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EBF89

Sensibly equivalent to:
6DC8 6FD12
See also:
Valves and their Habits
    
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The EBF89 features two signal diodes and a variable μ pentode in the one envelope and sharing a common cathode. This Mazda exhibit is an import and marked as Foreign.
The variable μ characteristic is indicative of a device designed to have its gain controlled by an AGC system. This places this valve in service as a final IF amplifier and detector. The high impedance of the pentode supports the case for use with a tuned circuit connected to the anode.
The screening hides almost all construction details but inspection under a glass shows the diodes to be at the top in the same way as the Mullard implementation.
The thin glass tube envelope is 21 mm in diameter and, excluding the B9A base pins, is 58 mm tall.
References: Datasheet & 1040. Type EBF89 was first introduced in 1954.

 

Pin Connections
B9A
1
2
3
4
5
6
7
8
9
g2
g1
k,s
h
h
a
a(d1)
a(d2)
g3

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
6.3
0.3
250
100
-2
9
2.7
1M
3.8
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated February 21, 2019.
shape:thin.glass.tube construction:all.glass type:double.diode.pentode age:1950.1960 base:b9a heater:6.3v pins:9 pin:1.g2 pin:2.g1 pin:3.k.s pin:4.h pin:5.h pin:6.a pin:7.a(d1) pin:8.a(d2) pin:9.g3
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