Sensibly equivalent¶ to:
The EBF89 features two signal diodes and a variable μ pentode in the one envelope and sharing a common cathode. The diode anodes are small plates placed either side of an extended cathode tube.
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. Or with a separate detector the two diodes can provide a delayed AGC voltage. This would give full amplification until a threshold is reached. The high impedance of the pentode supports the case for use with a tuned circuit connected to the anode.
The thin glass tube envelope is 20 mm in diameter and excluding the B9A base pins the valve is 57 mm tall.
References: Datasheet & 1040. Type EBF89 was first introduced in 1954.
Absolute Maximum Operating Conditions¶
Updated January 29, 2013. 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