Sounds like a short in the relay control cable or a problem in the xcvr.
Carl
KM1H
----- Original Message -----
From: "Alfred Frugoli" <ke1fo@arrl.net>
To: <amps@contesting.com>; "YCCC" <yccc@yccc.org>
Sent: Saturday, November 08, 2008 11:23 PM
Subject: [Amps] SB-220 saga continues
> Hello everyone,
>
> So it seems I've got a problem with my SB-220.
>
> When the amp is off, but connected in the RF path, everything is fine.
>
> When I switch the amp on I've suddenly got lots of attenuation
> happening on
> the receive path. Transmit seems fine - amp tunes OK etc.
>
> My first suspicion was that there were dirty relay contacts on the
> receive
> side. Cleaned the contacts with no success. Then I realized that the
> problem only occurs when the amp is on. So a trip to the schematic
> tells me
> I don't understand. In the RX mode the RF path through the amplifier
> should
> be the same as when the power is on. So I'm not sure where my
> attenuation
> is coming from.
>
> Just testing it a few minutes ago I can make an S5-7 station almost
> completely disappear by turning on the amp, so I've got somewhere in
> the
> area of 20db of attenuation happening!
>
> Thoughts?
>
> Thanks.
>
> 73 de Al, KE1FO
>
> -----
> Visit my amateur radio contesting blog at ke1fo.wordpress.com.
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