What's my best bet for getting a decent tube tester without breaking the bank?

[suncrush]

Should I look on eBay? Somewhere else? What should I look for? What should I expect to pay?

[merlinb]

Unless you're in the business of selling tubes, you don't need a tube tester (and if you are then it's cheaper to build your own machine to test the tubes you actually sell). If you're in the business of designing with tubes, consider a u-Tracer instead:
http://www.dos4ever.com/uTracer3/uTracer3_pag0.html

[Gonzbull]

https://orangeamps.com/products/accessories/amplifier-management/vt1000/

You might be able to find one 2nd hand. It's pretty basic but it's new and won't need servicing or calibration.


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[vigilante397]

I was able to get a very clean used one on eBay for pretty cheap ($75 + free shipping) that does the job very well. And to add to Merlin's comment, if you are an amp technician it's also a pretty good idea to have one around

[amptramp]

I had a number of them and I got them all the London Vintage Radio Club.  Tube testers tend to go for $25 for an old one in good condition (at least that's what I sold my Stark AA for) and I am currently using an EMC Model 215 for octal, loktal and later tubes and I believe it was $10.  I have others that handle earlier tubes (4- to 7-pin large).  If you want a transconductance tester, you can expect to pay more.

[suncrush]

I found this.  I'll have to do my research on it, but it looks like it might be fun to make.

http://www.valveheaven.com/wp-content/uploads/2015/03/An-inexpensive-easy-to-build-diy-valve-tester.pdf

[R.G.]

Lots depends on what tubes you want to test, and what characteristics of those tubes are to be tested.

The simpler tube testers were emission testers. They fired up the heaters and then measured how much current the vacuum *diode* thus formed could pump out. Kind of a maximum current tester. Generally, the free testers in the drugstore (... and I actually remember seeing a couple of these, in a drugstore in my home town when I was a boy) had zillions of sockets and switches, but only tested emission.

There were some fancier mutual conductance testers that tested the ability of the tube's grid to back this current down. I'm foggier on the details of those.

There was wide agreement among tube technicians that the best of all testers for a tube was the circuit it was to operate in. That is, test tubes by swapping them into the circuit. Many TV repairmen made a living with a tube caddy full of tubes and time spent swapping things about.

I've theorized about building a tube tester several times. This usually takes the form of a socket setup so that various tubes could be connected, then a "dummy circuit" that tinkers with bias to set the tube in an operating-ish condition, then feeds it a signal and measures how big a signal it gets out. That's what a human with a scope would do, and is also what an "atlas peak" tester for tubes would do if there was one of those.

A super-duper version would also run a pager vibrate motor on the socket holding panel and measure microphonics, too. 

There are remarkably few tube types to test these days. Most tubes in guitar amps are 9A pinout duotriodes, and most power tubes are either compatible with the 6L6 octal layout or the seven-pin EL84/6BQ5/6AQ5 format. Not a huge crowd. The baby subminis could be adapted.

What makes all this work is a uC running things and then telling you the result. It would be far cheaper than the sockets and power supply.   

[PRR]

Use a Fender Champ (or Epi Valve Jr). Add EL84 (or 6V6) socket in parallel except with appropriate cathode resistor. Mount it so you can read pin voltages.

A 12AX7 in the first socket will read stock voltages +/-20% (probably 10%), else it is sick. Calibrate with a set of mostly-good tubes: most of them will read the same and the sick ones will be clearly out of the ballpark.

Do again with 12AT7 and 12AU7. Voltages will be non-optimal but consistent across all good tubes of a type.

Same for EL84 or 6V6, also 6L6 and EL34 (be sure to wire so G3 is tied to cathode).

When found not-sick, play! Hissy and arthritic tubes will sound bad. No common tube tester will even try to read hiss, much less "tone", but you can when tested in a working amp. (Yes, 12AU7 will need heavy strums or a boost pedal to get loud, try it and allow for it.)

[davent]

Use a Fender Champ (or Epi Valve Jr). Add EL84 (or 6V6) socket in parallel except with appropriate cathode resistor. Mount it so you can read pin voltages.

A 12AX7 in the first socket will read stock voltages +/-20% (probably 10%), else it is sick. Calibrate with a set of mostly-good tubes: most of them will read the same and the sick ones will be clearly out of the ballpark.

Do again with 12AT7 and 12AU7. Voltages will be non-optimal but consistent across all good tubes of a type.

Same for EL84 or 6V6, also 6L6 and EL34 (be sure to wire so G3 is tied to cathode).

When found not-sick, play! Hissy and arthritic tubes will sound bad. No common tube tester will even try to read hiss, much less "tone", but you can when tested in a working amp. (Yes, 12AU7 will need heavy strums or a boost pedal to get loud, try it and allow for it.)

Seven eight years ago now built this for auditioning...

dave

[thermionix]

I was able to get a very clean used one on eBay for pretty cheap ($75 + free shipping) that does the job very well. And to add to Merlin's comment, if you are an amp technician it's also a pretty good idea to have one around

Yeah get one.  Most you find are old enough to need a cap job now, clean up all the sockets and switch-witchery, usually good to go.  Try to find one from the 60s rather than 50s or earlier for the widest compatability.  Mine is an emission tester, but they pretty much all check for shorts.  Any time you can avoid putting a shorted tube in your equipment, that's a good thing.