[amsat-bb] Antenna separation on crossboom

[Mark D. Johns]

On Fri, Dec 14, 2018 at 10:58 AM Bob Hammond <propgrinder at gmail.com>
wrote:

>> Do you use polarity switches on your yagis?  If you do, is it worth
the effort?

No and no.

I had polarity switching on long yagis back in AO-10 & AO-13 days and it
was helpful. But for the LEO satellites we have now, it's rare to have a
fade so deep that one can't copy.
--
Mark D. Johns
KØJM / MØGZO / ex-9H3DJ / ex-KØMDJ
Brooklyn Park, MN USA   EN35hd
-----------------------------------------------
"Heaven goes by favor; if it went by merit,
   you would stay out and your dog would go in."
    ---Mark Twain



Greg,
>
>
> 73s,
>
> Bob
> W7OTJ
>
> On Mon, Nov 26, 2018 at 10:08 AM Greg D <ko6th.greg at gmail.com> wrote:
>
> > That's pretty much what I did, though with different antennas.  Also put
> > the AO-40 dish on the other side of the rotor from the 23cm helix, so it
> > went 70cm, 2.4gig, rotor, 23cm, 2m.   Put things as far away from each
> > other as you can, without running out of crossboom.
> >
> > I was very concerned about having the 70cm beam (uplink) so close -
> > inches - to the 2.4 ghz dish (downlink), but it was fine.  Good input
> > filtering in the 2.4 ghz Khune preamp, I guess.  More recently, Mode L/v
> > on AO-92 seems ok too, with the 23cm antenna near the 2m, but I have a
> > lot less power on 23cm than I did with AO-40 on 70cm.
> >
> > Greg  KO6TH
> >
> >
> > Bob Hammond wrote:
> > > I'm putting the following antennas on an 8-foot fiberglass crossboom:
> > >
> > > M2 2MCP8A, 143-148 MHz C{
> > > Gulf Alpha 70cm 8x8 CP
> > > WiMo Helix 23
> > >
> > > I'm not sure how to calculate the proper spacing on the crossboom.  I
> > > assume the 2m antenna should go on one end and the 70cm antenna on the
> > > opposite end.  Can I mount the 23cm helical antenna very near the
> rotator
> > > without harm since it has the solid reflector behind the helix?
> > >
> > > Bob
> > > W7OTJ
> > > (was WL7CQX)
> > > _______________________________________________
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> of
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> >
> _______________________________________________
> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
> to all interested persons worldwide without requiring membership. Opinions
> expressed
> are solely those of the author, and do not reflect the official views of
> AMSAT-NA.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
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