Not saying this might be a good idea, it just sounds more like a weak tube. Typically when a tube goes end of life, its emissions are down, and voltage would play a much greater role on the filament.
That said, if you are an ARRL member you can search the archives for SB-300 and get several hits. One being Nov 1975 pg 37, improved freq stability for the Heath SB-300. I can not read it as my upgrade of adobe on this machine blew up. Until I figure out what happened, no PDFs. 73, Ron WD8SBB --- On Thu, 12/30/10, Diane and Edward Swynar <[email protected]> wrote: From: Diane and Edward Swynar <[email protected]> Subject: [Drakelist] Drake R-4 PTO Heater Regulation To: [email protected] Date: Thursday, December 30, 2010, 1:10 PM 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 -----Inline Attachment Follows----- _______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist
_______________________________________________ Drakelist mailing list [email protected] http://mailman.zerobeat.net/mailman/listinfo/drakelist
