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Valve Data: GEC KT88
Announced in this October 1956 trade advert the KT88 Audio Output Valve could well and truly throw a punch or two!

A New Audio Output Valve with an anode dissipation of 35 Watts

An addition to the well tried and popular range of GEC Audio Valves, of which the KT66 has set a standard in its class the world over, the new GEC KT88 is now available to meet conditions of use requiring higher power.

Points about the KT88

  1. The KT88 is a beam pentode with aligned grids for maximum efficiency.
  2. 50 watts output is available from a pair connected in the ultra linear circuit with auto bias and an HT line voltage not exceeding 500.
  3. 100 watts output is available from a pair connected in the ultra linear circuit with fixed bias and an HT voltage not exceeding 560.
  4. 25 watts output is available from a pair triode connected aith auto bias and an HT line voltage not exceeding 500.
  5. The mutual conductance of the KT88 is 11mA/V
  6. An all-glass ring seal replaces the conventional pinch seal giving increased strength, higher rating and reduced dimensions.
  7. The valve is mounted on an international octal base and has a heater rating of 6.3 volts., 1.8 amps.

The General Electric Co. Ltd., Magnet House, Kingsway, London WC2

KT88 advert from 1956

Valve Data: KT88

KT88 Base from 1957 GEC brochure

(Data taken from GEC 1957 Valve Data sheet, which calls this valve a tetrode and lists the price as 1 2s 6d plus tax)

1.8A, 6.3V Heater
Octal base

 

ra 12,000 ohms anode impedance Pin 1 Pin 2 Pin 3 Pin 4 Pin 5 Pin 6 Pin 7 Pin 8
gm 11 mA / V conductance Shield Heater Anode Grid 2 Grid 1 No pin Heater Cathode
Va 600V max anode voltage
Vg 600V max screen voltage