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

[David C. Hallam]

Get an old fashion TR switch like Johnson or B&W made, no modifications 
or changes to anything needed.

David
KW4DH

Henry Meils wrote:
> 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.
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