GU-78 B


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.


gu-78 b


OPERATING ENVIRONMENTAL CONDITIONS

Vibration loads:

frequencies, Hz 1-60
acceleration, m/s2 20
Multiple impacts with acceleration, m/s2 150
Ambient temperature, œC -60 to +70
Relative humidity at up to +25 œC without moisture condensation, % 98


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, œC 200


gu-78 b


Averaged Anode Characteristic Curves:
Uf = 27V; Ug2 = 300V


gu-78 b


Averaged Characteristic Curves:
Uf = 27V; Ug2 = 300V;
_____ anode grid;
_ _ _ grid 2;
_ . _ grid 1


gu-78 b


Averaged Grid-Anode Characteristic Curves:
Uf = 27V; Ug2 = 300V;
----- Ig2
- - - Ig1


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