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I sent this off to another reflector, but thought it also related here. The yagi I'm talking about is a C-4e. Any additional input (if it hasn't already been covered) would be helpful! David VE3STT ve3stt@rac.ca ----- Original Message ----- From: "David Jones" <djones449@home.com> To: "TowerTalk" <towertalk@contesting.com> Sent: Monday, April 23, 2001 8:19 PM Subject: Re: [TowerTalk] C31XR / CC 402CD Question > Dave, > Not to take us off topic, but your posting raised a somewhat related > experience I am having right now and I would love your input. > I have a tribander/40m dipole (cut 7.060) yagi at about 52ft, along with > Inv-V for 80m (cut 3.550) about 6ft beneath it (and a 160 Inv-L at that same > level, but not part of this concern). That's four antennas all switched > with an RCS-8 (5 feed switchbox). > I tried to put up another dipole for 80m (3.790) another 4ft or so below the > first - way too much interaction with both the original 80m and the 40m (in > fact the original 40m shows interaction as you swing it around on the > rotator, I presume with the 80m dipole?). > So I then tried to cut the dipole down to 40m (7.225) - still a problem with > interaction. > It's now a 30m dipole much lower on the tiny tower, and not causing a > problem (I can see). > My questions (after all this): > 1) Does the setup of the RCS-8 play a role in causing (or hopefully > eliminating) interaction. I believe it comes from the factory with "open" > positions for the unused antennas. Would shorted unused antennas cure the > problem? > 2) As you suggested, is there a way to "play" with the length of the feed > after the switchbox to help lower any interaction and spikes in Swr as it > rotates? > Thanks for any input! > > ----- Original Message ----- > From: "Dave Hachadorian" <k6ll@juno.com> > To: <towertalk@contesting.com> > Sent: Tuesday, April 24, 2001 5:04 AM > Subject: Re: [TowerTalk] C31XR / CC 402CD Question > > > > > > > > On Sun, 22 Apr 2001 23:05:42 -0400 "Guy Olinger, K2AV" > > <k2av@contesting.com> writes: > > > > > Get your tribander of choice and prepare to possibly > > > operate > > > them at right angles, where the 402CD has been reported to work > > > well. > > > > The 40-2CD works well aligned with a nearby tribander. Mine is > > only 6 feet above the tribander. The loading coils in the 40-2CD > > elements move the third harmonic resonance to about 18 Mhz. In fact, > > the 40-2CD makes a very good 17 meter antenna, with a deep null off > > the sides, and swr ~ 2. > > > > The only thing you need to worry about on the 40-2CD, and probably > > any close-spaced beam, is the random length of feedline dangling > > off the driven element of the 40, while the tribander is being used. > > This feedline can shift the resonance of the 40 driven element into > > the higher ham bands. A good way to test for this effect is to > > repeatedly short, then open, the 40 meter feedline, while observing > > swr on the tribander to see if it changes. If it does change, > > experimentally change the length of the 40 feedline. > > > > Dave Hachadorian, K6LL > > Yuma, AZ > > K6LL@juno.com > > > > List Sponsor: ChampionRadio.com - Trylon self-supporting towers, > > safety equipment, rigging gear, LOOS tension guages & more! > > http://www.championradio.com > > > > ----- > > FAQ on WWW: http://www.contesting.com/FAQ/towertalk > > Submissions: towertalk@contesting.com > > Administrative requests: towertalk-REQUEST@contesting.com > > Problems: owner-towertalk@contesting.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 n4zr@qth.com |