A forced-air cooled, fixed frequency, two cavity oscillator klystron (K3071), for operation in airborne Doppler and beacon radar equipment, has been introduced by English Electric Valve Co. The tube incorporates a heater design claimed to give a lower level of heater FM than hitherto attainable. In addition, the sturdy construction results in a tube having low noise and low microphony. A further improvement is its longer life expectancy compared with earlier types. Operating frequency of the K3071 is 8,800 ±5MHz and a typical output power is 1.5W, but variants can be supplied for operation at any frequency in the 8 to 9.5 GHZ range. Silicone rubber moulded connections are used for unpressurized high-altitude operation. English Electric Valve Co. Ltd, Chelmsford, Essex.