[Top] [All Lists]

Re: [TowerTalk] [Force 12 Talk] Force 12 80M Sigma vertical problem

To: Tower Talk List <>
Subject: Re: [TowerTalk] [Force 12 Talk] Force 12 80M Sigma vertical problem
From: Gary and Kathleen Pearse <>
Date: Thu, 20 Nov 2008 14:29:59 -0900
List-post: <">>
If you've not already done so, I'd first try to isolate the feedpoint  
with a good current Balun (choke), like from DX Engineering. The  
antenna may be using the coax as part of the antenna. But then I'm  
not an engineer either.

73 Gary NL7Y

On Nov 20, 2008, at 2:23 PM, wrote:

> Howdy --
>     I recently installed a Force 12 80M Sigma.  It's like an H on  
> it's side
> and fed asymmetrically which means the feed is  off-set so you can  
> reach it
> from the ground. It's a shortened antenna so  it's got big loading  
> coils at the
> feedpoint.
>     I got the antenna to resonate at the proper  frequency (3.775  
> or so) with
> decent SWR (1.3 or so to 1). But as soon as I  hook up some coax to  
> it, the
> resonance goes up 75 kHz or so and the SWR goes to  over 3:1. I  
> tried 2 coaxes
> - 50-75 feet of RG-8X and RG-8. It seems like  the coax is  
> transforming
> something but I don't have any idea what's going on or  how to fix  
> it. Any ideas are
> appreciated. Help!
>     We're going to contact F12 but don't think they'll  be able to  
> help since
> the new owner is not an antenna engineer, did not design  the  
> antenna and
> probably doesn't have any hands-on experience with the  antenna.
> Cheers,
> Steve    K7LXC

TowerTalk mailing list

<Prev in Thread] Current Thread [Next in Thread>