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Re: [TowerTalk] C31 - 1 feed line or 3

To: <>
Subject: Re: [TowerTalk] C31 - 1 feed line or 3
From: "Larry stowell" <>
Date: Fri, 1 Sep 2006 17:29:37 -0400
List-post: <>
 I mentioned this before, my swr was fine just no bandwidth maybe 100khz. They 
sent me a package
that cost $45 and consisted of two new 15 mtr element tips for the driven 
element and two coupling
coils one each for 20 and 15mtrs. with instructions to re "dress the 20 to 10 
mtr link". It still
didn't improve the bandwidth. Mine had the extra element to boom mount for 
moving the 15 mtr driven
element for separate feed lines. About this time the SteppIR came out so I sold 

Larry K1ZW
Durham, NC

-----Original Message-----
[] On Behalf Of Jim
Sent: Friday, September 01, 2006 2:49 PM
Subject: Re: [TowerTalk] C31 - 1 feed line or 3

Using a single feed, my C-31XR resonated (measured in the shack, where my 
transmitter is) well below
21.0 MHz (209??).  N6BT suggested cutting an inch, I think he said, off the end 
of each side of the
15M driven element.
At the time, I did the math and came to the conclusion that I needed to take 
off more length to get
the resonant frequency high enough in the band.

I loosened the boom guy and rotated the room 90 degrees so the elements were 
almost vertical.  I
carried a cordless drill up the tower to the first element tip and drilled out 
the rivet holding the
last/smallest tube and removed it.  I then did the same for the other side of 
the element.  I didn't
change the lengths of any parasitic elements.

I no longer have the antenna and can't find my measurements, but my 
recollection is that it covered
from the bottom end of 15M through most, if not all, of the phone band.

Again, if I am remembering correctly, the 15M driven element has no direct, 
electrical connection to
the coax, but is capacitively coupled to the 20M driven element using a single 
feedline.  The 10M
driven element is connected to the 20M DE with two, parallel wires that I tried 
to stretch taut to
keep parallel.  If I were to put up another C-31XR, I'd probably use three feed
lines to a remote switch.   It would be interesting to try a remote switch
that can be configured to either float or ground the unused ports to see if any 

Jim N7US 



Mine resonates at

28.64 - 1.1:1
21.22 - 1.25:1
14.1 - 1.2:1

Single feed.

N2TK, Tony




I just ordered an F12 C31XR.  I have been told by experienced users that the 
beam can be a pain to
tune properly on 15 (high swr).

I ordered the beam with single feed.  Since then I have heard that the problem 
is less severe with
the 3 feedline model.

All inputs from experienced users will be welcomed.

Thanks and 73,

Ron KK9K


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