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Re: [Amps] Measuring fil V

Subject: Re: [Amps] Measuring fil V
From: Jim W7RY <>
Date: Tue, 7 Jun 2022 12:41:21 -0500
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I'm always careful when having to use 10 KW resistors in the filament lines... I always keep one hand in my pocket on such occasions.  LOL

73, Jim W7RY

On 6/7/2022 11:58 AM, jim.thom wrote:
Be careful if using a 10 kw resistor hanging off each cathode lug on a GG
That might work if using a true rms dvm..since the dvm has a high Z input.

But if fed to an iron vane type of panel meter, you will end up with a
massive V drop across both resistors.

A pair of  low  dc resistance chokes, bypassed at cold ends to chassis, is
dead simple.  Then another pair of bypass caps at panel mounted test jacks.

Years ago, energy onix used RF chokes on one of it's  FM GG triode
amps..and the dc resistance across the chokes was too high..and resulted in
a vdrop.  When the fil V was tweaked for  'normal' under load, using their
front panel iron vane meter, the actual V at the cathode was way too high.
  This resulted in several premature tube failures.   And if a dvm was in
parallel  with the panel meter, it too will read on the low side.

Jim  VE7RF
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