[R-390] bfo problems

Thu, 02 Jan 2003 19:50:02 -0500

Hi,

My bet would be AC modulation of one of the oscillators. Most oscillators
will FM before they AM so low level modulation would only be apparent with
the BFO on. Going *way* out on a limb - check the PTO first.

    Take Care!

        Bob Camp
        KB8TQ

----- Original Message -----
From: "Steve Hobensack" <[email protected]>
To: <[email protected]>
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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