GU-78B

The Russian generator tetrode GU-78B (ГУ-78Б rus.) is designed to amplify high-frequency oscillations at frequencies up to 250MHz with an output power of at least 2.5kW. GU-78B is used for power amplification in amplifiers with distributed amplification and single-sideband signal.
It is produced in ceramic-metal design with an external anode and ring electrode leads.
Works in a vertical position, pins down. Forced air cooling not less than 280 m³/h.

GU – a letter that determines the type of tube: GU – generator tubes with a generation frequency of 30 to 300MHz;
78 – the number of the serial number of the development of this type of tube;
B – letter indicating the type of forced cooling: B – air.

Technical specifications:

• Heating voltage: 27V
• Glow current: 3.4 – 4.0A
• Anode voltage: 1.7kV
• Voltage of the 2nd grid: 300V
• Bias voltage of the 1st grid: – 51V
• Lock-off voltage (at Ua=3kV; la=20mA), negative: no more than 150V
• Anode current: 1.5A
• Zero anode current (at Ua=250V; Uc1=0V): not less than 4.2A
• Current of the 2nd grid zero (at Ua=250V; Uc1=0V): no more than 0.9mA
• Slope: 60 ± 20mA/V
• Output power in class AB1 mode (at Un=27V): 2.5kW
• Output power in class AB1 mode (at Un=25.7V): 2.2kW

Limiting performance:

• Heating voltage: 25.7 – 28.3V
• Anode voltage constant: 3kV
• Anode voltage (instantaneous value): 6.2kV
• Voltage of the 2nd grid constant: 350V
• Negative voltage of the 1st grid (absolute value): 150V
• Cathode current: 2.2A
• Current of the 1st grid (constant component): 25mA
• Power dissipated by the anode: 2.5 kW
• Power dissipated by the 2nd grid: 30W
• Power dissipated by the 1st grid: 1W
• Operating frequency: 250MHz
• Cathode heating time: 240 sec.
• Sheath and junction temperature: 200°С

Operating time not less than: 2000 hours.