GU-78B

TETRODE

The GU-78B tetrode is used for power amplification in distributed amplifiers and single-sideband signal amplifiers at frequencies up to 250 MHz, in RF industrial engineering equipment.

GENERAL
Cathode: indirectly heated, oxide-coated.
Envelope: metal ceramic, with ring leads of cathode, grid 2 and anode and pin leads of grid 1.
Cooling: forced air.
Height: at most 120 mm.
Diameter: at most 111 mm.
Mass: at most 1.8 kg.

BASIC DATA Electrical Parameters
Heater voltage (AC or DC), V	27
Heater current, A	3.4-4
Anode voltage, kV	1.7
Grid 2 voltage, V	300
Negative grid 1 bias voltage, V	51-25
Negative cutoff voltage (at anode voltage 3 kV, anode current 20 mA), absolute value, V	-150
Anode current, A	1.5
Anode current at zero grid 1 voltage (at anode voltage 250 V), mA, at most	4.2
Grid 2 current at zero grid 1 voltage (at anode voltage 250 V), mA, at most	0.9
Mutual conductance, mA/V	40-80
Output power under amplification of class AB1, kW:
at heater voltage 27 V, at least	2.5
at heater voltage 25.7 V, at least	2.2
Common-cathode interelectrode capacitance, pF:
input	100-150
output	15-30
transfer, at most	0.25

Limit Operating Values
Heater voltage (AC or DC), V	25.5-28.3
Anode voltage, V:
DC	3,200
instantaneous value	6,200
Grid 2 voltage (DC), V	350
Negative grid 1 voltage (DC, absolute value), V	150
Cathode-heater voltage (either polarity, absolute value), V	150
Cathode current (DC component), mA	2,200
Grid 1 current (DC component), mA	25
Dissipation, W:
anode	2,500
grid 2	30
grid 1	1
Operating frequency, MHz	250
Cathode heating time, s	240
Envelope temperature at hottest point, °C	200

Averaged Anode Characteristic Curves:
U_f = 27V; U_g2 = 300V

Averaged Characteristic Curves:
U_f = 27V; U_g2 = 300V;
_____ anode grid;
_ _ _ grid 2;
_ . _ grid 1

Averaged Grid-Anode Characteristic Curves:
U_f = 27V; U_g2 = 300V;
————— I_g2
- - - I_g1

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