Hi Jim,
If you base load a 68 vertical on 160 meters it will create very high voltage at the base of the vertical which may damage the base insulator. Much better to use top loading to avoid high voltage at the base. 73 Frank W3LPL ----- Original Message ----- From: "Jim Garland" <[email protected]> To: [email protected] Sent: Sunday, September 2, 2018 10:03:32 PM Subject: Re: Topband: Air wound coil On this general topic, I'm erecting a 68 ft aluminum self-supporting pole (DX Engineering) that is four inches OD at the bottom, tapering to about 1/2 inch at the top. It is designed as a full size 1/4 wave 80m vertical. I'd like to use it on 160m. If I add four capacity hat wires at the top, would that sufficiently lower the resonant point? The antenna tilts at the base with a hand winch, so it's not hard to add or remove wires if I want to restore the antenna to 80m. The other option is to add inductance at the base (easy to do), but I don't know if that is the preferred solution or not. BTW, there are sixty 30m radials already installed at the base, from a previous antenna. I only care about resonating the antenna near the low end of the band. Except for cacti and coyotes, the antenna is 200m from any structure, fed with buried hardline. Any suggestions? Thanks! 73, Jim W8ZR _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband
