[1000mp] Strange bahaviour on 80 meters

Thu, 25 Dec 2003 13:45:07 -0800

Has he tried changing the length of the cable between rig and amp?

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of [email protected]
Sent: Thursday, December 25, 2003 12:19 PM
To: [email protected]
Cc: [email protected]; [email protected]
Subject: [1000mp] Strange bahaviour on 80 meters

A friend has recently aquired a 1000mp, and in the process of
setting it up, we discovered that for some reason it has trouble
driving his Alpha 86 on 80 meters. The internal metering indicates
a high swr in the cw portion of that band, this resulting in a
power fold back. The tuner can be used to compensate however, I don't
think that this is dealing with the problem. Initially we thought
the problem might be with the input circuit of the 86, but with
another swr bridge in the line between the rig and the amp, the
bridge shows a flat swr when the rig "tuned" with the antenna
tuner. If the problem were with the input circuit one would expect
the amp input swr to remain constant even though the rig could
be fooled into full output by using the tuner. I suspect that
the MP is putting out out of band energy in 80 meters, thus giving
the poor swr indication. This is further confirmed by placing
an ICE 80 meter bandpass filter between rig and the amp.

Other rigs in the shack have no difficulty driving the 86 and
do not give the same high swr indication.

Am I on the right track here, or am I missing something?

Has anyone else encountered this, and if so what must be done
to fix it?

Thanks in advance.

cheers, Paul - VA7NT ex VE7CQK - email: [email protected]
"Those who hear not the music. . . think the dancers mad."
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