At 08:45 AM 10/6/2005, K7LXC@aol.com wrote:
>Howdy, TowerTalkians --
>
> I've got an antenna problem and I'm stumped. An M2 15M monobander
>developed some high swr - 3:1 or more where it used to be 1.1:1.
>
> I took a crane and man-basket up to the feedpoint and measured the swr
>with my MFJ at the balun; it was 1.2:1. I next measured at the jumper to the
>tower - same thing. Then I measured the end of the feedline in the shack -
>same
>thing. As far as I was concerned, the antenna system was fine.
>
> Plug it into the FT-990 and the swr on the rig was 3:1. Antenna tuner
> was
>off. Add different lengths of RG-8, the swr varied from 2.5:1 to 5:1. It
>doesn't seem to be wx related.
So, with the MFJ at the shack end of the coax, everything is fine, but the
rig shows the bad SWR?
Certainly, adding coax shouldn't change the SWR (at least that much)
Is the problem power related? Perhaps a small piece of debris in a
connector is arcing over? Has the rig's owner been annoying someone
prompting the proverbial "pin in the coax"<grin>?
Realistically, has the coax been crimped or damaged somewhere? You could
have a big void in the dielectric, or a fuzzy hair sticking in somewhere,
and at low powers you won't see it, but when you apply power it
shorts. (which would result in a changing SWR with length, hmmm...)
> Like I said, I'm stumped. Any help out there? Solutions appreciated!
>
>Cheers,
>Steve K7LXC
>TOWER TECH
>_______________________________________________
>
>See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
>Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
>any questions and ask for Sherman, W2FLA.
>
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_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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