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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 later IO based 6K7 apart from the capacitances, thus this is one of the Magic Three valves.
The lettering on the glass is damaged but the name is Dario and the term Miniwatt makes the connection to Philips.
The classic envelope is 38 mm in diameter, and excluding the UX6 base pins is 99 mm tall.
References: Data-sheet, 1040, 4055 3002, & 1043. Type 78 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
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated February 24, 2022.
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