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AC/TH1

Sensibly equivalent to:
20A1 41STH 4THA AS4125 CV2830 MM4V TH4/A/B TH4B X41
See also:
Murphy Radio - Some Important British Valves
    
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The ACTH1 is a triode hexode frequency changer from Mazda. The triode is employed as the local oscillator and the hexode for the mixing process, the input signal being coupled to the control grid via the top cap for maximum separation of the circuits.
This frequency-changer is a very well-designed valve capable of stable operation, without oscillator pulling, up to at least 30 MHz.
The reverse is plain zinc paint.
The classic envelope is 38 mm in diameter and, excluding the B7 base pins, is 103 mm tall.
References: Datasheet & 1043. Type AC/TH1 was first introduced in 1936.

 

Pin Connections
B7
1
2
3
4
5
6
7
tc
a(t)
g1(t),g3
g2,g4
h
h
m,k
a
g1

 

Absolute Maximum Operating Conditions
Hexode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
4.0
1.3
250
100
-3
3.0
6.0
1.6
0.75

 

Absolute Maximum Operating Conditions
Triode
Va
mAa
80
4.5
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated February 19, 2015.
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