[R-390] QSK; standby reduced fil. voltage; separate B+ on/off

[Henry Meils]

Hi

1. Does anyone have experience with an alternative idea for full QSK R-390A operation; ie. to avoid the clacking relay noise.

2. Was thinking of running  always-on reduced standby filament voltage, especially on VFO - ( full voltage when operating)  for frequency stabilty
    and prolonged tube life. I understand that commercial broadcast stations run never-off full filament voltage on their PA tubes to prolong life time.

3. Adding a separate HV/B+ switch, maybe resistance stepped, so first reduced then full HV/B+ after filalment warm up (at full rated voltage).
   (would have to consider effect on tube contra CR rectifiers C when switching HV/B+ current load).

4. Just using an ac-line variac without a HV disconnect can be detrimental when plate/sceen current flows before filaments hav reached proper temperature.

vy 73s, Henry, OZ1UF-Copen.