uTracer (Micro Curve Tracer)

[Reeltarded]

By Fischer-Price..

[martin manning]

Exactly...all you do is match the colors. Recommended for pre-K!

[martin manning]

All done! I've also installed a Windows 8 OS on my MacBook using Apple's Boot Camp, so the uTracer software can now run there.

By popular request, R Dekker has just updated the GUI software with a "quick test" option to quickly get key parameters for a user-specified test point.

Playing with the quick test got the results shown below for some 6V6's I had laying around. Some interesting points are:

The effects of use in the JJ's: Ia and Gm are low, Ra is high. Of course it would have been nice to test the same set of tubes before and after use, but this result is probably ok for general trends.

The EH's were tested and matched for Ia and Gm by the seller, but the Gm number doesn't agree too closely with the uTracer result. A sticker lists Ia and Gm at "round" values of 49/3600 on both boxes. This could just mean that a different test point was used. Overall, the EH tubes are a bit closer to the vintage spec point than the JJ's, but both brands exhibit significantly higher screen current. Again, I don't know if the microphony in article 2 (and there is also an audible rattle) and it's lower readings are related, but that could be.

[Reeltarded]

That is very cool, Martin. You should move down here.

[vibratoking]

That's a tidy build, Martin. Nice job decorating. You can decorate my house anytime. I want one, but I'm afraid it will confirm that none of my tubes are truly matched, which will send me on an expensive hunt for matched tubes, which I will never find, and I will realize that everyone I buy tubes from doesn't know what they are doing, and then my faith in the competence and/or honesty of man will be shaken. It all sounds like a downward spiral...until I start making my own tubes. Yeah, right. So can I just send my tubes to you? You could test them, categorize them, and clean them too. That thing cleans them too, right? I know you have nothing better to do now that you're done with your build.

[Reeltarded]

haha yeah me too

[Structo]

Too cool for school!

Nice job on the construction Martin.

Totally pro.

[gktamps]

Very tidy, Martin!
Are the ferrite tubes needed because wires are so cramped?
Cheers,
Greg

[martin manning]

Thanks for all the compliments!

VK, you're looking at it all wrong... This thing is going to prove that it doesn't matter if they aren't matched exactly, and I will be able to warn tube sellers that I can check up on their claims, so they'd better not mess with me... But seriously, it will be nice to be able to select a matched dual triode for a PI, and to know which tubes I can toss without remorse.

It is truly an amazing tool, and not much bigger than a pedal. Funny when you realize that it is using two computers to run one vacuum tube...

Greg, the ferrites are there to prevent oscillations. I probably went a little overboard putting one on each socket pin.

[gktamps]

Thanks, Martin. I had truncated my question, which indeed was about oscillations due to close proximity of wires, crossing, etc. I've seen this done on some other test equipment in the past, so maybe you didn't go overboard at all...

[David Root]

Verrrry interestink! as they used to say on Rowan & Martin's Laugh In. (Yes I really am that old).

I really like the idea of being able to test pentodes as I have dreamed up some applications for the old (and cheap!) combo pentode/triode TV tubes like 6AU8, 6GH8, 6CM8. You can get these things NOS NIB for $5 or so. And I would like to be able to test 5879s and other signal pentodes too.

The 300V anode limit is a tad low. Not really for those TV tubes but for power tubes. But I have a MaxiMatcher for those, so maybe I should take the plunge!

Martin, you have done us all a great service with your work on this. Thank you! Your package design looks great.

I would like to add a fourth socket for 2A3 as I have a parallel 2A3 audio monoblock planned (actually two of 'em), but I'd have to build a separate 2.5V PS for that to work.

[martin manning]

The 300V anode limit is a tad low.

When you consider that vintage testers often didn't reach half of that voltage it is no big deal. Getting data out in the middle of the characteristic where the grid curves have straightened out is going to tell you virtually everything you need to know, IMO.

I would like to add a fourth socket for 2A3 as I have a parallel 2A3 audio monoblock planned (actually two of 'em), but I'd have to build a separate 2.5V PS for that to work.

An external filament supply is easy to plug in, and a small DC bench supply would do nicely for that. Re the older and odd-ball socket types, I decided that if I ever run into the need, I'll make up an adapter from an octal base, and bought a few of those to keep handy. The only thing I kind of dismissed is 12-pin compactrons, but the banana jacks for the six uTracer terminals are right there, so anything can be hooked up, really.

[alvarezh]

Nice job Martin on your Mil spec construction!

Thanks one more time for sharing your always valuable knowledge and information!

Cheers!

[martin manning]

Thanks Horacio, and you and David are most welcome; bet yer bippys!

[vibratoking]

So I'm thinking more about this cool project Martin. Damn you! If you don't mind me asking, how much do you have in it?