JC,
The issue with "at the feedpoint" vs. Force 12's specifications
which call for 100' of coax is LOSS. Loss in the coax, even 1 dB
in 100' for RG-213 at 28 MHz, causes the apparent SWR and SWR
bandwidth to be significantly better than it really is.
An antenna system with feedline loss of 3 dB (100' of RG-58 on
10 meters) will never show a SWR worse than 3:1 - no matter how
bad the antenna really is.
73,
... Joe, W4TV
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com] On Behalf Of JC Smith
> Sent: Sunday, September 03, 2006 2:36 PM
> To: n8de@thepoint.net; 'N2TK, Tony'
> Cc: 'Ron Feutz'; towertalk@contesting.com
> Subject: Re: [TowerTalk] C31 - 1 feed line or 3
>
>
> Just out of curiosity, how do you make those measurements at
> the antenna
> without your body affecting the results? On many antennas it
> is almost
> impossible to position yourself at the feed point anyway, and
> in any case,
> isn't it the whole system (antenna, support, feed line, etc.)
> we are really
> concerned with? Who cares where an antenna with no feed line
> resonates
> (other than the theoreticians). Not a criticism of your
> comment, Don, I
> believe you are correct in what you say, but what does it really mean?
>
> 73 - JC, K0HPS
>
>
>
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com]On Behalf Of Don Havlicek
> Sent: Thursday, August 31, 2006 8:24 PM
> To: N2TK, Tony
> Cc: 'Ron Feutz'; towertalk@contesting.com
> Subject: Re: [TowerTalk] C31 - 1 feed line or 3
>
> Where did you make those measurements?
>
> If at the shack end of the coax, they are quite meaningless as to
> antenna resonance.
>
> The only way to get the correct measurements is AT THE ANTENNA.
>
> Sorry, but too many guys/gals put their SWR meters at the shack end of
> the coax and try to determine what the ANTENNA looks like from there.
>
> It just doesn't work that way.
>
> Don
> N8DE
>
> N2TK, Tony wrote:
> > Ron,
> > Mine resonates at
> >
> > 28.64 - 1.1:1
> > 21.22 - 1.25:1
> > 14.1 - 1.2:1
> >
> > Single feed.
> >
> > N2TK, Tony
> >
> >
> > -----Original Message-----
> > From: towertalk-bounces@contesting.com
> > [mailto:towertalk-bounces@contesting.com]On Behalf Of Ron Feutz
> > Sent: Friday, September 01, 2006 10:02 AM
> > To: towertalk@contesting.com
> > Subject: [TowerTalk] C31 - 1 feed line or 3
> >
> > TT'ers,
> >
> > I just ordered an F12 C31XR. I have been told by experienced users
> > that the beam can be a pain to tune properly on 15 (high swr).
> >
> > I ordered the beam with single feed. Since then I have heard that
> > the problem is less severe with the 3 feedline model.
> >
> > All inputs from experienced users will be welcomed.
> >
> > Thanks and 73,
> >
> > Ron KK9K
> >
> > _______________________________________________
> >
> >
> >
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> >
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> >
>
>
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