During the tribander testing the K7LXC and I did a couple years ago (see
the Champion Radio web site for the reports...shameless plug) I noticed
that the "shock driven" or "sleeve driven element" antennas were affected
by the wind and when the antenna rotation came to an abrupt halt. The
models we tested of this design were the C31XR, C3, and Skyhawk.
The symptoms were that VSWR would vary a little bit and you could also see
forward gain going up and down (about a dB, max) for a few seconds. I
didn't test in strong winds, obviously, but did note that behavior existed
and suggested that spacers would cure it. This would only be an issue
with antennas working at 20-meters and lower frequencies due to element
length and flexibility.
I don't consider this a major problem with either antenna as the
variations that I observed were minor. It might be a problem in a really
high-wind environment - and the simple set of spacers would fix it.
Montana certainly has high average wind speed and particularly on a
200-foot tower.
Not everyone needs those spacers - just a few people with special
situations, like some need to truss or support large antennas under
certain circumstances. That Force 12 has these spacers doesn't indicate
that there's a design flaw in the antenna - rather they are providing good
customer support by having them on hand for those that need them.
I certainly wouldn't pass by the C31, C3, or Skyhawk just because of this
issue. They're all three fine antennas and performed at the top of their
class.
73, Ward N0AX
> This is not the first report of some F12 antennas needing spacers to avoid
> wind-whipping problems. I've heard of this before, from a fellow who took
> his down. He reportedly asked F12 about this, was told they haven't had a
> problem, but then was sent some spacers to alleviate the problem. The
> conclusion he drew was that if the F12 had no problems with this, how come
> they had spacers on hand to resolve the problem? I hadn't thought much about
> this with only the one report, but now there's several....I had been
> considering this antenna up until now. I am following this thread with great
> interest.
> Jerry K3MGT
>
> ----- Original Message -----
> From: EUGENE SMAR <SPELUNK.SUENO@prodigy.net>
> To: <w6ter@worldnet.att.net>; <towertalk@contesting.com>
> Sent: Tuesday, May 15, 2001 1:42 AM
> Subject: Re: [TowerTalk] Force 12 C3 spacers
>
>
> > Gerry:
> >
> > The Bencher Skyhawk had a similar problem until they came up with a
> set
> > of phenolic spacers.
> >
> > But I'm afraid they might have patented it. ;>)
> >
> > 73 de
> > Gene Smar AD3F
> > -----Original Message-----
> > From: Gerald Smith <w6ter@worldnet.att.net>
> > To: towertalk@contesting.com <towertalk@contesting.com>
To: <towertalk@contesting.com>
> > Date: Monday, May 14, 2001 8:55 PM
> > Subject: [TowerTalk] Force 12 C3 spacers
> >
> >
> > >I visited N7ML's QTH (Bozeman, MT) whereas he had six Force 12 C3's
> > >stacked on a rotating 200' tower. He found he needed spacers,
> > >non-conducting, between the driven elements tips to keep them from
> > >hitting together during high winds.
> > >
> > >Has anybody experienced this? Anybody have a spacer design?
> > >
> > >Gerry, W6TER
> > >
> > >List Sponsor: Champion Radio Products - We'll be at the Dayton
> Hamvention
> > >with all of our safety equipment and other products. Stop by booth #559
> and
> > >say hi.
> > ><A HREF="http://www.championradio.com";>www.ChampionRadio.com</A>
> > >
> > >-----
> > >FAQ on WWW: http://www.contesting.com/FAQ/towertalk
> > >Submissions: towertalk@contesting.com
> > >Administrative requests: towertalk-REQUEST@contesting.com
> > >Problems: owner-towertalk@contesting.com
> > >
> >
> >
> > List Sponsor: Champion Radio Products - We'll be at the Dayton Hamvention
> > with all of our safety equipment and other products. Stop by booth #559
> and
> > say hi.
> > <A HREF="http://www.championradio.com";>www.ChampionRadio.com</A>
> >
> > -----
> > FAQ on WWW: http://www.contesting.com/FAQ/towertalk
> > Submissions: towertalk@contesting.com
> > Administrative requests: towertalk-REQUEST@contesting.com
> > Problems: owner-towertalk@contesting.com
> >
> >
>
>
> List Sponsor: Champion Radio Products - We'll be at the Dayton Hamvention
> with all of our safety equipment and other products. Stop by booth #559 and
> say hi.
> <A HREF="http://www.championradio.com";>www.ChampionRadio.com</A>
>
> -----
> FAQ on WWW: http://www.contesting.com/FAQ/towertalk
> Submissions: towertalk@contesting.com
> Administrative requests: towertalk-REQUEST@contesting.com
> Problems: owner-towertalk@contesting.com
>
List Sponsor: Champion Radio Products - We'll be at the Dayton Hamvention
with all of our safety equipment and other products. Stop by booth #559 and
say hi.
<A HREF="http://www.championradio.com";>www.ChampionRadio.com</A>
-----
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
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Problems: owner-towertalk@contesting.com
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