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" <[email protected]> >Subject: Topband: Antenna Matching Question >To: <[email protected]> > >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
