When I was in Montana, I had an ungrounded XM240 and every time a storm
would brew up you could hear the sprarking between the element and the
boom in person and obviously on the radio. At night you could see it.
I put a ground strap on my XM240 here in Colorado and I don't have that
problem. The XM240 should have minimal interaction. Mine is 10 - 12
feet above my SteppIR.
Mike W0MU
On 4/17/2014 6:26 AM, N2TK, Tony wrote:
Wasn't there something said years ago about grounding the reflector on the
XM240 so it would work like the earlier 402CD? I can't remember if this was
intended to reduce the interaction on 15M or if you had the antenna at right
angles to a 20M beam the grounding would reduce a 20M resonance on the
XM240?
Lots of cobwebs in the belfry on this one.
73,
N2TK, Tony
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Bill
Parry
Sent: Wednesday, April 16, 2014 11:40 PM
To: 'Dave Hachadorian'; 'reflector Towertalk'
Subject: Re: [TowerTalk] CC XM240 above a big Tribander
Dave
I guess that it is all a matter of antennas and situations. I put up a XM240
at about 133 feet above a Force 12 C3E at 120 feet or about 13 feet apart.
The interaction between the two was fairly obvious and the SWR on 15 was not
good. I turned the C3E 90 degrees and the problem vanished. I had the
antennas down after a lightning strike about 4 years ago and tried it again
with the same results.
Both antennas work just fine in the current configuration. I was sure that
the 13 feet would be enough but it definitely was not.
Bill W5VX
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Dave
Hachadorian
Sent: Wednesday, April 16, 2014 8:50 PM
To: reflector Towertalk
Subject: Re: [TowerTalk] CC XM240 above a big Tribander
My XM240 is six feet above a KT-34XA. The booms are aligned. It works for
me.
After you get the antennas installed, run a f/b ratio test on the tribander.
Front-to-back ratio is easy to measure, and is the most sensitive test for
adverse interaction. Here is more info:
http://lists.contesting.com/archives//html/Towertalk/2006-08/msg00634.html
I just noticed an error in the last paragraph of that 2006 posting. The
last paragraph should read, "Sometimes just changing the length of the
40-2CD's feedline, or shorting/opening its feedline when the antenna is not
being used will solve interaction problems."
Dave Hachadorian, K6LL
Yuma, AZ
-----Original Message-----
From: Marsh Stewart
Sent: Wednesday, April 16, 2014 5:15 PM
To: towertalk@contesting.com
Subject: [TowerTalk] CC XM240 above a big Tribander
How close vertically on the same mast can a new CC XM240 be to a big
10/15/20M tribander without serious interaction?
Marsh, KA5M
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