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12AH8

Sensibly equivalent to:
20D3 CV5317
    
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The 12AH8 is a triode heptode frequency changer. The triode oscillator couples internally to the heptode grid number three. The design is aimed at HF communications receivers where oscillator stability is important.
The triode oscillator runs with 100 Volts on the anode to generate a 9.4 Volt LO signal. The heater is centre tapped so that either a 12.6 Volt supply across pins 4 and 5 can be used or a 6.3 Volt supply across pins 4 & 5 together and pin 9.
The heptode is the lower unit with the triode mounted above the separating mica.
The thin glass tube envelope is 21 mm in diameter, and excluding the B9A base pins is 58 mm tall.
References: Datasheet, 1040 & 1043. Type 12AH8 was first introduced in 1953.

 

Pin Connections
B9A
1
2
3
4
5
6
7
8
9
g2,g4
g1
k,g5
h
h
a
g1(t),g3
a(t)
hct

 

Absolute Maximum Operating Conditions
Heptode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
12.6
0.15
250
100
-3
2.6
4.4
1.5M
0.55
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated November 28, 2014.
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