THERMIONIC TRIODE FOR VHF OPERATION, THE VERY FIRST ACORN TUBE IN MASS PRODUCTION
955 'acorn'
The type 955 triode "acorn tube" is a small triode thermionic valve (vacuum tube in USA) designed primarily to operate at high frequency. Although data books specify an upper limit of 400–600 MHz, some circuits may obtain gain up to about 900 MHz.
Kosmos 955 (; International Designator: 1977-091A, satcat number 10362) was a Soviet ELINT satellite, launched from the Plesetsk Cosmodrome on September 20, 1977, at 01:01 UTC. The satellite's mass was 2,500 kg.