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38

Sensibly equivalent to:
CV712
    
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The Type 38 is an audio output pentode designed for car radio use and operation on a 6.3 Volt DC supply.
The load should be 10,000 Ω and the power obtained is 2.5 Watts. The figures come from Thrower, the Cunningham data-sheet has different operating parameters.
The Tone Master brand is most probably a re-seller.
Circular cathode tube and three wire grids.
Looking up into the blackened anode the ciccular grids can be seen. Below one can see that one side of the heater is open circuit in this exhibit.
The anode is stitched along the flanges and this clampes the thin sheet to the supports.
The classic envelope is 38 mm in diameter, and excluding the base pins is 97 mm tall.
References: Datasheet, & 1043. Type 38 was first introduced in 1936.

 

Pin Connections
UX5
1
2
3
4
5
tc
h
a
g2
k
h
g1

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
6.3
0.3
250
250
-25
22.0
3.8
100,000
1.2
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated September 13, 2013.
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