Fifty years ago, from March 9-27, 1965, the first two-way amateur satellite, OSCAR III, was in operation. The 16.3 kg spacecraft was launched on March 9 from Vandenberg Air Force Base, piggybacking with seven Air Force satellites. Over 1000 amateurs in 22 countries made contact through the satellite’s linear transponder, with both the uplink and downlink taking place on the 2 meter amateur band. Signals were received by the satellite on 144.1 MHz, and were retransmitted on 145.9 MHz. The downlink had a power of one watt, which was divided over the whatever stations were in the passband of the uplink frequency.

A beacon transmitter sending voltage and temperature readings was audible for several months. The orbit was nearly circular, with an altitude of 570 statute miles and an orbital period of 103.5 minutes.

The photo here shows Ed Hilton, W6VKP, and Don Norgaard, W6VMH, working on the satellite’s electronic package in Hilton’s garage. This photo is taken from the March, 1965, issue of Popular Electronics.  A summary of the mission and complete list of contacts made and calls heard during the spacecraft’s 250 orbits is also available online.