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PM2A

Sensibly equivalent to:
220PA CV3643 LP2 P220
See also:
The Azide Process - Mullard PM2A Advert - 1931 Advert - Mullard PM2A Box - Mullard PM12, PM1HL & PM2A Advert - Mullard Valves for the Set of the Future Advert - Mullard 'Set of the Future' Advert - Mullard PM2A & PM202 Advert - Mullard 2 Volt Valves Advert - QPP with Triodes
    
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The PM2A is an early audio output valve. It is designed for battery operation and, naturally, the output power is very low. The anode load is quoted as optimum at 7,000 Ω.
The base pins are split and opened to grip the socket. Above the pince the anode can be seen to be mounted horizontally. The black inner to the envelope is a result of the mechanism of the Azide process to form an oxide emitting surface.
The The dome carries the identification.
The balloon envelope is 45 mm in diameter and, excluding the B4 base pins, is 88 mm tall.
References: 1931 data-sheet & 1043. Type PM2A was first introduced in 1930. See also 1930 adverts.

 

Pin Connections
B4
1
2
3
4
a
g1
f
f

 

Absolute Maximum Operating Conditions
Triode
Vh
Ah
Va
Vg
mAa
ra
gm
Pout
2.0
0.2
135
-6
5.0
6000
2.0
0.15
Thanks to Andy Cowley for supplying the above PDF datasheet.
Updated January 30, 2024.
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