Oscar 7 (AO-07)

Launch data: Designation 07530 / 74089B Launch date 15 Nov 1974 - 17:11 UT Launch site Va, SLC-2W Launch vehicle Delta-2310 (#592/D104) Mission Civil: Amateur radio communications LEO Polar Earth orbit Perigee / Apogee  1440 x 1460 km Eccentricity  1.28E-03 Inclination  101.7 deg Period  114.9 min

Spacecraft data: Prime contractor  Amsat-NA Operator  Amsat-NA Platform   Mass at launch  28.6 kg Dry Mass   kg Basic shape  Octahedrally shaped Dimension (m)  360 mm high and 424 mm dia Solar array   Stabilization  Passive magnetic DC power  15 W (NiCd battery) Uplink (MHz)  145.850-145.950 Downlink (MHz)  29.400-29.500 Beacon (MHz)  29.502 Mode  A Call sign   Status  Active

End of life

Description:

• The second phase 2 satellite (Phase II-B). Weight 28.6 kg. Orbit 1444 x 1459 km. Inclination 101.7 degrees. Octahedrally shaped 360 mm high and 424 mm in diameter. Circularly polarized canted turnstile VHF/UHF antenna system and HF dipole.
• 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. The Mode-B transponder was designed and build by Karl Meinzer, DJ4ZC and Werner Haas, DJ5KQ. The Mode-B transponder was the first using "HELAPS" (High Efficient Linear Amplification by Parametric Synthesis) technology was developed by Dr. Karl Meinzer as part of his Ph.D.
• AMSAT-OSCAR 7 contains two basic experimental repeater packages, redundant command systems, two experimental telemetry systems, and a store-and-forward message storage unit. The spacecraft is solar powered, weighs 65 pounds, and had a three-year anticipated lifetime at the time it was launched, but it has far outlived this expectation. It contains beacons on 29.50, 145.975, 435.10 and 2304.1 MHz.

Mission details:

• AMSAT-OSCAR 7 was launched November 15, 1974 by a Delta 2310 launcher from Vandenberg Air Force Base, Lompoc, California. AO-7 was launched piggyback with ITOS-G (NOAA 4) and the Spanish INTASAT.
• AO-7 became non-operational in mid 1981 due to battery failure. In 2002 one of the shorted batteries became an open and now the spacecraft is able to run off solar panels. For this reason it is not usuable in eclipse and may not be able to supply enough power to the transmitter to keep from frequency modulating the signal.
• In January 2006 AO-7 precessed to a point where it remained completely out of eclipse until May 15, 2006. During this period AO-7 has returned to it's previous schedule of alternating between Mode A and Mode B. This period of non-eclipse will return sometime in late Autumn each year for the foreseeable future and will extend well into the Spring.

External links:

• dk3wn: Satellite Information
• Satellite tracking (n2ya.com): Real time satellite tracking