Hi Guys,
Per chance, does anyone reading this have any recollection as to the QST /
"Hints & Kinks" edition which made reference to regulating the 6.3 heater volts
of the 6AU6 VFO tube in the Heathkit SB-300/301 receiver...?
I have the very same malady, I'm sure, plaguing my R-4 receiver.
The station with the Drake Twins is located right between the sump room & the
forced air electric furnace of the basement: whenever either (A) the furnace,
or (B) the sump pump, or (C) the well water pump kicks in, the CW station I'm
listening to will slowly start to drift a second, or two, after said device
starts. Once the unit kicks off, the CW signal will return to "normal", again,
after the prescribed second, or two.
I suspect that unregulated heater voltage is affecting the PTO frequency, just
as it did in the referenced Heath receivers...
The "cure" in that instance (per that now-forgotten "Hints & Kinks" piece) was
the incorporation of rectifier, small electrolytic capacitor, & a zener diode
at the filament supply of the VFO tube...
Ring any bells with anybody...?
~73~ de Eddy VE3CUI - VE3XZ
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