[Heathkit] Filament Voltage Regulation

[WQ9E at btsnetworks.net]

Eddy,

I believe the article you are thinking about is "Improved Frequency Stability for the Heathkit SB-300" in the November '75 issue of QST.  

Rodger WQ9E

-------- Original Message --------
> From: Eddy Swynar <deswynar at xplornet.ca>
> Sent: Friday, September 30, 2011 6:33 AM
> To: heathkit <heathkit at mailman.qth.net>
> Subject: [Heathkit] Filament Voltage Regulation
> 
> Hi Guys,
> 
> Can anyone reading this recall a brief article that described REGULATING the 6.3-VAC filament voltage to the SB-300 receiver...?
> 
> Apparently the author of the write-up was experiencing "thermal drift" in his 300, that was attributed to the filament voltage LOWERING in his PTO oscillator tube whenever another heavy load came on-line to the AC mains. If I recall correctly, he used a voltage doubler / zener diode combination to hold filament voltage steady at 6.2 VDC just for the oscillator tube...
> 
> Does anyone recall the source of this, or am I simply having "...a senior moment"...?!   : >)
> 
> ~73~ de Eddy VE3CUI - VE3XZ
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