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388A

Sensibly equivalent to:
CV2637 D-159769
    
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The Western Electric doorknob triode valve is of an all glass construction with the support rods protruding through the envelope and forming the connections. The filament, connected to base pins, is of a relatively thick wire, and is tensioned by a spring. The anode is a solid triangular wedge with a circular channel for the electrodes. The anode is held to pins top and bottom. The grid is a fine wire helix, and is also held top and bottom. The construction of this UHF triode was so that it could be mounted within a half-wave resonant line.
The filament rating (1.5V at 9 Amps) is unusual, to say the least. However, although the maximum anode dissipation rating is 50 Watts, (corresponding to the normal input power rating of 100 mA at 500 V DC) we are fairly sure that these valves could not deliver anything like 50 W of RF output. About 6 Watts is realistic at 700 MHz although at lower frequencies (say, 300 MHz) one would expect rather more.
See also TS1 and 316A.
The balloon envelope is 40 mm in diameter and, tip to tip is 58 mm tall.
References: Private communication & 3002.

 

Pin Connections
1
2
3
4
g1
a
f
f

 

Updated January 04, 2013.
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