GMI-42B

Russian tube Svetlana GMI-42B is a metal-ceramic shielded-grid triode intended for use as a shunt regulator or pulse modulator in high-voltage systems. It features anode operating voltage of 33 kV and a plate dissipation of 500 watts using forced-air cooling. The GMI-42B has a shielding electrode connected internally to the cathode via short, low-impedance straps. This design permits operation with low grid current, and results in favorably low grid-anode capacitance. The presence of the ground-potential shield adjacent to the anode protects the cathode and the grid from damage due to transient arcs.
Features: extremely rugged plate currents up to 33 amps (duty cycle 0.2%)
Works in vertical position. Forced air cooling not less than 30 m³/h.

• Stamp of technical control department of the manufacturer ” ОТК “

Technical specifications:

• Voltage (AC or DC): 26 ± 2.5 V
• Current: 3.4 ± 0.25 mA
• Heating time: 3 min
• Heater-cathode voltage, peak: ±100 V
• Amplification factor (nominal): <10
• Transconductance (nominal): 400 uS
• Interelectrode capacitances (typical), with cathode grounded:
  -Input <130 pF
  -Output <25 pF
  -Feedback <2 pF

Limit Operating Values

• Anode voltage: 33 kV
• Anode dissipation: 500 W
• Cathode current, pulse (max duration 50 uS at max current): 33 A
• Grid voltage, negative: -600 V
• Grid voltage, positive (in pulse): 1.4kV
• Maximum grid dissipation: 25 W
• Seal temperature: 250 °C

Typical operation as a switch:

• Anode voltage: 2.5 kV
• Grid voltage, negative: 200 V
• Grid voltage when switched on, positive: 1.35 kV
• Pulse duration: 10 uS
• Duty factor: 0.002
• Anode current when switched on: 30 A
• Grid current when switched on: <4.5 A

Operating time not less than 2500 hours.