Vic, A series circuit resonant at 30 meters will do a good job of shorting out the 40 meter inductance (no relay) - but the inductor used for 40 meters would have to be modified to compensate for the effect of the series circuit when on 40 and produce the same resultant inductance.
73, Don W3FPR > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Behalf Of Vic K2VCO > Sent: Thursday, December 08, 2005 11:30 AM > To: Elecraft Reflector > Subject: Re: [Elecraft] Clever antenna tuning ideas wanted > > > I'd like to thank everyone for their suggestions on how to make my 32' > vertical with 8' elevated loaded radials perform on 80 and 30 meters as > well as 40. > > It's clear I will have to do some major surgery on the antenna to add 80 > meters, such as a trap plus a toploading wire, or a movable wire (N6WG). > Otherwise, the high reactance and low radiation resistance at the base > will remain a problem. AB9CA pointed out that a tuner at the base could > efficiently handle a low resistance if the reactance were tuned out by > some top-loading. > > For 30 meters there seem to be some elegant solutions. W3FPR mentioned > that two symmetrical radials are enough, and EZNEC agrees that the > difference in overall gain between two and four is less than 0.1 db! > > One approach would be to separate the two pairs of radials and feed them > each through an appropriate inductance (about 11.5 uh on 40 and 1.7 uh > on 30). This would resonate the system on both 40 and 30 meters. I also > noticed (thanks, EZNEC) that with all four radials connected together, > all I would have to do is short out the existing 40 meter inductance to > obtain a low SWR on 30! But that would require a switch or relay which > I want to avoid. > > -- > 73, > Vic, K2VCO > Fresno CA > http://www.qsl.net/k2vco > _______________________________________________ > Elecraft mailing list > Post to: Elecraft@mailman.qth.net > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.1.371 / Virus Database: 267.13.12/194 - Release Date: 12/7/2005 > > _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
