Sensibly equivalent¶ to:
The AC5/PenDD is a double diode output pentode with a high mutual conductance. For a local station superhet receiver the diodes provide the demodulation and the AGC voltage whilst the pentode takes the demodulated audio and directly drives the loud speaker without the need for an initial voltage amplifier stage.
The output impedance is 5,200 Ω and the cathode resistor for cathode bias is 180 Ω. The power output is given as 4.85 Watts.
Although described as a pentode it is believed that the output stage is actually a beam tetrode.
It is difficult to see tha actual construction or where the diode anodes are located.
The classic envelope is 54 mm in diameter, and excluding the B9A base pins is 125 mm tall.
References: 1040 & 1043. Type AC5/PenDD was first introduced in 1938.
Absolute Maximum Operating Conditions¶
Updated April 06, 2015.