In a message dated 9/8/2005 5:56:31 P.M. Pacific Daylight Time,
My filament transformer didn't have a center-tap
so I improvised a B- by using an artificial centertap made of diodes
to each leg of the filament's secondary.
This tube is NOT a directly heated cathode. It has a indirectly heated
cathode ... connection to the cathode is the outside heater connection. This
where you connect the B- through a RF choke to the tube. I found that any
B- connection to this tube will induce hum in the transmitted signal do to
the AC heater current ending up in series with the cathode B-.
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