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A2674

Sensibly equivalent to:
436A
    
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The A2674 is a small valve that came complete with a PTFE base. The A2674 is an M-OV valve and the 436A is from Western Electric.
At first sight the valve appears to be a triode. It took bright sunshine and a magnifying glass to see the ultra fine wire of the control grid as it passed with a minute separation in the front of the 5 mm wide flat cathode. The clue to the presence of the second grid was the obvious presence of the two sets of stout wire grid supports. This is probably of frame grid construction to achieve such a high gm figure.
The construction is typical of very high gm valves. As the anode is substantial this is probably a valve capable of some power. Putting it together suggests a wide bandwidth valve, probably a video amplifier for instrumentation use. Maybe similar to E55L. The data-sheet says it was designed for the L-3 amplifier - probably telephone use.
The wide glass tube envelope is 26 mm in diameter and, excluding the B9D base pins, is 39 mm tall.
References: Datasheet. Type A2674 was first introduced in 1963.

 

Pin Connections
B9D
1
2
3
4
5
6
7
8
9
tc

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
6.3
0.45
210
175
-1
20.0
8.2
30.0
PDF scanned from an original document held by the museum
Updated January 18, 2013.
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