[TowerTalk] RE: Question
Guy Olinger, K2AV
k2av@contesting.com
Sun, 8 Oct 2000 15:13:26 -0400
Yes, and I am puzzled why there is not a kit or ??? from Cushcraft on
it.
- - . . . . . . - - . . . . - - . . - . .
73, Guy
k2av@contesting.com
Apex, NC, USA
--... ...-- . ... --. .-..
----- Original Message -----
From: Tyler Stewart <k3mm@ex-pressnet.com>
To: Guy Olinger, K2AV <k2av@contesting.com>; William F. Beyer Jr.
<n2wb@arrl.net>; <towertalk@contesting.com>
Sent: Sunday, October 08, 2000 12:14 PM
Subject: Re: [TowerTalk] RE: Question
> I would suspect that the problem with the XM240 could have been solved
by
> simply uninsulating the reflector. That is the only substantial
electrical
> difference between the 402CD and the XM240. That fix should be as
simple as
> putting a short jumper at the center of the reflector to the boom
>
> ----- Original Message -----
> From: "Guy Olinger, K2AV" <k2av@contesting.com>
> To: "William F. Beyer Jr." <n2wb@arrl.net>; <towertalk@contesting.com>
> Sent: Sunday, October 08, 2000 5:45 PM
> Subject: Re: [TowerTalk] RE: Question
>
>
> >
> > 15 feet might not be enough...
> >
> > The problems with 40m/tribander interaction consist almost entirely
of
> > the 40 meter antenna messing up the 15 meter section of the
tribander.
> > Whose tribander or which tribander doesn't even matter, the 40 meter
> > antenna is the problem. Modeling shows that even when the SWR
> > disturbance is improved by separation, that significant pattern
> > distortion remains on 15m (not gain, f/b and f/s).
> >
> > This occurs because the ENTIRE 40 meter antenna (including the boom)
can
> > have miscellaneous resonances, particularly on 15 meters.
> >
> > Two 40 meter 2 el yagis without this problem are the older Cushcraft
> > 402CD (NOT the XM240), and the F12 240N. The XM240, in addition to
some
> > excellent strength modifications, changed the metal to metal
> > connections, and introduced 15 meter interactions not found on the
> > 402CD.
> >
> > A local contester was not able to solve interaction between an X9
and an
> > XM240 up 15 feet, even turning the XM240 90 degrees (remember, the
boom
> > is a conductor, and the elements can act as end loading). He finally
> > sold the XM240 and is using a single element 40 parallel to the X9
boom.
> > X9 is working fine.
> >
> > Part of the equation for you may be how much SWR trouble you can
> > tolerate on 15 m. If you have automatic antenna tuning, you may not
even
> > care. If you have one of the non-automatic 8877 linears, they
respond to
> > SWR swings with grid current increases which can trip out the amp.
If
> > you run high power in contests, going up and down the band, this
might
> > be intolerable.
> >
> > Wanted to make sure you knew.
> >
> > - - . . . . . . - - . . . . - - . . - . .
> >
> > 73, Guy
> > k2av@contesting.com
> > Apex, NC, USA
> >
> >
> >
> > ----- Original Message -----
> > From: William F. Beyer Jr. <n2wb@arrl.net>
> > To: <towertalk@contesting.com>
> > Sent: Saturday, October 07, 2000 10:14 PM
> > Subject: [TowerTalk] RE: Question
> >
> >
> > >
> > >
> > > Is 14 to 15 ft. spacing OK with a Force 12 C-19XR and
> > > A C.C. XM-240.
> > >
> > > 55 and 70 FT.
> > >
> > > With the C-19 on top.
> > >
> > > Any interaction problems?
> > > --
> > >
> > > 73 & see you in the pileups!
> > > William/N2WB
> > >
> > >
> > >
> > >
> > > --
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> > >
> > >
> >
> >
> > --
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> > Problems: owner-towertalk@contesting.com
> >
>
>
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