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Old 3rd Dec 2015, 12:27 am   #95
MotorBikeLes
Octode
 
Join Date: Dec 2012
Location: Kirk Michael, Isle of Man
Posts: 1,536
Default Re: Test equipment for valve radio repair

In my teens I acquired an avominor which was used for many tests for years (including motorcycle electrics. When I began playing more with electronics, I bought a Grundig Valve voltmeter. It had no case, just the top section. I made a box it would drop into. Very impressive. Shortly after I picked up a Phillips (or Mullard) DC valve voltmeter. It was a non-runner, and I diagnosed it as having all valves with O/C filaments. They were all 1.4v B8G (??) types (EL41?? etc). The input was chopped by a well sealed up aluminium vibrator. Quite different physically to the type used in car radio PSUs. I vaguely recall that its input resistance was supposed to be in the 100's of megohms. I suppose the vibrator was similar to the Honeywell used in some of our potentiometer temperature instruments which required accurate results of around 10mV to a couple of decimals.(almost 50 years ago, so I forget exact details.
Les.
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