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driven element configuration. One is a tribander using the coupled radiator scheme between the 20M and 15M driven elements. On both antennas, I have the spacer between driven elements located approximately 80% out on the 15M driven element. Any closer distance to the boom and the 15M driven element will still move excessively in the wind causing SWR excursions that may cause amplifier problems. I might add that the spacer is mounted securely to the 20M driven element; the spacer is free to slide on the 15M driven element as the elements swing about in the wind. One spacer on each side of the boom is adequate to maintain element tuning. 73, Phil, W9XX ----- Original Message ----- From: Jan Fisher <jan.fisher@virgin.net> To: Hank Phillips <aa4hp@titustek.com>; <Force12Talk@qth.com> Sent: Monday, May 15, 2000 12:03 PM Subject: Re: [Force 12 Talk] C-31XR 15-Meter SWR Measurements > I have had the same problem. In windy conditions my Alpha 87A trips out due > to high SWR on 15m. Not a problem when using amps without high SWR sensing. > > Used to get the same thing with the C3S but cured it with extra spacers. > > Think I will add another couple of spacers near the ends of the elements on > the C31XR > > 73 Jan > G0IVZ > -----Original Message----- > From: Hank Phillips <aa4hp@titustek.com> > To: Force12Talk@qth.com <Force12Talk@qth.com> > Date: 15 May 2000 17:38 > Subject: [Force 12 Talk] C-31XR 15-Meter SWR Measurements > > > >I guess from the questions coming back, this isn't a very common > >problem. But I'll try to answer given the instrumentation limits (i.e. no > >anemometer). > > > >When the wind is perfectly calm, I measure 1.4:1 on the Nye Viking meter in > >the shack on 21.300. At wind speeds under 20 MPH (my best guess), the SWR > >varies from 1.2:1 to 2.2:1 with a period of 2 to 3 seconds which > >corresponds directly with the observed element motion and spacing variation > >of the driven elements (15/20 meter elements). On really windy days, it's > >worse in direct proportion to the wind speed. > > > >Because of the horrendous lightning in Florida, I don't play with antennas > >much in the rain. > > > >The antenna is essentially flat at 21.150 , rising to about 3:1 at 21.450 > >and 1.3:1 at 21.000. We made no attempt to trim elements at install time, > >just played with the parallel wire feed lines and hairpin coil to minimize > >SWR on 15 and 20. Other bands are not affected by wind. > > > >Tnx es 73, > > > >Hank > >AA4HP > > > > > > > >-------------------------------------------- > >Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. > >Force 12 Web site: http://www.qth.com/force12 > > > >Submissions: send to Force12Talk@qth.com > >To unsubscribe: send a blank e-mail to Force12Talk-leave@qth.com > >Force12Talk Message Archive: http://www.qth.com/force12/list/force12talk > >For problems with the list, contact force12@qth.com > > > > > > > > -------------------------------------------- > Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. > Force 12 Web site: http://www.qth.com/force12 > > Submissions: send to Force12Talk@qth.com > To unsubscribe: send a blank e-mail to Force12Talk-leave@qth.com > Force12Talk Message Archive: http://www.qth.com/force12/list/force12talk > For problems with the list, contact force12@qth.com > > > -------------------------------------------- Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. Force 12 Web site: http://www.qth.com/force12 Submissions: send to Force12Talk@qth.com To unsubscribe: send a blank e-mail to Force12Talk-leave@qth.com Force12Talk Message Archive: http://www.qth.com/force12/list/force12talk For problems with the list, contact force12@qth.com |
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