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Re: [TowerTalk] Tuning a Force 12 C4SXL or EF240 2 EL 40 meter beam

Subject: Re: [TowerTalk] Tuning a Force 12 C4SXL or EF240 2 EL 40 meter beam
Date: Thu, 20 Nov 2008 18:43:33 EST
List-post: <">>
In a message dated 11/10/2008 6:21:21 A.M. Pacific Standard Time, writes:

>  Has anyone had any experience TUNING a 2 element Force 12  linear loaded 
such as the EF240 or C4SXL 40 meter  section?

>  I have an MFJ antenna analyzer but all I can glean  from the documentation 
that the reflector should be resonant about 100  KHz lower than the driven

    Usually buried in the manual are the parasitic  element resonances. I 
think the reflector is something like 2-3%  longer.

>  Does anyone have an actual step by step procedure  for tuning this beam, 
some information regarding how height above  ground will affect it from a near
ground position?

You have to do each element individually and tune  it like a dipole. If you 
can get it 20 feet or so in the air, that should  be close enough. I like to 
use a tramline to get antennas up and down so you  can use it to also run the 
antenna up and down for tuning. I've got an article  I can send you if you want 
more tramming info. 
>  Also, has anyone tried to switch between CW and PHONE using  relays to 
lengthen /
shorten the linear loading, or simply add a stub to  the driven and reflector

F12 makes a relay box to do that. It  switches some coils in and out. Much 
faster and easier than trying to come up  with your own scheme, get the parts, 
get it working, etc. 

Steve    K7LXC

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