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C Band AWSOME !



As per my previous posts, I mounted the 3733 (stub cut, 123 mhz output to a
FT-847, 150 ft of RCA RG-6) with the dipole flush against the plastic cover
on my existing 10 FT, C-Band feedhorn, with the dipole vertical.  I tied it
there with dacron string.

The downconverter came off at a 90 deg angle to the axis of the feedhorn,
and was taped to one of the four feedhorn support "legs".

No physical changes were made to the position of the dish mounting.

Today, at approximately 1300Z(+), AO-40 hung around 177 deg az. and 50 deg
el., for about 60 minutes, which required only fine tuning the dish with the
remote control.

The was no comparison when AO-40 was directly in front of the dish, as
compared to the "main" system of a Parabolics AB downconverter and Phillips
36 inch dish, with computer az / el control.  I ran the two systems
simultaneously with two computers.

The C band blew it away !!!  (NOT surprising)

I was able to copy good CRC with the dish off 8 degrees in az and 15 degrees
in elevation, 1356Z.  (At this time the dish was at it's most eastern
position of about 160 az and 49 el. and at the end of the pass.)  I copied
"bad" blocks until it was off 16 deg in az and 23 deg in elevation, 1403Z.
LOS was at 1413Z. Tuesday 04-24-2001.

INTERESTING:  At times, each system copied "good" CRC blocks when the other
didn't!  Both systems have their antennas vertical, and each had
approximately equal signal strength, at the time, as compared to the S/N
ratio screen on AO40Rcv 1.22.

I would like to see a thread started here, as to what makes "good" CRC's.
Is there a difference in sound cards?  I don't have a circular polarized
antenna at the moment. I am going to build a two pound coffee can feed when
time permits. YES, I KNOW it doesn't weigh two pounds, and yes I know it is
not circular polarization.  If anyone has a  three to five turn helix they
want to get rid of, please let me know.

  This time, I did not follow doppler by manually tuning,  I let "Moe"
(AO40Rcv) do it for me as long as it stayed in the bandpass.

FWIW,   Bob
AC9R@amsat.org
Mid. TN. Coordinator
AMSAT #2001

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