The interaction mentioned affects ANY 15 meter beam, be it monobander,
tribander, 5-bander, Force 12, Cushcraft, whatever brand.. The problem
relates to whether or not the 40 meter beam has secondary resonances
close enough to 21 MHz to detune the 15 meter beam, which it will if the
resonance is close enough. Even when the beam is turned at right angles,
interaction may still remain or even be worse, due to the BOOM of the 40
meter antenna being resonant on 15, or possibly other bands.
It is related to the familiar ability to use a 40 meter dipole on 15
meters at low SWR
The question is whether or not the 402CD will detune the 15 meter beam,
not the other way around. If you already own the 402CD, there's no point
in asking. Get your tribander of choice and prepare to possibly operate
them at right angles, where the 402CD has been reported to work well.
The newer XM240 has had conflicting reports in this regard, without any
resolution that I have seen, apparently due to something in the newer
element mounting system.
The Force 12 x40N model 40 meter beams have their secondary resonance
at 18 MHz due to the design of the linear loading and are spaced with
C31's at distances as small as 8 feet, and inline.
There is considerable posting in the archives on the interaction
Apex, NC, USA
----- Original Message -----
From: "Douglas A. McDuff" <email@example.com>
Sent: Sunday, April 22, 2001 10:11 AM
Subject: [TowerTalk] C31XR / CC 402CD Question
> Before placing my order for a 31XR, I would like to know (direct email
> please) of any TT'ers experience who has/is utilizing the above
> combination. In particular, I am interested in your experience with
> interaction, degradation, etc.
> For reference, the setup here would involve the 402CD mounted 11ft
> the 31XR.
> TIA & 73, Doug W4OX
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