View Single Post
  #5   Report Post  
Old December 17th 06, 05:07 AM posted to rec.radio.amateur.antenna
Mike Coslo Mike Coslo is offline
external usenet poster
 
First recorded activity by RadioBanter: Nov 2006
Posts: 116
Default Mystery antenna problem

ml wrote in :

i'd guess you won't really know w/out a detailed physical inspection
unless somthing happens drastic when it rains vs a long dry spell

sure the coax could have gone bad but you have a nice meter seems
you could actually test it ,

any chance animals chewed any of the coax did anything touch the
raditors such as a branch or such perhaps near a endpoint tie off?

prb i am not much help but good luck




Thanks to everyone for the input.


As it turns out, the problem ended up being something else
entirely. I replaced the coax the other evening, and indeed it changed
the VSWR. But it still wasn't correct! Ith just moved it on the other
side of where I wanted it - what was once minimum SWR at too high a
frequency was now at too low a frequency (on 80-75 meters. Then the 40
meter was spot-on, and 20 meters was still off.

Seriously confused, I thought for a few seconds. Why on earth would
this weird stuff be happening? Then it hit me. THe OCF is not terribly
critical as far as lengths go, but it depends on the height from ground
to determine SWR and where that SWR is best. My antenna and support
structure was hit pretty hard by the storm we had a couple weeks ago, and
probably stretched a bit, and wasnt at the same height as before.
(drooped) I suspect that the 40 meter shift, and the 20 meter SWR problem
was caused by the drooping ends which didn't get beat up in the storm.

I took it down today, and put up a general purpose dipole running
through ladder line and a tuner. Working FB now.

- 73 de Mike KB3EIA -