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[TowerTalk] Force12 6M question

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Subject: [TowerTalk] Force12 6M question
From: "Gary - N3JPU" <>
Date: Fri, 29 Dec 2006 17:58:00 -0500
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Anyone out there using a Force12 6M antenna, especially the EF-906? 

It's a classic OWA design and I modeled it using YW and it does compare to
F12's published spec's.

50.000MHz | 12.71dBi | F/B 24.46dB | 1.07SWR | 49.4 +j 3.2
50.200MHz | 12.66dBi | F/B 22.70dB | 1.06SWR | 52.6 +j 1.1
50.400MHz | 12.58dBi | F/B 20.97dB | 1.13SWR | 53.3 -j 5.4

The boom is 30' with no truss, 2" OD with .125" wall. I'm not crazy about
the U-bolts for the elements mounts (and boom to mast mount) being plated vs
stainless. How well do these parts hold up? Other than that it's a very
robust antenna compared to others I have looked at.

I've read Cebik's several articles on OWA yagis for VHF and they appeal to
me, yes the wide band-width is over kill on 6M weak signal but I have had
problems in the past with other antennas that detune in rain, snow and ice.

A concern I have is that I have been told by another EF-906 user that he
could not get it to tune anywhere close to the weak signal portion of the
band which it is designed for. I assume Force12 is a pretty reputable
antenna manufacturer and models and range test their designs?

Gary Mitchelson
N3JPU Montgomery Co. MD  FM19


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