[Towertalk] 40m beams-fullsize 3 ele

Mon, 08 Apr 2002 02:59:53

Since no ones mentioned this one I will - the M2 full size 3 ele 40.
I don't think it's on their website, but they make them, including a 100 and 
a 125mph windspeed version.

I have the lastest Cushcraft 2 ele (XMS whatever) at 105 feet. It truly 
amazed me - 40 went from my weakest to my strongest band! Then last summer I 
put up a fullsize M2 3 ele at 140 feet - it IS bordering on a monster, and 
was a massive project (I live on Tall Pines Road - I played chainsaw instead 
of fishing most of the summer).

results?? Most of the time, NO comparison, night and day. The fullsize is 
usually about "2 S-units" better to EU, and often even better in different 
directions. I tend to leave the 3 ele on EU and use the 2 ele Cushcraft in 
other directions as it turns MUCH faster. I turn the 3 ele only if the 
pileup is too big, or after EU closes (and I have worked EU with it at high 
noon local in Nov and Dec).

Oh, you'll probably need a prop pitch, and I'd recommmend Rohn 55 star guyed 
:) One winter, only one medium/big ice storm, and all OK so far

73
Ted KR1G

>From: "Jim White" <k4oj@tampabay.rr.com>
>Reply-To: "Jim White" <k4oj@tampabay.rr.com>
>To: <TOWERTALK@contesting.com>, <n4kg@juno.com>
>Subject: Re: [Towertalk] 40m beams
>Date: Sun, 7 Apr 2002 16:37:56 -0400
>
>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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