[R-390] bfo problems

[Walter Wilson]

Steve,

As Jim said, check the PTO tube.  But while you're in there, make sure the
metal L-shaped grounding strap that contacts the PTO shaft is making good
contact.  This is the electrical ground for the PTO shaft, and should NOT
have any lubrication applied.  If any is there, remove it.  If the PTO shaft
is not grounded properly, the oscillator will warble.

Walter Wilson - KK4DF
http://r-390a.us
(REAL Radios: R-390A, R-390, T-368E, Ranger, Thunderbolt, KWM-2A)

----- Original Message -----
From: "Steve Hobensack" <stevehobensack@hotmail.com>
To: <r-390@mailman.qth.net>
Sent: Thursday, January 02, 2003 6:52 PM
Subject: [R-390] bfo problems


> My r-390a has a slight hum when the bfo is on. Cw and ssb signals have a
> slight "vibrato" sound. Cw notes are not clean and crisp with any setting
of
> the mgc level. I suspected one of the filter caps, but they are ok. The
> decoupling cap on the bfo 150v b+ is ok , there is no cathode to filiment
> short. I turned off the bfo switch, and injected a 455 khz carrier from my
> urm-26d signal generator to pin 5 (plate)of the tube socket. I still had
the
> hum with the signal generator acting as the bfo. The radio sounds fine
> listening to a m broadcast. Any ideas ???  Thanks
> .......Steve.....KJ8L
>
>
>
>
>
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