In the common circuit used for GG triode amplifiers that separates the B- from
ground in order to allow for convenient plate and grid current metering, there
is a 'safety resistor' from B- to ground.
Most designs seem to use a value like 10 or 20 ohms. As G3sek
<http://www.ifwtech.demon.co.uk/g3sek/> points out, if you use the 'voltmeter
method' to measure grid current, the high value of the shunt resistor requires a
higher value for the safety resistor (he suggests 1000 ohms) to keep the grid
metering accurate.
My question is: What malfunction is this 'safety resistor' protecting us
against? What could happen if it were omitted or opened in service?
73,
Vic, K2VCO
Fresno CA
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