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My take on your situation: The two C3SS's will couple each other heavily. Likely loss of f/b ratio, impedance changes, and moderate loss of gain. The trapped dipole will have little interaction with the C3SS above due to C3's short boom and elements insulated from the boom. Much better setup for contesting: 1) Sell the Mosley tribander. Use the proceeds to buy a Ham IV rotator. The CC dipole will perform as well as the Mosley, but in two directions at the same time. 2) C3SS at 78 feet on rotator. Very light rotator needed for C3SS. Mount trap dipole on rotated mast 3 or 4 feet above or below C3SS parallel to boom. This will place it at an effective height for 40 meter usage. It will also get SA or Carrib on 10-20 with the C3SS pointed at EU, and allow you to listen for JA opening while working EU. 3) C3SS at 45/50 feet or so fixed on CA for local contests, on EU for DX tests. 4) Spring for the small stackmatch so you can stack the two C3SS on EU for DX tests, very effective. Put the rotatable dipole on the third antenna jack of the stackmatch. Single feedline setup to shack, and can feed at same time with other antennas. 5) Read up on guy wire interaction, and modify your guy wires (insulators, etc) if needed to minimize interaction. The above a minor variant of arguably the best setup going for (relatively) inexpensive 70-ish single tower setup. 73, Guy. On Mon, 10 Jul 2000 13:56:23 -0400, you wrote: >Comet GP-15 6-2-440 vertical with its base at about 80 feet. > >C3SS below the Comet at 78 feet fixed E on Africa >(I am guessing that only the "tuning section" on the Comet is an issue?) > >C3SS below at 68 feet fixed W/NW across TX towards CA. > >Cushcraft C4 40-20-15-10m trapped dipole at 65 feet >(Parallel to the boom of the C3SS immediately above.) > >Mosley trapped tri-bander at 45 feet fixed S/SW on central/so America. > >- Thanks! & 73, DavidC K1YP in Hudson, FL >************************************************************************ > >On the surface of it, it would seem like excessive interaction. To be >specific, >can you provide the actual planned height of each individual antenna *AND* >their fixed orientations if fixed? > >On Mon, 10 Jul 2000 12:25:45 -0400, you wrote: > >>I am planning to stack two C3SS beams on the same tower as >>several other antennas. >> >>Here is the planned stack -- I need to know about spacings. >> >>Comet GP-15 6-2-440 vertical with its base at about 80 feet. >> >>C3SS below the Comet >> >>C3SS below the C3SS (pointed in a different direction than the top one) >> >>Cushcraft C4 40-20-15-10m rotatable dipole >> >>Mosley trapped tri-bander >> >>NOTE: The tower is a 70 foot Rohn 45 with 12-14 feet of mast out the top. >> >>- Thanks! & 73, DavidC K1YP in Hudson, FL >>************************************************************************ >> >> >> NetZero Free Internet Access and Email >> http://www.netzero.net/download/index.html >> >> >>-------------------------------------------- >>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 >> >> > >73, Guy >k2av@contesting.com >Apex, NC, USA > > > >Why pay for something you could get for free? >NetZero provides FREE Internet Access and Email >http://www.netzero.net/download/index.html > > >-------------------------------------------- >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 > > 73, Guy k2av@contesting.com Apex, NC, USA -------------------------------------------- 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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