The GS-3A beam-power tetrode amplifies RF power. It is rated at 3KW anode dissipation through 800MHz. It is physically large, and is well suited for amateur radio high power linear amplifiers through 432MHz! The design for a water cooling jacket is HERE.

GENERAL
Cathode:  indirectly heated, oxide-coated.
Envelope:  metal-ceramic.
Cooling:  forced water.
Height, at most (mm):	128
Diameter, at most (mm):	91
Mass, at most (gm):	800

OPERATING ENVIRONMENTAL CONDITIONS
Vibration loads:
frequency, Hz	1-200
acceleration, m/s²	59
Multiple impacts:
acceleration, m/s²	392
impact duration, ms	10
Ambient temperature, °C	- 60 to +70
Relative humidity at +35 °C,%	98

BASIC DATA Electrical Parameters
Heater voltage (AC or DC). V	26
Heater current, A	3.1-3.8
Mutual conductance (at anode voltage 1500 V, grid 2 voltage 600 V, grid 1 voltage change - 10 V and anode current 1.5 A), mA/V	30-50
Gain coefficient (grid i -gna 2) (at anode voltage 2,000 V, grid 2 voltage 500 V, grid 2 voltage change 50 V and anode current 1 A)	8-13
Output power (at anode voltage 2,500 V, grid 2 voltage 500 V. anode current 2 A, driving power 250 V, wavelength 50 cm), kW, at least	2.2
Interelectrode capacitance, pF:
input	26-34
output, at most	0.07
transfer	17-23

Limit Operating Values
Heater voltage (AC or DC), V	23.4-27.3
Heater starting current, A	5.6
Anode voltage (DC), kV	2.7
Grid 2 voltage, V	700
Driving power, W	300
Dissipation, W:
anode	3x103
grid 1	30
grid 2	60
Anode current (DC component), A	2.6
Warm up time, s	120
Operating frequency, MHz	300-800
Anode temperature, °C	110
Temperature of cathode and grids, °C	150

Averaged Anode-Grid Characteristic Curves, U1=26 V, Ua=2.5 KV

Averaged Anode-Grid Characteristic Curves, U1=26 V, Ua=2.5 KV