Headphones used with a BC-221-T Frequency Meter

Headphones used with a BC-221-T Frequency Meter

Pair of headphones that were used with the BC-221-T Frequency Meter, as part of the Kettering Satellite Tracking Group's equipment.

Geoff Perry and Derek Slater used these earphones as part of their work at the Kettering Grammar School, tracking Soviet space activity. Slater and Perry's shared interest in space led to them borrowing inexpensive equipment to teach their students how to track satellites. In the process of doing this, the Kettering Satellite Tracking Group was born - which in turn led to the discovery and announcement of a secret Soviet launch site at Plesetsk, securing the Group worldwide media attention.

The BC-221-T Frequency Mete was used alongside the Marconi CR-100/2 Communications Receiver. The BC-221 was very stable so it was set to match the satellite transmission frequency, providing a reference signal. The Marconi CR-100/2 was then tuned to this reference signal, so that in turn it was also tuned to the satellite. The BC-221 acted as a Beat Frequency Oscillator to turn an otherwise inaudible radio signal into bleeps that could be detected by the human ear - using these headphones.