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12A5

Sensibly equivalent to:
CV908
    
Extras ▼

 

The 12A5 has a conventional indirectly-heated cathode but its heater is centre-tapped so that it could be used in (American) car radios suitable for either 6V or 12V systems. Car radios of this era used 'vibrator' HT power packs which were not very suitable for generating HT voltages in the 250-300V region. The 12A5 was therefore designed to operate well from lower HT voltages and therefore needed a 'juicier' cathode to provide extra current.
The classic envelope is 37 mm in diameter and, excluding the UX7 base pins, is 90mm tall.
References: Datasheet & private communication. Type 12A5 was first introduced in 1940.

 

Pin Connections
UX7
1
2
3
4
5
6
7
h
a
g2
g1
k
hct
h

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
Pout
D
6.3
0.6
180
180
-25
48
14
35,000
2.4
3.4W
11%
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated February 16, 2013.
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