Voltage Drop (typical)Forward Voltage Drop (read from Abb. 3 I/V curve at 125 mA per plate)35V
Max DC Output Current (total, not per-anode)Max DC Output Current250
Notes
Higher heater current (2.3 A) than AZ1 (1.1 A), enabling higher rectified current capability.
European side-contact P8A base.
First documented May 1938 per Philips Bulletin.
Peak Inverse Voltage is not explicitly stated in the Telefunken/Philips AZ4 datasheet; PIV=1414 V is derived from the standard full-wave capacitor-input relation PIV = 2 × √2 × Va_max (500 Vrms). Matches the convention used for AZ12, UU4, UU5, EZ41 in this repo.
Vdrop=35 V is read from the single-plate I/V characteristic (Philips AZ4 datasheet Abb. 3, Ia per anode vs Va) at 125 mA per plate (= Idc_max 250 mA / 2 for full-wave). The datasheet does not state a discrete Vdrop value.
Pin Layout — P8A
1Anode 1 (Plate 1)
2Heater
3Anode 2 (Plate 2)
4
Socket-Compatible Tubes ⚠ Not electrically compatible