Encyclopedia Astronautica
1974.11.15 - Oscar 7


AMSAT-OSCAR 7 was launched piggyback with ITOS-G (NOAA 4) and the Spanish INTASAT. The second phase 2 satellite (Phase II-B). Weight 28.6 kg. Octahedrally shaped 360 mm high and 424 mm in diameter. Circularly polarized canted turnstile VHF/UHF antenna system and HF dipole. Firsts: Satellite-to-satellite relay communication via AO-6; Early demonstrations of low-budget medical data relay and doppler location of ground transmitters for search-and-rescue operations were done using this satellite. AO-7 was fully operational for 6.5 years until a battery failed in mid 1981. However the satellite was still functional in day-side passes when its ever-degrading solar cells could function, and was still responding to amateurs as of August 2006.

Similar to AO-6. Built by a multi-national (German, Canadian, United States, and Australian) team of radio amateurs under the direction of AMSAT-NA. It carried Mode A (145.850-950 MHz uplink and 29.400-500 MHz downlink) and Mode B (432.180-120 MHz uplink and 145.920-980 MHz downlink (inverted)) linear transponders and 29.500 and 145.700 MHz beacons. The 2304.1 MHz was never turned on because of international treaty constraints. Four radio masts mounted at 90 degree intervals on the base and two experimental repeater systems provided store-and-forward for morse and teletype messages (Codestore) as it orbited around the world.

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