Hi Jamie,
Note that the Mag 340/620 precedes the introduction of the "N"
elements.
I would guess this antenna has the old design, using support wires to
the center of the element as the linear loading, which in very
difficult modeling, and anecdotal material, does not have the
avoidance of the 15m detuning conundrum that the "N" elements have.
I do not know if later 340/620's could be bought with N elements.
What style 40 meter elements does yours have?
73, Guy.
----- Original Message -----
From: "James C. Hall, MD" <nwtncc@iswt.com>
To: "Mel Martin" <ve2dc@rac.ca>; <towertalk@contesting.com>
Sent: Saturday, April 27, 2002 3:11 PM
Subject: RE: [Towertalk] F12 40M antenna near 10-20M antennas
> 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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