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I have a 4BA mounted 15' above a EF-420/240 with an EF-180B in the middle aligned to boom direction. 4BA is at about at 95' from the ground and 48' above the roof. I have more or less the same situation on 12m. The resonance is placed at 24.2 MHz (swr = 1:1.1). I wrote to Natan and I sent him a wideband swr diagram; he said: <quote> "For some reason, the 12 mtr driven element seems to be too long. You can loosen the U-bolts on the boom to rotate the elements vertically. Maybe this will allow you to reach the element. Shorten each tip on the 12 mtr driver about 3". " <unquote> Unfortunately I wasn't in the position to to carry-out the modification and now we are in winter time. I will do it in the spring time. That is all so far. Merry Christmas and Happy New Year to everybody. 73 de ik2cik, Pietro -----Messaggio originale----- Da: Stephen P. Hart [mailto:k8ej@ix.netcom.com] Inviato: venerdì 22 dicembre 2000 22.21 A: Force12Talk@qth.com Oggetto: [Force 12 Talk] 4BA Problems 1.) My 4BA, mounted 12' below an EF430 (as Force 12 suggested) exhibits an SWR of 2.3-2.6 across the 12M band. Lowest SWR (1:1) occurs at 24.275Mhz. I have sent the complete SWR curves for all bands, as requested, to Force 12 & Force 12 East twice, via email over the last two months. No response. Anyone else having this SWR or lack of feedback problem? The antenna does exhibit directivity and seems to work satisfactorily. 2.) The 4BA boom has turned in the boom-to-mast clamp causing the elements to be 5-10 degrees out of horizontal. Have talked to 4 other users (most with C19 antennas) who have the same problem. Tightening the clamps further doesn't seem to be a good option so pinning the boom to the mast plate appears to be the way to go. I have concerns about weakening the boom even drilling a small hole thru it. Any suggestions? Thanks, Steve - K8EJ -------------------------------------------- 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 -------------------------------------------- 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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