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If your C3 is between the EF-240S and the guy wires, was the C3 not suspect? Sounds like it was cleared of potential interference with the 240S but I am wondering how you did that. Joe K4AW -----Original Message----- From: Pete Smith [mailto:n4zr@contesting.com] Sent: Thursday, July 25, 2002 8:55 AM To: towertalk@contesting.com; Force12Talk@qth.com Subject: [Force 12 Talk] Re: [Towertalk] C31XR & guy wire detuning At 08:12 AM 7/25/02 -0400, K7LXC@aol.com wrote: >In a message dated 7/23/02 12:50:44 PM Pacific Daylight Time, >jskatz@sk.sympatico.ca writes: > > > I want to break the 54' sections into two segments each. My question: > > > > What should the lengths of these two sections be to minimize their > > interaction with the C31XR? > > There are 2 things at work - the antenna and the guy wires. First, you >need to see if it's a guy problem by keying the radio into the antenna and >then turn it while you watch the swr. If the swr varies as it turns, then >it's guy wire interaction. If it doesn't change, you've got an antenna >problem. Steve, I think that's too simple. If the SWR doesn't change when it turns, it MAY not be a guy wire problem, but you can't be sure because not all destructive interaction affects SWR,and the placement of the guy wires may be such that their effect is more or less independent of antenna rotation. As an example, my F12 EF-240S is at 104 feet, above a C-3E and 9 feet above the tops of the uppermost guy wires, which were grounded at the bottom but insulated from the tower. Rotating it showed no SWR variation, but the antenna was an indifferent performer. Then, in order to accommodate a tribander stack, I replaced the top guys with Phillystran, and the antenna clearly and strikingly "woke up." Since the guy wire change was the only change in the near field or in the antenna itself, I think the inference is clear. 73, Pete N4ZR Check out the World HF Contest Station Database at www.pvrc.org -------------------------------------------- Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. Force12 Web Site: http://www.force12inc.com To Submit Message to the List: Force12Talk@qth.com To unsubscribe and view the Message Archive: see http://qth.com/force12/list For problems with the list: contact n4zr@qth.com -------------------------------------------- Force12Talk mailing list provided as a service by Force 12 Antennas, Inc. Force12 Web Site: http://www.force12inc.com To Submit Message to the List: Force12Talk@qth.com To unsubscribe and view the Message Archive: see http://qth.com/force12/list For problems with the list: contact n4zr@qth.com |