Author Topic: Vacuum Tube tester?  (Read 2524 times)

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Offline MrZwing

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Vacuum Tube tester?
« on: February 04, 2015, 05:13:14 pm »
I'm planning to build some different circuits with vacuum tube's in the future an thought having a Tube tester would be nice to have.
Now I wonder is there any recommended tester out there that are in the "start-up" price range or if there is some way to build one. an are they still built by enthusiasts or should I look at the vintage type?

/MrZ
 

Offline T3sl4co1l

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Re: Vacuum Tube tester?
« Reply #1 on: February 04, 2015, 11:50:07 pm »
Most any basic "good/bad" tester is simply a diode mode (emission) tester.  They may also do grid leakage and shorts.  You can test for a weak cathode by reducing heater voltage by one step, and more thoroughly test grid leakage (if so equipped) by increasing heater voltage by one step.

The really fancy ones (including the Hickoks that go for >$300?) perform these tests quantitatively (rather than qualitative good/bad), and also perform transconductance and perhaps other tests.

If you don't mind spending the time, you can also set up a breadboard to do the same.  For transconductance, simply set up the device at the datasheet conditions, feed in a small AC grid voltage (maybe 0.1V), and see how much AC plate current comes out.  The load resistance should be relatively small, a fraction of the plate resistance, to measure Gm directly without interference from plate resistance (which of course is more important for triodes than pentodes).

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Offline albert22

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Re: Vacuum Tube tester?
« Reply #2 on: February 05, 2015, 01:46:33 am »
Something like this may be useful for your project:
http://www.dos4ever.com/uTracer3/uTracer3.html
Similar DIY tube curve tracers can be found on the web.
 

Offline Electro Fan

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Re: Vacuum Tube tester?
« Reply #3 on: February 05, 2015, 07:23:08 am »
As a frame of reference for what's out there you might look on eBay.  Search on tube testers in general; take a look at Hickok - a lot of people think they made excellent tube testers - among the very best.  You can get some ideas about what features you might want to build into your DIY project, or depending on your location you might find a unit in good condition that will meet your budget.  A lot depends on the particular types of tubes you are going to be using/testing as well as the particular tests you want to run (such as transconductance as mentioned by T3sl4co1l).  The 539C is an all-time favorite (perhaps exceeded only by the 580A); probably out of your budget unless you get lucky but it would be a good study reference for nearly every function and spec ever built into a tube tester.  One other thing - be very careful poking around with tube circuits - can be lots of voltage in there.
« Last Edit: February 05, 2015, 07:25:32 am by Electro Fan »
 

Offline Seekonk

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Re: Vacuum Tube tester?
« Reply #4 on: February 05, 2015, 08:19:29 am »
Something like this may be useful for your project:
http://www.dos4ever.com/uTracer3/uTracer3.html
Similar DIY tube curve tracers can be found on the web.

Thanks for that.  Don't think I will ever need more than my Jackson, but that was an impressive read.
 

Offline MrZwing

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Re: Vacuum Tube tester?
« Reply #5 on: February 05, 2015, 08:44:03 am »
Something like this may be useful for your project:
http://www.dos4ever.com/uTracer3/uTracer3.html
Similar DIY tube curve tracers can be found on the web.

Hmm I will take a look at it.


take a look at Hickok - a lot of people think they made excellent tube testers - among the very best. 

Could maybe try and find a Service manual and see if i can get a schematic to reverse engineer and maybe improve with modern components to make it smaller. but that is a long term project for a newbie like me but always good to have some proper challenges in life.  :-+
 


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