[1000mp] High swr

Thu, 13 Feb 2003 07:56:40 -0500

At 14:19 -0500 2/12/03, George & Marijke Guerin offered this for consideration:
>
>If only on certain bands or low bands only give high SWR, then for those
>bands with problems, the band pass networks or their switching logic are not
>functioning properly

The problem I've been having for the last several months (since it's 
been too cold to go outside to fix it) is intermittent SWR on the 
bands 20 through 10 meters, on my 1000MP. These are the bands for 
which I use my quad antenna, fed with one coax through a balun at the 
antenna.

The problem is the worst on 20 meters, getting gradually less until I 
get to 10 meters, where I very rarely experience it, if at all.

I've changed all connections, coax routing, tuner connections, etc. 
outside the radio, except the feedline to the quad, which was newly 
replaced late last summer (_maybe_ this is when the problem started, 
but I can't pinpoint it that closely).

I wanted to blame the radio or something inside the radio, but when I 
connect the radio directly to a dummy load, the SWR is perfect on all 
bands with no intermittent behavior.

The power meter on the 1000MP looks normal, giving full power when 
the SWR is low and gradually decreasing as the SWR indication 
increases. This happens whether or not I'm using the auto antenna 
tuner in the radio.

I have a replacement balun in hand for the quad, since it's one of 
the last things I haven't yet checked, but it's a fully potted device 
and it's hard to believe something might have gone wrong there in 
only two and a half years in the air.

I should mention that I don't own an amplifier and never run more 
than 100 watts.

As soon as the weather breaks and we get some warmer days (at the 
rate _this_ winter is going, that should be about June) I plan to go 
up the tower and first try a different feedline and, if that doesn't 
cause any change, replace the balun on the quad, hopefully to bring 
this problem to a halt.

Am I missing something? Is there something in the radio that could be 
causing this problem only when going to the antenna and not when 
going to a dummy load? Does anyone have any other ideas?

Thanks for any help you can offer.

73,
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