The UBF11 is a double diode pentode with a 100 mA heater. Used in domestic radio receivers for use on both AC and DC mains supplies.
The pentode section is vari μ and for use at RF, IF or AF. The double diode in the envelope points to signal demodulation and AGC voltage rectification in a superhet receiver.
The metal tube construction with a glass disc base commenced in Germany in 1938 and was originally introduced by RCA in the USA in 1935.
The wide metal tube envelope is 35 mm in diameter and, excluding the Footless base pins, is 35 mm tall.
References: Datasheet & 3002. Type UBF11 was first introduced in 1939.
Absolute Maximum Operating Conditions¶
Updated February 02, 2013. shape:wide.metal.tube construction:glass.disc type:double.diode.triode age:1930.1940 base:footless heater:100ma pins:8 pin:1.g2 pin:2.g1 pin:3.k.g3.m pin:4.a pin:5.h pin:6.h pin:7.d(1) pin:8.d(2)