the screen. They were absolute textbook-like straight lines and looked like copies of Ronald’s own curves.

I cannot stress enough how much fun it is to work with this device. The GUI that Ronald has created is absolutely amazing and it really makes so much fun to test a tube with all thinkable parameter combinations. I estimate the µTracer V3 to have an overall absolute accuracy in the 2..3% percent range if you use high-quality components and do the calibration as proposed in the manual.

There are some very minor (non-critical) quirks I noticed and a few suggestions for further improvement that can easily be remedied or implemented in a future GUI and/or firmware update.

  • It would be nice to have a button in the GUI for saving and loading the measurement-settings with a descriptive name. Thus you could easily load the necessary settings for repeated measurements.
  • The effective filament-voltage at the tube-under-test can be slightly lower than the calculated one due to DC-resistances (inductor L2, wire-resistances etc.). That is because the filament-voltage is the only one in the µTracer V3 that doesn't have a feedback to the microcontroller and is just calculated from the (unloaded) power supply voltage and the necessary duty-cycle for the switching transistor T3. In extreme cases with heavy filament currents in the ampere-range the filament voltage at the tube could be up to 10% lower than calculated. As Ronald himself shows in his weblog in figure 18.7 this can lead to a significant deviation from the „textbook“ curves of a tube. This could easily be compensated by using one of the free entries in the calibration section of the GUI.
  • Grid voltage can be input only up to -49.xx V and not up to -50V.
  • When you are in the highest current-sensitivity in the diagram (0,1mA full scale), the cursor displays „0“ in the y-value, when you select a measurement point with a low current.
  • Sometimes the x-axis ticking changes from „round“ to uneven values during measurement when „Voltage correction“ is switched on.
  • The maximum selectable anode or screen-voltage should be increased to 350 V. When all hardware components in the high-voltage sections are suited for 350 V or more, there could be a (hidden) switch in the GUI to increase the maximum selectable anode or screen-voltage to 350V.

Roger’s version of the uTracer 3

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