Ampera
GM70
Triode · DHT · Special · 1960
“Russian transmitting. Enormous.”
Power triode delivering 125W for push-pull and SET designs
Datasheet ↗SPICE
GAIN FACTOR0
PLATE IMPEDANCE0kΩ
TRANSCONDUCTANCE0mA/V
Cgk0pF
Cgp0pF
Cpk0pF
GAIN12%
POWER100%
DRIVE97%
LINEARITY94%
TYPICAL OPERATING POINT
EXECUTIVE SUMMARY
The GM70 is a Russian directly-heated transmitting triode with a thoriated-tungsten filament, capable of delivering 20-30W in single-ended Class A at plate voltages of 800-1200V. It is the Soviet equivalent of the Western 211/845 family, with a characteristically bold, fast, and slightly lean sonic signature. The graphite plate construction gives it high plate dissipation capability and a distinctive visual appearance. The GM70 has become popular in high-end SET designs, particularly from Chinese and Japanese manufacturers, as a cost-effective alternative to NOS Western transmitting triodes.
APPLICATIONS
SET outputPush-pull output
Generic triode transmitting (set) stage
• PA/public address
HISTORY
Introduced1960ManufacturerRussianEquivalentsGK-71 (triode)
Late ProductionSPECIFICATIONS
Heater Voltage20V
Heater Current2.4A
Max Plate Voltage2000V
Max Power125W
Sensitivity4 mA/V
Gain Factor12
Internal Impedance3.0kΩ
PinoutSpecial
Era1960
RarityModerate
Input Capacitance10pF
Miller Capacitance14pF
Output Capacitance8pF
