[amsat-bb] AO-51 Mode L/U over West Malaysia

Sion Chow Q. C. (9W2QC) 9w2qc at 9w2qc.net
Mon Oct 2 01:21:40 PDT 2006

Hello All,

This morning, 2nd October 2006 at 0945 Hours Local or 0145 Hours UTC, we had
a 72 degree pass of AO-51 over West Malaysia.  My father, Dr. Chow C. O.,
9M2CCO and I were in the shack this morning to prepare for the pass.  This
would be our first attempt to test out the L band as there are no
terrestrial activities on the L band locally to try it out.

First of all, we started with the V/U repeater after AOS.  After verifying
that we could operate it normally, we gave out a few CQ calls, but
unfortunately no one responded.  Then we moved to the L/U repeater.  My
father gave out a few CQ calls, as I could not operate on this frequency.
(just because I am reluctant to take the morse code test) 

To our surprise, with only 10 Watts of power from the ICOM IC-910H into a
16-Element Comet Yagi Antenna, gave a very clear and solid audio on the
downlink.  When the elevation was above 30 degrees, only 5 watts of power
was needed to have a very clear downlink.  However, a little more power was
needed when the elevation dropped below 30 degrees.  10 watts was more than
enough until about 5 degrees in elevation. But we have some surrounding tall
buildings in the LOS direction anyway.

To conclude our first L band test, I would say that this is a very
interesting mode, and it requires less power on the uplink as compared to
2M.  Maybe this is due to the fact that the 2M band is polluted with illegal
operations around this region.  This can be proven when AO-51 is operating
without the required PL tone.

Equipment used were ICOM IC-910H, 10-Element Yagi for 2M, 2x15-Element Yagi
for 70CM (Unfortunately no preamp for the downlink) and 16-Element Yagi for
23 CM.  All antennas are vertically polarized.  The station here was also
automatically tracking the antenna and Doppler and this made operating very

A big thank you to the command team for this very interesting mode, and will
like to see it more often in the future.  I have tested the V/S mode before,
and am now waiting to test the L/S mode in the future.

Sion Chow Q. C.,

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