[TowerTalk] Force 12 80M Sigma vertical problem

[K7LXC at aol.com]

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
TOWER TECH 
**************One site has it all. Your email accounts, your social networks, 
and the things you love. Try the new AOL.com 
today!(http://pr.atwola.com/promoclk/100000075x1212962939x1200825291/aol?redir=http://www.aol.com/?optin=new-dp
%26icid=aolcom40vanity%26ncid=emlcntaolcom00000001)