>
>I'm not sure if this has been brought up before, but wouldn't the best way
>to get a truly accurate reading of filament volts on a glass tube like a
4-1000
>would be to solder small wires directly to the filament pins and run them to
>an accurately calibrated AC voltmeter?
Soldering wires to the pins would serve no purpose since the test prods
to the DMM can be applied directly to the filament pins.
>There can be a small amount of
>resistance where the socket grips the tube pins and in a high-current
>filament circuit even a small resistance can drop the filament voltage some
>fraction of a volt?
True. The V-drop from the socket contact to the pin could be measured.
My guess is that <50mV drop would be ok.
> Is it feasable to measure the filament voltage at the
>pins in an operating GG amplifier where the filament circuit is above ground
>hot with RF? I would think using a pair of small RF chokes at the pins would
>isolate the AC voltmeter from the RF but could they cause problems with
>making the circuit unstable? Has anyone ever done this? Thanks for any
>comments.
The presence of RF adds virtually no useful inforation.
cheers, Todd
- R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures.
end
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