Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml
Date: Wed, 01 May 2002 22:07:26 -0400
Message-ID: <redirect-1210381@logan.com>
From: "C Krouse" <kc16@qwest.net>
References: <list-1210102@logan.com>
Subject: Re: [LML] Re: Transponder Crackling - LNC2
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I have also had this problem with
> Cairns approach (near Dothan AL) on their freq that is around the 133-134
> range.  Any suggestions?  Is it my radio?  Thanks.
>
> Steve


Steve,

It very well could be your radio.  But, more than likely it's your antenna
or it's related transmission characteristics.  If you have a "commercially"
made antenna, then the element itself might not be bad, however, the cable
length could cause a strange VSWR (voltage standing wave ratio) problem.
You could talk to a local ham radio operator and find out where you can get
a SWR meter for the freq. range.  You can use a SWR meter to look at the
difference in forward power and reverse power at the trouble freqs and
compare it to the good freqs.  This will give you an indication whether your
power is bouncing back to the radio or being transmitted into the air.  If
it's being bounced back, then you may need to adjust the length of your
cable.  It could also be due to a bad connector, so make sure that you take
that into consideration.  If the cable and antenna SWR ok, then you need to
look at other metal objects close to the antenna to find out what might be
absorbing the radiation.  If you have metal objects in your radiation path,
and they have the right characteristics, they can sink the signal and
attenuate it to a point where the transmission is terrible.  That problem is
much more difficult to correct.  It could mean moving the antenna location.

Just some thoughts.

Curtis Krouse N753K