You might think a little about it. If it affects one fifteen meter beam
in-line, it will affect any because the secondary resonance effect is on
the forty meter beam, not the 15 meter beam. Also please note that the
21 MHz resonance effect uses the ENTIRE element, behaving like three
electrical half waves, not one, and since the loading coil is not a 15
meter trap, the length of the element between the coils does not control
the secondary resonance.
As to factuality, a good friend here in the Raleigh area had this
problem, and spent some serious money to have a noted east coast ham
tower man to try all the possibilities. My friend's factual wallet pain
on the issue, in my mind, trumps your postulations, as do quite some
number of posts which may be found in the archives.
I stand by my prior remarks.
I will not respond to your ungentlemanly use of "presumptuous" or
inference that I am misleading to pad some interest.
For the record, I have no financial or commercial interest in ANY of the
antenna manufacturers. I could care less who makes the worst and best,
other than to avoid the one and embrace the other. I have paid the going
price for any antenna I have bought.
Apex, NC, USA
----- Original Message -----
To: <TOWERTALK@CONTESTING.COM>; <k2av@CONTESTING.COM>
Sent: Monday, April 23, 2001 1:26 AM
Subject: Re: [TowerTalk] C31XR / CC 402CD Question
> Guy -
> I find your specification of 15M interaction to be misleading
> and presumptious. I can understand how a FULL SIZE 40M
> element would interact with 15M performance due to harmonic
> relationships but not the "shorty-forties".
> The 402CD is an Inductively LOADED 40M beam.
> The loading coils are spaced very close to 1/2 WL at 18 MHz,
> NOT 21 MHz. This is supported by the numerous reports of
> satisfactory use of the 402CD on 17M with relatively low SWR.
> The BOOM of the 402CD is roughly 20+ ft BUT the reflector is
> BOTH electrically and mechanically attached to the Boom,
> thus END loading the boom. The DE is isolated from the boom
> but the COAX surely adds some capacitive coupling between
> the boom and at least one side of the DE, further end loading
> the boom. The 24 ft boom of my 3L20 meter beam resonates
> around 7.5 MHz. Surely the 20+ ft boom of a 2L40 with 40M
> elements resonates even lower, NO WHERE NEAR 15M.
> SO, I find it hard to understand your statement that ANY
> 15M beam would be affected by the proximity of a 402CD.
> de Tom N4KG
> On Sun, 22 Apr 2001 "Guy Olinger, K2AV" <email@example.com> writes:
> > The interaction mentioned affects ANY 15 meter beam, be it
> > monobander, tribander, 5-bander, Force 12, Cushcraft, whatever
> > problem relates to whether or not the 40 meter beam has secondary
> > 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
> > 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,
> > point in asking. Get your tribander of choice and prepare to
> > operate them at right angles, where the 402CD has been reported to
> > 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
> > with C31's at distances as small as 8 feet, and inline.
> > There is considerable posting in the archives on the interaction
> > question.
> > 73.
> > -----------------
> > Guy Olinger
> > Apex, NC, USA
> > ----- Original Message -----
> > From: "Douglas A. McDuff" <firstname.lastname@example.org>
> > To: <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
> > > combination. In particular, I am interested in your experience
> > with interaction, degradation, etc.
> > >> > For reference, the setup here would involve the 402CD mounted
> > above the 31XR.
> > >
> > > TIA & 73, Doug W4OX
> > >
> > > List Sponsor: ChampionRadio.com - Trylon self-supporting towers,
> > > safety equipment, rigging gear, LOOS tension guages & more!
> > > http://www.championradio.com
> > >
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