[amsat-bb] Re: accidental RF into wrong cable of Arrow=bad duplexer?

[i8cvs]

----- Original Message -----
From: "Tim Goodrich" <tim at timgoodrich.net>
To: <amsat-bb at amsat.org>
Sent: Sunday, October 11, 2009 10:51 PM
Subject: [amsat-bb] accidental RF into wrong cable of Arrow=bad duplexer?


> I am an owner of a 2m/70cm LEO satellite antenna with duplexer in the
> handle. Sometimes, I operate full duplex (two radios) and bypass the
> duplexer by attaching my own cables to the separate parts of the antenna
(1
> radio for 2m, 1 radio for 70cm). In the course of rushing to catch a
> satellite pass, I mixed up my connections and accidentally transmitted (5
> watts) into one of the arrow antenna cables, causing RF to feed backwards
> into the duplexer.
>
>
>  Recently, I have noticed decreased performance (poor reception, lower
S/N,
> even on AO-51 when in the past it was full quieting) and am trying to
> ascertain if it could have anything to do with my mistake of feeding RF in
> the wrong direction into the duplexer. Could my mistake cause this
problem?
>
> Thanks,
>
> Tim
>
> KI6VBY
>
>
Hi Tim, KI6VBY

If I well understand you connected the VHF antenna to the UHF connector
of  your duplexer and the UHF antenna to the VHF connector of your
duplexer while transmitting by mistake.

A duplexer is essentially a low-pass filter at VHF and a high-pass filter at
UHF having in the middle the common connector going to a VHF/UHF
tranceiver.

If you reverse the antennas at the output of the above duplexer the only
effect will be a very high VSWR in both bands VHF and UHF but no
damage will involve the receivers.

Best 73" de

i8CVS Domenico