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.
The electrodes within the balloon envelope are held in place only at the pinch. The later classic envelope version PT4D uses the shoulder of the envelope to hold a mica disc and thus the electrodes are held at the top as well as the base.
The balloon envelope is 56 mm in diameter and, excluding the B7 base pins, is 124 mm tall.
References: Datasheet & 1043. Type PT4D was first introduced in 1934.
Absolute Maximum Operating Conditions¶
Updated March 05, 2015.