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TH233

 
    
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The TH233 is a triode heptode frequency changer for 200 mA series heater chains. The TH2321 is the same basic design but with higher internal capacitancies and the older B7 base.
The reverse is plain zinc paint.
Part of the internal structure seen through the gap in the zinc paint. The dark cylinder at the top is the heptode and the grid that can be seen is of the triode oscillator section that sits below the mixer. The triode anode is left bright.
The classic envelope is 32 mm in diameter, and excluding the MO base pins is 92 mm tall.
References: Datasheet, 1040 & 1043. Type TH233 was first introduced in 1939.

 

Pin Connections
MO
1
2
3
4
5
6
7
8
tc
h
k
a
a(t)
g1(t),g3
m
g2,g4
h
g1

 

Absolute Maximum Operating Conditions
Heptode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
23
0.2
150
100
-3.0
3.0
6.0
1M
0.65
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated November 27, 2014.
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