[Amps] filament voltage dropping??

[Phil Clements]

> Subject: [Amps] filament voltage dropping??
> 
> Are there any advantages to dropping on the primary side or the secondary
> side ? This is on a K2RIW style amp for 432 mhz. The tubes are a pair of
> 8930s. I need to go from 6.3 to 5.5 or so. Mike

Mike, I always use the method used by Henry Radio here. Get a large (50-100
watt) adjustable resistor and put it in series with one side of the primary
winding. Adjust the slider to the desired voltage, measured at the tube
pins. Then you have the ability to keep the voltage right at the
"sweet-spot," just a bit lower than factory specs. This resistor also
slow-starts
the filaments at every turn-on, with no moving parts.

(((73)))
Phil, K5PC