AO-73 back in transponder mode

AO-73 (FUNcube-1) - Image credit Wouter Weggelaar PA3WEG

AO-73 (FUNcube-1) – Image credit Wouter Weggelaar PA3WEG

After a year long period of ‘battery management’, AMSAT-UK and AMSAT-NL have restarted the transponder on AO-73.

After 10 years in orbit, the battery on the satellite has reduced capacity and until recently, has been unable to charge to the nominal 8.3V.
Following some careful battery management, where the transmitter was off during eclipse, the battery status has improved and the transponder has been reactivated.

Although the battery voltage is varying between 8.13 in sunlight and 7.8V at the end of eclipse, this is much improved on the situation earlier in the year.

Low power BPSK telemetry is transmitted on 145.935MHz
The inverting mode U/V transponder input is 435.130 to 435.150MHz
The transponder downlink is 145.970 to 145.950MHz

At the moment the satellite has a high spin rate of apx. 30 rpm and if you’ve not used AO-73 before, the downlink can be Doppler tracked successfully, but the input on 70cms is best tuned manually due to temperature drift of the receiver.



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