In a message dated 11/10/2008 6:21:21 A.M. Pacific Standard Time,
towertalk-request@contesting.com writes:
> Has anyone had any experience TUNING a 2 element Force 12 linear loaded
beam
such as the EF240 or C4SXL 40 meter section?
> I have an MFJ antenna analyzer but all I can glean from the documentation
is
that the reflector should be resonant about 100 KHz lower than the driven
element.
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,
also
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
elements?
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.
Cheers,
Steve K7LXC
TOWER TECH
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