Or a couple of relays to select band segment fixed caps. I did that at a prior QTH on 160 using 24VDC new surplus relays from All Electronics.
Carl KM1H ----- Original Message ----- From: <[email protected]> To: <[email protected]> Sent: Thursday, September 01, 2011 11:58 AM Subject: Re: Topband: Antenna Matching Question > 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 > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 10.0.1392 / Virus Database: 1520/3872 - Release Date: 09/02/11 > _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
