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ECH84

Sensibly equivalent to:
6JX8
See also:
ECH84 Box
    
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The ECH84 is a low voltage triode heptode. The ECH84 was specifically designed for operation as a sync separator in negative-modulation television receivers, the dual control feature of the heptode allowing the suppression of noise that would otherwise cause sync errors.
The triode heptode could be also used as a frequency changer for medium and long wave radio receivers. The heptode has a straight characteristic that makes it suitable as AM modulator.
See also the car radio frequency changer ECH83.
Through the hole in the screen it can be seen that the triode is mounted above the heptode.
The silver spots of internal coating look to be present to suppress any gas from being released from the glass by electron bombardment. The wire running up the outside of the screen connects to the triode anode.
The thin glass tube envelope is 21 mm in diameter, and excluding the B9A base pins, is 61 mm tall.
References: Data-sheet & 1040. Type ECH84 was first introduced in 1961. See also 1961 adverts.

 

Pin Connections
B9A
1
2
3
4
5
6
7
8
9
g3
g1
k,g5,s
h
h
a
g2,g4
a(t)
g1(t)

 

Absolute Maximum Operating Conditions
Heptode
Vh
Ah
Va
Vs
Vg
mAa
mAs
gm
6.3
0.3
135
14
0
1.7
0.9
2.2

 

Absolute Maximum Operating Conditions
Triode
Va
Vg
mAa
ra
gm
50
0
3.0
13.5k
3.7
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated March 02, 2026.
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