Alan Kung, BA1DU has released the latest operating schedule for the popular amateur radio satellite HO-68
Since HO-68, also known as Xi Wang 1 (XW-1), was launched on December 15 hundreds of contacts have been made through its cross-band transponders. The 68 by 48 cm satellite weighs 60 kilograms and is in a 1200 km high Sun-synchronous orbit that enables contacts between stations over 5000 km apart using the Amateur 2 metre and 70 cm bands.
The communication payload includes a CW beacon and transponders for SSB/CW, FM and digital AX.25 packet operation. The linear transponder, used for SSB and CW working, has proved very popular. It has a bandwidth of 50 kHz which allows about 10-15 simultaneous contacts to take place and can sound like the 20 metre band.
On December 30 Mike DK3WN and Henk PA3GUO showed you could also send pictures through the SSB transponder when they carried out the first Slow Scan TV (SSTV) contact.
Due to Doppler shift the CW beacon can appear to be up to +/- 9 kHz from its nominal frequency of 435.790 MHz and you need to tune your receiver to follow it during the pass. The beacon has been received on simple antennas such as a ¼ wave ground plane but for best results try a small yagi with about 8 elements.
To reduce the effects of Doppler the SSB transponder is inverting. This means that a LSB signal on the uplink becomes a USB signal on the downlink. You don’t need much power to work through the satellite, many contacts have been made using 5 watts output. Always use the lowest power possible and ensure your downlink signal is never stronger than the beacon.
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