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Peter Wieck Peter Wieck is offline
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Default Restoring a TV-7/U Tube Tester

On Thursday, October 16, 2014 4:25:39 AM UTC-4, Patrick Turner wrote:

Much snippage


I was given maybe 4 tube testers over the 20 years after 1993 when I decided to become as near an expert as I could with audio amps and radios using tubes.


I never came across a tester from 1960s which may have actually survived the technicians who used it. In theory, if any tube has an internal short circuit then it should not hurt the tester if you plug it in with correct switch settings.


I also have a few ancient tubed oscilloscopes, and some dismantled vacuum tube voltmeters. All are complete junk compared to much stuff I have acquired which was made after 1980, with not a vacuum tube to be seen.


I keep two testers - a diddly-simple Simpson emissions-tester that also handles shorts and gas that fits 99-44/100ths of the need, and a very nice, well-kept, properly calibrated Hickok 539B late of the GE Re-Entry Systems Division in Philadelphia before it closed down these many years ago. Both have been out-of-case cleaned and calibrated (in the case of the Simpson, to the extent it can be) and both do nicely.

At the same time, the only valid test of any vacuum tube is its circuit. A tester is not much more than a go/no-go device in most cases.

Getting to that 66/100ths use(s): Matching. Some few circuits prefer reasonably matched tubes at least initially. And very, very few testers are capable of actually matching. The Hickok 539 series (A,B,C) can match - albeit with one or two additional outboard VOMs attached.

And, of course, the big honking tester with three meters and enough switches to be massively confusing does impress the impressionable.

I do have all the update pages (through 1990 anyway) for both testers, so there are few tubes that are not listed. And I have acquired WE test data for the Hickok - as they made the WE testers under license.

But with all of that, and all the equipment that passes through my hands the either tester seldom sees the light more than 3 or 4 times per year outside Kutztown, where the 539 is in heavy demand by the tube vultures - the club performs free tests at the Clinic table.

Peter Wieck
Melrose Park, PA