Phil,
How about using a selsyn to turn your capacitor? It will require some RF
isolation, but that shouldn't be hard.
73
Frank
W3LPL
---- Original message ----
>Date: Thu, 1 Sep 2011 08:57:33 -0500
>From: "Phil Clements" <philclements@centurylink.net>
>Subject: Topband: Antenna Matching Question
>To: <topband@contesting.com>
>
>Much has been written about matching 160 meter shortened vertical antennas,
>but very little about 160 meter antennas that are too long. There were two
>great articles in the old "Communications Quarterly" in 1998 about elevated
>ground planes, but I have lost them over the years. My current system was
>built from these articles.
>
>
>
>The system here is a 195 foot Rohn 25 tower, with insulators at the 60 foot
>level. The five sets of guy wires are all insulated from the tower, and
>additional insulators along their length to be invisible to 160 meter RF.
>The guys at the 60 foot level, just below the tower insulators are utilized
>as the radials that form the ground plane. They are 110 electrical degrees
>long. The system resonates at 1510 KHz, requiring a capacitor connected
>across the feed point. 600 pf brings the system into resonance @ 1830 KHz.
>
>
>
>There will soon come a day when I will not be able to climb to the 60 foot
>level to adjust the matching capacitor when needed. The question is: Can I
>place the capacitor at ground level, connected to the original feed point
>via coax or open-wire line? Will this 60 foot line radiate? I do not want to
>upset the radiation pattern of the system. I tried a motorized vacuum
>variable several years ago, but it was a high maintenance item due to
>exposure to the elements.
>
>
>
>I am open to all suggestions; perhaps some brand new ideas will surface from
>all the expertise on this reflector! After 57 years on the air, I am still
>learning, and trying to make improvements here!
>
>
>
>Thanks in advance for any/all comments.
>
>
>
>(((73)))
>
>Phil, K5PC
>
>_______________________________________________
>UR RST IS ... ... ..9 QSB QSB - hw? BK
_______________________________________________
UR RST IS ... ... ..9 QSB QSB - hw? BK
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