I have a C4-XL/D on 40M it is the same antenna.
Are you using a balum?
You tune the center freq by adjusting the liner-loading wires. The
hairpin match is adjusted for a 50 ohm match. I dipped my antenna at
the freq that I wanted for a center and then used the hairpin for a 50
ohm match.
Paul
WG0G/W2
______________________________ Reply Separator _________________________________
Subject: [TowerTalk] bad coax? and EF-240 tuning
Author: leewells@lexmark.com at SMTPLINK-rammob
To: <towertalk@contesting.com>
Date: 10/15/97 2:06 PM
I'm having a little trouble getting the elements for my Force-12 EF-240
tuned up properly. I hauled the driver element up the tower yesterday
to check out the resonant frequency, and found two suprises...the
resonant freq was much higher than expected (7.300) , and the SWR was 2:1 at the
dip.
So I lowered the element back to ground level, checked it again and the
resonant freq had shifted up by about 50 Khz (sounds okay). But then
I changed feedlines (RG-8X), and the freq was down to 7.115 (closer to expected)
but the SWR is still around 2:1.
The original coax is 9913F (about 150-160 feet), its brand new, never
been on the air or outside. The second coax is some old RG-8X that is
about 40-50 feet long.
A couple questions:
1) Should the 40 Meter element have a dip of 1:1????? If so I've got some
work to do on that element.
2) How do I figure out if my coax is bad??? Would a bad connector installation
cause what I'm seeing (maybe the dielectric got too warm and the center
conductor
migrated too close to the shield?)
Thanks & 73's
--Lee - KT4ZX
Georgetown, KY
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