[amsat-bb] Re: Mounting antennas on a tower & Don't forget the PREAMP!
kl7uw at acsalaska.net
Sat Sep 22 12:36:51 PDT 2007
Regarding mounting satellite antennas on a mast above a HF antenna:
1- If center-mounted one must set the elevation rotor high enough so
that when pointing straight up the sat antennas clear the HF antenna
2- If end-mounted, the elevation rotor can be mounted lower but this
will cause unbalanced loading of the elevation rotor. (for short Leo
antennas no problem, but if this is being designed for P3E, Eagle and
other Heos then the 2m and 70cm beams probably will have longer booms
(my KLM 22C and M2 436CP42 are 18-foot long and not designed for end-mounting).
3. If the HF beam and satellite array are rotated by the same azimuth
rotator here is a idea: Mount the satellite antennas pointed in
azimuth at right angles to the HF beam so that when elevated the
VHF/UHF antennas can rotate between the HF elements. You would not
be able to rotate elevation horizon to horizon due to the HF boom but
this would permit a lower position on the main mast (for
auto-tracking this might be a problem). In fact the satellite
antenna rear ends may project below the tower top when fully elevated
(but not below guy cables if used for tower).
73 Ed - KL7UW
At 10:16 AM 9/22/2007, John W Lee wrote:
>I Agree with Steve,
>An Arrow antenna is about as end mounted as you can get,
>and look at all the success folks have had with them.
>I've made at least 1000 QSO's with my Arrow.
>Second comment: I've seen all the traffic regarding preamps, noise
>figures, etc etc etc. And the real bottom line is this: They help you
>hear better. No doubt about it.
>On Sat, 22 Sep 2007 12:56:31 -0400 Steven Raas <sraas at optonline.net>
> > I can attest to the performance of end mount antennas! I have made
> > well over
> > 500 Sat contacts all with my end mount yagis. Photos and full
> > station
> > description avail on my website, the url is in the Signature of my
> > email.
> > Any questions please feel free!
> > 73
> > Steven J.Raas
> > QRV From FN20vg on 2/432 Terestrial-Sats-Digital-EME
> > Member of - ARRL & AMSAT
> > Supporter of N3FJP Software http://www.n3fjp.com
> > Home Page - http://n2jdq2007.tripod.com/
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