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Re: AO-51 V/S fun portable/mobile



Hi Andrew,

Congratulations - it is great fun working satellites with this sort of
equipment.

Your S band receive antenna shud be circular polarised to allow for the
rotation of the spacecraft's linear TX antenna. It wont matter whether it is
LHCP or RHCP tho.

Even a plain patch antenna will receive AO51 on S band at workable levels
and you don't need much in the way of antenna pointing - just three
positions during the pass. Towards it at say 45 deg of elevation on
approach. Overhead when it approaches overhead and then 45 deg again when it
is going away from you.

There will still be some  fading but it should be better than any linear
antenna.


73

Graham G3VZV

----- Original Message ----- 
From: "Andrew Glasbrenner" <glasbrenner@mindspring.com>
To: <amsat-bb@amsat.org>
Sent: Thursday, February 10, 2005 4:46 AM
Subject: [amsat-bb] AO-51 V/S fun portable/mobile


> With my satellite rotor newly broken, I decided to try some AO-51 V/S
> portable/mobile tonight for giggles. I recently acquired a nifty little
> clamp-on corner reflector for my AIDC 3733 downconverter from Bob, K5GNA.
> This little gizmo clamps to the body of the d/c and uses the original
dipole
> feed to make a small gain antenna, maybe 8-10 db or so. Powered by a small
> gel cell and fed into my FT-817 on my car dash, AO-51 was loud and clear
> once I caught up with the tracking on the downlink. I should say I was
> parked on the causeway to Green Key to take advantage of an unobstructed
> horizon to the north and south.
> Doppler is rapid, but manageable by hand, except during the center of the
> pass. AFC like the 910 would be a nice feature in a handheld or portable.
> Pointing with this setup was not very critical, but polarization made a
huge
> difference. Remember AO-51 is linear on the S band transmit, as is the
> corner reflector/dipole setup, so a big mismatch might be up to 20 db or
so.
> Just twist it like a miniature Arrow to peak the signal....Uplink was my
> under dash mounted Alinco DR-605 to a 1/4 wave 2m whip on the roof rack.
50
> watts was overkill, but there was some interference at the beginning of
the
> pass from the usual pirate/taxi/fishing boat crowd to the south.
>
> I worked:
> W7JPI
> KL7QR
> KE4AZN
> N5UXT
> and a special long haul treat...
> AA6RR in Spokane, Washington. 3650 km roughly from EL88pg to DN17!
>
> I hope this will encourage some more folks to try AO-51 on V/S. I'm sure
> looking forward to SSETI on U/S too! Tomorrow I attach the d/c and corner
> reflector to an Arrow antenna.....
>
> 73, Drew KO4MA
> ----
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----
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