Randall, Randy wrote:
Possible stupid question alert. Why not measure filament current instead of
Then you do not have to worry about accounting for losses in the filament path
position of the voltmeter connection? Or is there too much variability in the
drawn from tube to tube to be useable?
As a retired broadcast engineer I can tell you: Some equipment
provide a high current shunt (100. Amperes or so for something like 62.
and a dedicated Ammeter for the monitoring the filament current of the
amplifier tube. When a new tube is installed the filament Voltage is
adjusted to the
final factory test value and that dc current is logged and that current
through out the life of that tube. (dc current for lower noise)
Such power supplies frequently feature two 24." long nichrome rods with
short between them as the filament Voltage and current adjustment.
Ron W4BIN - Understanding is much better than
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