[Towertalk] F12 40M antenna near 10-20M antennas

[James C. Hall, MD]

Hi Mel:

My experience with this issue mirrors your analysis.  I have a F12 4BA at
85' and a MAG 340/620 at 75'.  The main thing I noticed is detuning of the
15 meter band ~2 MHz low !  This I am told is due to 40-15 meter
interaction. Aside from using a tuner on 15 meters (for now), all play very
well.

Cheers !

Jamie
WB4YDL

-----Original Message-----
From: towertalk-admin@contesting.com
[mailto:towertalk-admin@contesting.com]On Behalf Of Mel Martin
Sent: Friday, April 26, 2002 3:06 PM
To: towertalk@contesting.com
Subject: [Towertalk] F12 40M antenna near 10-20M antennas


Looking for opinions on this setup.
Force 12 claims that their 2 and 3 el 40M beams (240M 340M) can be
mounted within 7' of their C31.

I modeled the Cal-Av 40M, and various 2el and 3el 40M beams within 10 ft
of a C31XR and various other 10-20M beams, (using EZNEC 3.0) and the
result always seems to be serious loss of gain and destruction of the
10-20M pattern. So I'm skeptical about this "within 7 ft" claim. OTOH, I
had a TH7 10 ft over a 3 el Hy-gain (until the Ice Storm of '98) and it
seemed to work fine.

Has anyone actually used the 240N or 340N in close proximity to a higher
frequency antenna, and how were the results?

BTW, I'm looking at the Optibeam Tribander (perhaps over a 240M)...
anyone have experience with the Optibeam antennas?

Thanks...
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