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Tube Testers?

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oemcar

oemcar

Member
Joined 2020
#1
Recently acquired free box of tubes(pic)- Have another box full from young age tearing down old TV chasses...(plural??)
Want capability to eval before developing circuit for any of them, so think tester is wise 'maturing' hobby investment. Found article in link below informative:

https://www.radiolaguy.com/info/Mutual-Emission.htm

Decided on mutual conductance design, as I like the idea of introducing varying signal to the grid(s) instead of static voltage tests (emission)- if I understand it correctly ;<)
Also wanted capability to test later design (ie 60's) tubes and compactrons. So despite dizzying array of different makes and models- the Hickok 799 seemed to fit the venue. Also of interest the Weston 798-5B. Requirements moving forward were availability of good calibration and operations doc's, and houses for service if needed. The Hickok filled all of these, imo.

Would like to hear from those who have used these examples , and perhaps other rec's..
Thx,
Jim
ps. ordered this info to help w/ determining if the 799 has what I'm looking for
https://www.ebay.com/itm/122241588309
 

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#6
Interesting idea-
Locating workable laptop w/ RS232 port may be the biggest challenge-lol. I've used RS232 to USB adapters for other projects- they seem to be a bit quirky. This was somewhat addressed in the FAQ's. Price is reasonable- approx $220 US for the uTracer 3+. I like that they increased B+ to 400v in the + model.

Developing curves is first part of test, comparing those to Industry standards for each tube to establish 'pass-strong or fail-weak' is the goal.
Thanks jan,
Jim
 
#9
oemcar said:
I see the logic of your idea, but I do not have programmable PS
Click to expand...
If uou only want to test the tubes in your collection you don't need no programming. Just manually set the operating conditions and see what you get. For example, set anode voltage and grid voltage and then read the anode current.

Getting curves in an automated way is a different story and requires programmable PSUs.
 
#12
oemcar said:
Locating workable laptop w/ RS232 port may be the biggest challenge-lol.
Click to expand...
The Panasonic Toughbook series still has RS-232 serial ports avialble as an option. They are a bit pricey new, but you may find a good deal used.
I have one at work for legacy PLC software, and recently we looked into getting another one. I was suprised to find RS-232 was still available.
 
#13
oemcar said:
Jon, I ordered the manual to get a listing of the tubes the 799 could test. Is there an open source for this type of list for various testers?
Jim
Click to expand...
I would have a session on the gargler (Google) to search for specific model of testers and then they usually list settings for the valves.
I use an AVO 160. It came with a large binder with thousands of valve types and equivalents plus, (long before the computer and digital) all controls are manual switches and dials so it will suit any type and size of valve, whether 1.2volt filaments up to 160volt heaters. The valve bases that the older units come with as standard, fit all types of base.

I did take a look at the model you are looking at but they are limited to more modern valves. I test pre war valves with odd bases and odd parrameters so it would be no use to me.

To test a valve all you need is a heater supply, anode and screen grid supply plus a variable bias voltage with a current meter between the cathode and the negative of the HT voltage for the anode/screen. I made one years ago and it was very successful.
Set the heater voltage to the required amount, nominally 6.3v AC.
Turn the bias control to maximum negative voltage and power up the vale. Wait a minute and adjust the bias to get the valve to start conducting and note the voltage and current.
Switch off and plug abother valve of the same type in.
Repeat.
If the current and bias voltage are close to the last valve, it is what we call matched and suitable as a matched pair for output stages (if EL84/34/6L6 etc). Most valves are wildley different in their cut off point due to the construction differences.
When you get the feel for how the valves are reacting you can adjust the bias into saturation and monitor the maximum current with that you can easily workout the maximum dissipation to see how much life is left in them.
No valve teaster checks for noise!
 
#14
A tube tester is something I always thought would be really handy to have, but I only have very very intermittent use for one. So I couldn't justify the price of buying one in Europe. A few weeks ago I came across the video linked below, and did a bit of rooting around. In the space of an hour or two, I had an octal and noval board knocked together and could use them with a HV supply I have that has a negative bias voltage. Its handy to have that all in one box, but you could do it with a few. The test sheets are out there on the web for lots and lots of valves.


 
#16
I see many replies focus on testing and graphing 'semiconductor' properties of any given tube on the cheap... thx for replies.
Sure, curves are good for designing circuits and determining component values... and the ultimate arbiter for matching tubes-imo, if processor controlled.

But I'm looking for something bit more than just a curve or curves-
Rather, dynamic eval's of tubes when compared to Industry standard parameters - ergo rendering pass/ not pass results that can be documented. It's my supposition that gauge test values of same tube models using mutual conductance method (better than single point emission-imo) will give good idea of matching tubes. Perhaps thats oversimplification... anyone else tried this procedure to match tubes??

Ultimately-
I've many tubes that I can't see use for in my future. So plan is to post these cast a ways on ebay to someone who can use 'em. Revenue generated will offset investment cost of Hickok 799. IMO- what will give these ebay sales credence is testing results from industry established machine.

Soo maybe I shud've layed all this out to begin with :</
Jim
 
#17
If your intention is to sell the tubes in that box, I don't think it is likely that the money you receive from those tubes will cover the expense of a tester/tracer. If you put that box of tubes on eBay in an auction, it's not likely that they will sell for more than $100, IMHO, coz I don't see popular tubes in there. I have seen similar box of not so popular tubes ending up with merely $20-60 often in eBay auctions.

But if you are an antique radio enthusiast and want to test tubes when fixing radios or you want to develop some circuit, that's a totally different story.

Hickok 799 is not a very good model, IMHO. If you want to buy a Hickok testers, go for the ones with the classic Hickok circuit - the ones with a #83 tube and a 5Y3GT tube inside.

BTW, you don't need to buy manuals, as most of them are available online.
 
#18
oemcar said:
... I'm looking for something bit more than just a curve or curves-
Rather, dynamic eval's of tubes when compared to Industry standard parameters - ergo rendering pass/ not pass results that can be documented. It's my supposition that gauge test values of same tube models using mutual conductance method (better than single point emission-imo) will give good idea of matching tubes. Perhaps thats oversimplification... anyone else tried this procedure to match tubes??
Click to expand...
Sure, these information can be derived from the curve data, and many curve tracers will do it for you. I know the eTracer does. PyPSUcurvetrace allows you to analyse the data in any way you want, and so will any other curve tracer that saves the data in a suitable format.
 
#19
DIYish said:
If your intention is to sell the tubes in that box, I don't think it is likely that the money you receive from those tubes will cover the expense of a tester/tracer. If you put that box of tubes on eBay in an auction, it's not likely that they will sell for more than $100, IMHO, coz I don't see popular tubes in there. I have seen similar box of not so popular tubes ending up with merely $20-60 often in eBay auctions.
Click to expand...

If sold in bulk 'as is' then I agree-
However plan is to test, document and sell individually, or by matched sets if applicable. This seems to attract best selling point.
 
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