Sensibly equivalent¶ to:
AC2/Pen/DD DDPP4B DN41
The PT4D is a directly heated double diode output pentode. The PT4 was originally designed for when a directly heated valve was required and had slightly less output than the MPT4.
The cathode resistor is given as 150 Ω and the anode load is 6,500 Ω.
Thanks to Bob Hopkins for sending the image.
The classic envelope is mm in diameter and, excluding the B7 base pins, is mm tall.
References: Datasheet & 1043. Type PT4D was first introduced in 1934.
Absolute Maximum Operating Conditions¶
Updated August 29, 2018. shape:classic construction:pinch type:double.diode.pentode age:1930.1940 base:b7 heater:4.0v pins:7 pin:1.a(d2) pin:2.a pin:3.a(d1) pin:4.h pin:5.h pin:6.k pin:7.g2 pin:tc.g1