Missing link http://home.comcast.net/~lespeters/N1sv/antennas/160.htm
----- Original Message -----
From: n1sv@comcast.net
To: topband@contesting.com
Sent: Sunday, November 1, 2009 12:02:18 PM GMT -05:00 US/Canada Eastern
Subject: Topband: Inverted-L troubleshooting
I have an inverted-L that is ~170-feet long with a vertical portion of
~60-feet. I use a surplus 7-1000 pf 5kv vacuum variable in series at the base
to resonate the antenna. The vacuum variable is housed in a weatherproof box.
I used thirty two 130-foot ground radials that connect to a steel plate. Here
is a link to fairly accurate photo though somewhat dated as the unum is no
longer used.
Toward the end of last season I started to experience a problem where if I
tried to run more then 800w into the antenna my transceiver would reboot. This
fall the problem got progressively worse restricting me to less than 400w. The
antenna resonates fine and performs well barefoot. I determined the problem
was with the antenna and not the feed-line and that it occurs with multiple
transceivers. It seems almost like RFI is being produced by the antenna and
when using high power its overloading the transceiver (no apparent affect on
my power amp).
Recently I replaced all the copper strapping used to connect various feed point
pieces together. I also removed all oxidation from the ground plate and
replaced all the lugs on the radials. This produced no improvement so now I'm
thinking maybe the problem might be with the vacuum variable. I plan on high
pot testing the cap at work but since the cap its is in series with the antenna
I'm thinking the problem might be more related to operating current then
breakdown voltage.
Has anyone had a similar problem or be able to give me some insight to a vacuum
variable failure mode that might produce this symptom.
Les, N1SV
_______________________________________________
160 meters is a serious band, it should be treated with respect. - TF4M
_______________________________________________
160 meters is a serious band, it should be treated with respect. - TF4M
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