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78E

Sensibly equivalent to:
78E
See also:
The 'Magic Three' Valves
    
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The 78 and 78E are variable μ RF pentodes. The characteristics presented in the lower box are for the Cossor 78E whilst the first set are for the 78.
The RCA Receiving Tube manual describes the 78 as being electrically identical to the IO based 6K7 apart from the capacitances, thus this is one of the Magic Three valves.
The outer screen hides the construction - as it is designed to do. Some details can be seen above the pinch.
The classic envelope is 37 mm in diameter, and excluding the UX6 base pins is 99 mm tall.
References: Data-sheet, 1040, 4055 & 1043. Type 78E was first introduced in 1937. See also 1937 adverts.

 

Pin Connections
UX6
1
2
3
4
5
6
tc
h
a
g2
g3
k
h
g1

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
6.3
0.3
250
100
-3.0
7.0
1.7
0.8M
1.45

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
6.3
0.3
180
75
-3.0
4.0
-
1.0M
1.10
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated March 03, 2022.
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