[ARC5] OT? bc-348 bfo question

[Bill Carns]

Just checked the gimmick wires on my minty never-been-molested Q and it is
three turns of insulated wire wound around the stub wire close spaced and
tight wound.  But.....I am in agreement with the folks who have come up
saying that the BC-348 is not a SSB receiver and the symptoms you describe
would be what I would expect with a receiver that you could not turn the
audio all the way up and reduce the signal into the BFO mixer by varying the
RF Gain.

I am not sure it is "broke".


Bill
N7OTQ

-----Original Message-----
From: arc5-bounces at mailman.qth.net [mailto:arc5-bounces at mailman.qth.net] On
Behalf Of Fernando - LU2DFM
Sent: Friday, September 13, 2013 7:38 PM
To: arc5 at mailman.qth.net
Subject: Re: [ARC5] OT? bc-348 bfo question

On Fri, Sep 13, 2013 at 07:37:09PM -0400, Jay Coward wrote:
> Check the feedback "gimmick" capacitor. It's a couple of twists of two
wires.
> Jay

Thank you; I'm thinking alike. The gimmick looks like original to me, and
it's pretty small: the wire from the BFO coil goes over the plate wire, but
does not coil around it. I think this is too little coupling.

My feel is that the output of the BFO is too small to get enough carrier
into the detector for moderately strong signals and up. The plate voltage of
the triode section of the 6F7 varies between some 45 to 32 volts as the RF
gain is varied (MVC, no AGC position). That's pretty near what the manual
indicates. 

Tomorrow I'll take some meticulous measurements and will decide if more
gimmick capacitance is needed or there's something wrong in the BFO.

Does anyone has a photo of an original gimmick cap? 


--
73 de Fer, LU2DFM
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