Seems like some enterprising person might go out a buy two XM-240's
and put them together on a single boom long boom a la the KLM 40M4.
Once the design parameters became a known quantity, and the demand
was created, CC might be tempted to follow-up with a product.
73 de Mike, W4EF..........................................
----- Original Message -----
From: <n4kg@juno.com>
To: <TOWERTALK@contesting.com>
Sent: Sunday, April 07, 2002 5:05 PM
Subject: Re: [Towertalk] 40m beams
> A CC 3L40 seems appealing.
>
> On a 36 ft boom, 1 dB additional gain could be achieved
> with significantly higher F/B.
>
> On a 48 ft boom, 2 dB additional gain could be achieved
> with moderately higher F/B.
>
> Gain rises very slowly from 0.35 to 0.75 WL which doesn't
> justify a 4L parasistic antenna unless you want to side mount
> a 48 ft boom (or less) and need more element clearance.
>
> The best reason to go to 4 elements would be for improved
> bandwidth using dual driven elements which makes sense
> since 7000 to 7300 represents 4.3% bandwidth.
>
> I believe CC has been asked about making a 3L40
> and they appear to not be interested. Too bad.
>
> Tom N4KG
>
> On Sun, 7 Apr 2002 "Jim White" <k4oj@tampabay.rr.com> writes:
> > Every so often this topic re-surfaces...so, I will take the turn this
> > time...
> >
> > The 40-2CD works very very well...
> >
> > I really would love to see someone develope a 40-3CD or 40-4CD based
> > upon
> > it...
> >
> > It seems a simple matter but nobody has ever done it...what is the
> > "hard"
> > part of this endeavour?
> >
> > It would seem that with computer modeling everywhere many must have
> > modeled
> > the 40-2CD - whilst playing with their modeling has anyone added an
> > element
> > or two to the design?
> >
> > A true full size forty is of course a dream but - a downsized 40 is
> > more
> > realistic.
> >
> > Jim, K4OJ
> >
> >
> >
> >
> > ----- Original Message -----
> > From: <n4kg@juno.com>
> > To: <TOWERTALK@contesting.com>
> > Sent: Sunday, April 07, 2002 3:52 PM
> > Subject: Re: [Towertalk] 40m beams
> >
> >
> > > On Sun, 07 Apr 2002 14:35:16 -0400 Pete Smith
> > <n4zr@contesting.com>
> > > writes:
> > > > At 06:11 PM 4/7/02 +0000, Barry Kirkwood wrote:
> > >
> > > > >Sometimes wonder if the 40m reflector is worth the trouble and
> > > > would be interested to hear from anyone who has moved from
> > > > single element to two element combination ( or vice versa)
> > > > (ZL1DD)
> > >
> > > A 40M rotary dipole is a very effective antenna, especially
> > > when placed above 70 ft high. There is a lot of benefit to
> > > be derived from having horizontal elements (as opposed to
> > > inverted vee elements) placed high and in the clear.
> > >
> > > I worked my first 300 countries on 40M using various
> > > rotary dipoles at 80 ft. My CC 2L40 shows a perceptible
> > > gain over my other dipoles.
> > >
> > > > I made this transition, and I think Barry has a valid point.
> > > > Certainly, the jump to a rotary dipole made a big difference
> > > > in my ability to put a signal where I wanted, and the
> > > > front-to-back ratio of my EF-240S (essentially the same
> > > > as the 40 meter section of the C-4SXL) is not impressive.
> > > > (N4ZR)
> > >
> > > Here are the ELNEC results for a free space 2L Yagi design
> > > using a reflector spaced 0.15 WL behind the DE for max gain,
> > > max F/B, and minimum SWR.
> > >
> > > Max Gain 6.95 dBi
> > > F/B 6 dB
> > > Feed Z 27.4 Ohms
> > >
> > > Gain 6.12 dBi
> > > Max F/B 13 dB
> > > Feed Z 44 Ohms
> > >
> > > Gain 5.58 dBi
> > > F/B 10 dB
> > > Min SWR 51 Ohms
> > >
> > > Note the low F/B ratios for 2L reflector Yagis
> > > and the loss of gain as the feed impedance is
> > > raised to match 50 ohm coax. Maximum gain
> > > designs almost always result in a low radiation
> > > resistance at the DE which requires some sort
> > > of matching network. Most split dipole fed Yagi's
> > > have less than optimum gain which is the price
> > > you pay for a direct 50 ohm feed.
> > >
> > > Tom N4KG
> > >
> > >
> > >
> > >
> > > ________________________________________________________________
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> >
>
>
> ________________________________________________________________
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