[amsat-bb] SO-50's ELEVENTH Birthday!

Clint Bradford clintbradford at mac.com
Wed Dec 18 17:45:47 PST 2013

It is SO-50's ELEVENTH birthday! Read on for how YOU can celebrate!

Now known as SO-50, Saudisat 1C is a Saudi Arabian picosatellite that 
was launched by a Dnepr rocket from Baikonur at 17:00 UT on December 20, 
2002. SO-50 features a "Mode J" FM amateur repeater operating on a 2M 
uplink and a 440 downlink.

"Most hams already own the necessary equipment to work SO-50," reports 
Clint Bradford, K6LCS, who maintains a Web site devoted to working amateur 
satellites with minimal equipment (http://www.work-sat.com).

"It is preferable to work SO-50 in true, full-duplex mode - so you can hear the 
downlink as you transmit. This means - for most - using a second radio or 
the Kenwood TH-D72A and its true full-duplex capability. The new Puxing 
PX-UV973 is currently being tested in this mode, too, to see how it works on 
the satellites."

SO-50's repeater is available to amateurs worldwide, and it uses a 67.0 Hertz 
PL tone on the uplink. SO-50 also has a 10 minute timer that must be armed 
before use. If you know the satellite is there - but there is nothing heard - you 
may need to shoot it a PL tone of 74.4 to turn it ON!

The repeater consists of a miniature VHF receiver with sensitivity of -124dBm, 
with an IF bandwidth of 15 KHz. The receive antenna is a 1/4 wave vertical 
mounted in the top corner of the spacecraft. Its UHF transmitter is a mere 250 
mW, and downlink antenna is a 1/4 wave mounted in the bottom corner of the 
spacecraft and canted at 45 degrees inward.

"Hams just with Technician licenses can work the satellite," Clint continues. "We 
are talking about weak signals from 500 miles away - so improving both your 
TX and RX antennas is critical for success on this satellite." Plans for making tape 
measure beams and other inexpensive, high-gain antennas is also on his Web site.

"Do not forget to accommodate for the Doppler phenomenon on the 440 receive 

Complete details - including frequency chart and sources for knowing when the 
satellite will be over your area, are also on Clint's Web site.


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