how high is the tower
what other antennas/beams are on the tower
how high up is the tap
how many radials do you have out
Did you check to see if the connection to the radial ring (or what ever you
use to connect to the radials ) is still good? (my connection to the radial
ring had been cut and my vvc would not find a match in the ARRL 160 contest)
73
Chet N4FX
----- Original Message -----
From: "Kim Elmore" <cw_de_n5op@sbcglobal.net>
To: <towertalk@contesting.com>
Sent: Monday, December 29, 2008 5:23 PM
Subject: [TowerTalk] Now this is maddening...
> I've been shunt-feeding my tower for awhile now using an L-network
> and a motor-drive to adjust a vacuum variable. Until recently, all
> has been just hunky-dory. However, last night it appeared that my
> motor drive no longer worked as I couldn't adjust the match. What's
> more, the match started to act flaky, with variations that appeared
> to act randomly.
>
> Today I opened up the box that holds the matching network and found
> that there was some water inside and that the nuts holding the SO-239
> connectors had corroded on the inside. Water had deposited some dirt
> and detritus on the inside of the SO-239 and it was wet. So, I
> cleaned everything out with alcohol (91% isopropyl).
>
> Found the motor drive was a bit cranky, so I lubed it up and assured
> my self that it worked as it was supposed to. But, no matter how I
> adjust things, I no longer can get a match. I checked the vacuum
> variable and it appears ok -- the mechanism works and all and it's
> not shorted. All the wiring is intact. The shunt is still connected,
> the grounds good, the antennas up top still work and are intact, etc.
> The capacitor that's in there is a 5-500 pF, so as a sanity check I
> substituted in a 7-1000 pF that I have laying around. Still no match
> can be found. The transmission line checks good, so that's not it, either.
>
> Anybody else ever seen this? What have I missed?
>
> Kim Elmore, N5OP
>
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>
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