23-09-2019, 11:38 AM
The triode is biased by contact potential using the 20MΩ resistor direct from grid to cathode. It's not my favourite method of biasing a valve, but it does work and for now I'd counsel Amie not to fix (yet) what ain't broke.
At the moment we don't know how Amie is deriving her bias (battery maybe, with trimmer potentiometer? Or a bench power supply?) but for experimental purposes, it presumably works. Refinements such as replacing with a resistor are for the future, but may also be awkward depending on the HT source negative rail!
At the moment we don't know how Amie is deriving her bias (battery maybe, with trimmer potentiometer? Or a bench power supply?) but for experimental purposes, it presumably works. Refinements such as replacing with a resistor are for the future, but may also be awkward depending on the HT source negative rail!
