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2A5

Sensibly equivalent to:
CV1834
See also:
Duotron 2A5 Box
    
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The 2A5 is an audio output valve. With different heater ratings and bases the 6F6 and 42 are electrically equivalent to this 2.5 Volt pentode.
The etched lettering was almost impossible to see with the naked eye. But it clearly says made in USA 2A5.
The anode plates are formed to a cylindrical space with side flanges for fixing and additional heat dissipation.
The electrodes side view. Note that the top mica is an interferance fit to the bulb but that the lower mica is only the size it needs to be to hold the electrodes.
The wire suppressor grid shows this to be a true pentode.
The classic envelope is 44 mm in diameter, and excluding the UX6 base pins is 100 mm tall.
References: Datasheet & 1043. Type 2A5 was first introduced in 1932.

 

Pin Connections
UX6
1
2
3
4
5
6
h
a
g2
g1
k
h

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
rk
rl
Pout
2.5
1.75
250
250
-16.5
34.0
6.5
0.1M
2.2
-
7,000
3W
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated February 22, 2013.
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