GE Eddy:
I'm kind of going along with the others here in being very skeptical of
the cause and effect you are seeing.
I would be looking for something other than the filament voltage as the
culprit.
Does the same thing occur when the pair is set for Tx control? Have you
actually watched the power line input voltage to see what is happening
when those other motor devices turn on?
Then monitor the actual voltage at the tube.
Not saying it isn't the cause, but I'd be trying to verify it before a
DC mod.
Curt
KU8L
Diane and Edward Swynar wrote:
*/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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