Out of frustration at the performance of my many tube testers for testing type 12AX7 and a few other high gain tubes I decided that a curve tracer was most appropriate for testing and matching some tubes. In addition to the fact that tube testers only report at a single operating point (insufficient for matching), the test grid signal tends to slam the 12AX7 tube against the limits of operation. Not wanting to pay a high price for a vintage and large Tektronix curve tracer or a fully assembled modern unit, I opted to purchase a uTracer 3+ kit. The kit consists of filament, bias, screen, and plate power supplies plus instrumentation to monitor operating parameters all located on a single circuit board. Instructions for assembly are very clear and comprehensive reminding me of my Heathkit experiences. Not included in the kit are a power source (19-volt +/- brick type computer power supply), computer interface cord, computer, and tube sockets most of which I had available. Assembly of the circuit board was quick and gratifying, a welcome distraction from the aftermath of the Carr Fire that I was concurrently dealing with. Since completion and initial testing of the curve tracer, I have been busy building a cabinet to contain the circuit board, brick power supply, patch panel, and tube sockets. Here is the result, less than 11.5-inches wide, 6-inches front to back, and 5.5-inches tall.









The tube being tested is a 12AX7. Both halves are being tested simultaneously. The plot indicates that the tube is operating like a new tube (based on comparison with manufacturers plots) and that both halves of the tube are reasonably well matched. Except for the wood ends, the cabinet is 14 gauge steel plate left over from a Scott chassis project. More information on the uTracer 3+ can be found at the link below.

https://www.dos4ever.com/uTracer3/uTracer3_pag0.html

Norman

That's cool! My buddy built one of those few years back. Really tells a lot about the tube being tested!


Todd

Nicely done Norman!

9 pin serial out? Do you know what operating system is will work on? win95 up?

Very nice!

I always wondered what to do with this old metal Makita case

Will your tester check a 300B?

Thank you!



I clicked on the link and read a bit about it. Windows XP and Windows 7 is noted.

Not at this time but with the modification described at the link below it will.

https://www.dos4ever.com/uTracerNoteboo ... html#grid4

Norman

Thank you Norman.

Did you notice that Ronald Dekker placed a poll for visitors to vote for an extended grid bias circuit kit, or possibly, for a new version of the UTracer with the extended voltages? So, everybody get over there and vote

His schematic was dated just about a week ago too.

A great price for the kit and for the work he put into it.

It will test most tubes including the 300B, but for directly heated triodes it requires an external power supply and the cathode needs to be connected between a set of resistors to act as a voltage divider so it sees the midpoint between 5V filament voltage. I set this up in my unit years ago, major limitation was the limited bias voltage range. I set mine up to to use thumb wheels and use the AVO test data same as my CT160 tube testers. Gives surprisingly accurate readings. I use a RS232 to USB internal adapter and also a wireless Bluetooth connection, the software runs on any version of windows. I have updated the board, to the 3+, but at this point a new board/updated design is preferable. Credit to the designer to provide so much for so little.

This is wonderful!
I've been thinking of designing and building my own tube tester (with parts and ideas from other testers) but this may be the better way to go

But, I have too many projects in the queue to begin with. (overwhelmed)

-Steve

I hope to buy one relatively soon, with the idea I will build it over the winter. I have bought an emission tube tester with the traditional lever switches in a wooden cabinet specifically for this purpose.

A good friend who owns one states he values it highly. Good enough testimonial for me.
John S.

I built a uTracer about a year ago. So it sits, fully tested and ready to go, in the job tray waiting for me to get time to build it into a box with sockets, wires, pins, and stuff. . I keep getting sidetracked with 100 other projects.

.....if only I could find someone to help me with the 100 other projects.....

I'll help you if you'll help me.
Wait, we need to clone ourselves...

-Steve

I built one 3 yrs ago and have been very happy with it.I do guitar amp repair and use it for a limited variety of tubes so building the tube socket selection was simple,no switches,just 6 sockets to handle the limited number of tubes used by guitar amps.

Nice job! I built one last Christmas vacation and have used it very little due to the lack of a housing. The kit and the documentation are just amazing, a work of art almost. I am currently in the process of building it into my Heathkit TC-2. I went back and forth on doing it this way or in an independent housing. There are pros and cons. But all those pre-wired sockets in the TC-2 were too much to resist although there will still be some wiring left to do. For one thing I am adding a compactron socket in the spare hole on the TC-2. I've got all the mechanical bits mounted on the front panel so now it is a matter of wiring all that up and mounting the uTracer and its power supply into the tube tester case.

I like having an emission tester to sort the duds out from the tubes worth further investigation and to do a shorts test. I would really rather not let the uTracer do that! The TC-2 also supplies an independent heater supply when you want/need that.

I have been intrigued about this kit. I read about it a few times and visited the webpage. The one thing I could not find info about does this kit allow for some form of gas test and quality/life test? I doubt it given if it did the webpage would obviously state so in the very beginning of all the info. There is a lot. But I have to ask for the sake of asking.

Regards

Gas and grid leakage will show up as excessive conductance, plate current curves steeper than a new tube. A decent idea of remaining life can be inferred from how flat the plate current curves have become from a new tube. I test all tubes for shorts and heater-cathode leakage on a Hickok Cardmatic tube tester first.

Norman

The uTracer should not be thought of as a tube tester. I have no doubt that it can do everything a tube tester can but I certainly would not hook mine up to a tube to test it for shorts, for example! The uTracer is really an engineering tool and while it can be very good for certain kinds of work that non-engineers want to do I have to wonder how many here have a use for it. It can take tons of data but if the software it comes with does not extract the information that you want from that data you will need to figure out how to do that on your own. Gas testing and life testing are done on a tube tester with specific circuits. If you were to sit down and figure out how those circuits do what they do then you should be able to take uTracer data files and extract the same information from them. I would suppose that if you wanted to make a career out of it you could even write a program that would take uTracer data and give you the same results that your favorite Hickok or Jackson or ... tube tester would give you. The software it comes with is geared more towards duplicating the curves and specifications that you would typically find in tube datasheets. In theory it can do almost anything, one user has written a program that helps you extract tube models for use in Spice circuit simulations. So, I think you could use it to make a modern digital equivalent of any classic tube tester but some assembly would be required!!

I don't believe that enough information can be extracted from the operating curves (or data that generates them) of the uTracer, or any other curve tracer, to provide information on gas or life testing.

Life testing, in a tube tester, usually involves reducing the filament VOLTAGE (edited) and seeing if, and how much, emission drops. To do this with the uTracer, even assuming it could be done, you'd have to know what is "normal" for any given tube as far as its reduction in emission-translated-to-operating-curves.

As for gas testing, that's an analog test of grid current that the tube may be drawing. That data might be contained within the uTracer data, but since the uTracer is a pulsed test and not a strictly analog test like the Tektronix of old, I'm not certain it would work either.

I'd drop an Email to Mr Deckler, the designer and marketer of the uTracer. He would most likely know without even having to think much about it

http://www.dosforever.com is their website

Life tests just compares Gm/plate current at specified heater voltage vs. a 10% heater voltage reduction. If the Gm doesn't drop then it is still considered acceptable, the uTracer can do this and it is no different than other tube testers. There is no specified definition that I am aware or specific measurement operating point. As far as grid current, I have a switch which adds either a 100K or 250K grid resistor, if there is gas the plate cures will be higher, if no gas they are the same. This also was confirmed on my Hickok 580A. The uTracer will not test for shorts nor give you leakage between the elements.

I still use conventional tube testers, but the uTracer allows one to compare operating characteristics that have been published and works well for most lower power tubes. The newer version will potentially measure grid current, the goal is to be able to run operating curves up to 1000V and 1A, as well as positive and negative grid bias. Will see where that goes.

Nice test for gas on the uTracer mksj.... makes me almost want to finish my uTracer. The board has been done, and waiting for a cabinet and switches, for almost a year and a half now.