[TowerTalk] C31 - 1 feed line or 3

[Joe Subich, W4TV]

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 at contesting.com 
> [mailto:towertalk-bounces at contesting.com] On Behalf Of JC Smith
> Sent: Sunday, September 03, 2006 2:36 PM
> To: n8de at thepoint.net; 'N2TK, Tony'
> Cc: 'Ron Feutz'; towertalk at 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 at contesting.com
> [mailto:towertalk-bounces at contesting.com]On Behalf Of Don Havlicek
> Sent: Thursday, August 31, 2006 8:24 PM
> To: N2TK, Tony
> Cc: 'Ron Feutz'; towertalk at 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 at contesting.com
> > [mailto:towertalk-bounces at contesting.com]On Behalf Of Ron Feutz
> > Sent: Friday, September 01, 2006 10:02 AM
> > To: towertalk at 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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