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41STH

Sensibly equivalent to:
20A1 A36A AC/TH1 CV2508 TH4 X41M
    
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The 41-STH is a triode hexode frequency changer. The triode is employed as the local oscillator and the hexode as the mixer. The input RF signal is coupled to the hexode control grid via the top cap for maximum separation of the oscillator and mixer.
This frequency-changer is a very well-designed valve capable of stable operation up to at least 30 MHz.
This exhibit has the Cossor paper label and predates the exhibits with the identification printed onto the metalisation.
The B7 base and the wire connecting the external coating to the cathode pin. In this image it is clear that the circular paper cover has been lost and the wire has come away from the glass.
Thanks to Mark from Vintage-parts for sending these images.
The classic envelope is 44 mm in diameter and, excluding the B7 base pins, is 111 mm tall.
References: 1043 & 1040. Type 41STH was first introduced in 1936. See also 1936 adverts.

 

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
1.15
250
100
-1.5
3.0
4.0
1.6
0.6

 

Absolute Maximum Operating Conditions
Triode
Va
mAa
80
4.5
Updated March 20, 2017.
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