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78

Sensibly equivalent to:
78E A678 AG78 CV2544 G78 UZ-78 UZ78
See also:
The 'Magic Three' Valves
    
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The 78 and 78E are variable μ RF pentodes on the American UX6 base. 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 screen has only a small gap to allow connection to the control grid and prevent shorting out the other electrodes.
The classic envelope is 38 mm in diameter, and excluding the UX6 base pins is 98 mm tall.
References: Datasheet, 1040, 4055 3002, & 1043. Type 78 was first introduced in 1933.

 

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
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated April 04, 2014.
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