[Boatanchors] Fw: QSK; standby reduced fil. voltage; separate B+ on/off

[Henry Meils]

----- Original Message ----- 
From: Henry Meils 
To: 
Sent: Sunday, October 18, 2009 12:36 PM
Subject: R-390A & other BA rx: QSK; standby reduced fil. voltage; separate B+ on/off


Hi

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

And also regarding the R-390A:

2. I was thinking of running  always-on reduced standby filament voltage, especially on VFO - ( fil voltage turned to rated value 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, intially reduced then followed by  full HV/B+ after filalment warm up (at full rated voltage).
   (would have to consider effect on tube contra CR rectifiers when switching HV/B+ from reduced to full 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.