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12A7

Sensibly equivalent to:
CV909
See also:
Brimarize
    
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The 12A7 is a combined audio output pentode and half wave rectifier. The pentode has an output of 550 mW and the rectifier has a rating of 30 mA. The valve is on an American UX7 base and the voltages clearly indicate that it was designed for use on American 110 Volt mains supplies. The target market seems to be local station radio receivers.
The pentode is on the left with the rectifier as a very thin assembly on the right. The heaters are connected in parallel.
Face view of the rectifier section. The base carries the RCA branding.
Thanks to Mark Mallison for sending the image.
The classic envelope is 44 mm in diameter, and excluding the UX7 base pins is 113 mm tall.
Reference: Datasheet. Type 12A7 was first introduced in 1937.

 

Pin Connections
UX7
1
2
3
4
5
6
7
tc
h
a
g2
k(d)
a(d)
k
h
g1

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
6.3
0.3
135
135
-13.5
9.0
2.5
102k

 

Absolute Maximum Operating Conditions
Rectifier
Va
mAa
125
30.0
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated February 16, 2019.
shape:classic construction:pinch type:pentode age:1940.1950 base:ux7 heater:12.6v pins:7 pin:1.h pin:2.a pin:3.g2 pin:4.k(d) pin:5.a(d) pin:6.k pin:7.h pin:tc.g1
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