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7HG8

Sensibly equivalent to:
PCF86
    
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The 7HG8 is a triode pentode VHF TV frequency changer and was made in the UK. The triode is the oscillator and the pentode is the mixer. The pentode is of frame-grid construction.
This triode pentode was made in a number of different heater configurations: 4HG8 - 4.5 V @ 0.6A, 5HG8 - 5.3 V @ 0.45 A, 6HG8 - 6.3 V @ 0.34 A (same as ECF86), 7HG8 - 7.2 V @ 0.3 A (same as PCF86) and 8HG8 - 8.0 V @ 0.3 A.
Other data sources give the 7HG8 a heater rating of 8 Volts at 300 mA the same as the PCF86.
The triode has holes in the ends of the anode and the grid can be seen. The anode of the pentode obscures the internal electrodes.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 48 mm tall.
References: Datasheet, 3002 & 1040. Type 7HG8 was first introduced in 1960.

 

Pin Connections
B9A
1
2
3
4
5
6
7
8
9
k,g3,s
g1
k,g3,s
h
h
g1(t)
a(t)
a
g2

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
8.0
0.3
190
140
-1.5
8.5
2.7
0.35M
4.5

 

Absolute Maximum Operating Conditions
Triode
Va
mAa
120
6.0
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated January 29, 2013.
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