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Natan suggested I re-post this subject and make it slightly more concise. Here I go: I have a C-4e (with the 40m dipole cut 7.060) at about 52ft. I have an Inv-V for 80m (cut 3.550) about 6ft beneath it (and a 160 Inv-L at that same level). All four antennas switched with an Ameritron RCS-8 (5 feed switchbox). I notice, and I'm living with, some interaction on the 40m dipole when I swing it on the rotator. I presume it's the proximity to the 80m Inv-V? The Swr rises as the element lines up with the dipole and drops off when perpendicular. I tried to put up another dipole for 80m ssb (3.790) another 4ft or so below the first - but, it interacted too much with the existing 80m and the 40m problem obviously remained. I tried another 40m Inv-V, cut to 40m ssb (7.225) - but with even more of a problem with the C-4e. It's now a 30m dipole at about 36ft on the 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 (grounded) unused antenna positions cure or minimize the interaction problem? 2) Is there a suggested length of the 40m feed after the switchbox (with respect to the length of the other C-4e feed length?) to help lower any interaction and spikes in Swr as it rotates? Hope that's easier to understand. Thanks for any input! David VE3STT ve3stt@rac.ca -------------------------------------------- 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 |
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