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Author Topic: Tube testing without a tester?  (Read 3823 times)

MI

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Tube testing without a tester?
« on: January 24, 2007, 10:07:09 am »

Hello Oliver,

Sorry if this has been asked, but did a search and came up with nothing.

Is there anyway to test a tube without a tester?

Specifically EF14, EF184 and EF86.

The EF14 and EF86 are NOS, and the EF184 are used.

Thanks.

Mario.
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Oliver Archut

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Re: Tube testing without a tester?
« Reply #1 on: January 25, 2007, 12:30:12 am »

Hello Mario,

most of the tube tester do nothing else than tell you if the tube has emission or not, a tube might test good on a tube tester, but in equipment they sound poorly or is noisy, etc. so getting a reading of a tube won't really help you at all.
For my production units I do not pre-select any tubes, they come out of the box and get tested inside the newly build unit, if the voltage are in the specified range the tube get a burn in and get test for proper voltages (current) after 24 and 48h.
After the two day burn each unit gets a noise, microphonic, bandwidth test and than the final listening. That keeps the early tube failure to a minimum ,but even than there are still enough tubes that have some issues at later dates. So testing a tube does not even tell you anything...

But if you want to test a tube without a tester you have to check the data sheet for the static tube values, set the tube in question to the proper voltages and measure the cathode, grid(s) current and the specified max. plate dissipation. With a signal generator you can test amplification, etc. If your valve strays from the given tolerances you might want to discard it.

You can find nearly all tubes data sheets here http://frank.yueksel.org/tubes/sheetsA.html

Best regards,
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Oliver Archut
www.tab-funkenwerk.com

We are so advanced, that we can develop technology that can determine how much damage the earth has taken from the development of that technology.
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