The TP23 is a battery triode pentode self oscillating frequency changer. The design use was for broadcast bands and low short waves up to 20 MHz.
The B7 base.
Thanks to Mark Mallison for sending the images.
The classic envelope is mm in diameter, and excluding the B7 base pins is mm tall.
References: Datasheet, 1040 & 1043. Type TP23 was first introduced in 1937.
Absolute Maximum Operating Conditions¶
Updated October 12, 2019. shape:classic construction:pinch type:triode.pentode age:1930.1940 base:b7 heater:2.0v pins:7 pin:1.a(t) pin:2.g1(t).g3(p) pin:3.g2 pin:4.f pin:5.f pin:6.m pin:7.a(p) pin:tc.g1(p)