Data: MediumMedium quality — at least 60% of universal parameters and pins are present, but some key data is missing. Verify specific values against datasheets before critical use.
Max DC Output Current (total, not per-anode)Max DC Output Current120mA
Heater
Heater VoltageHeater Voltage
Notes
Half-indirect heating — a transitional cathode design between direct and fully indirect heating.
European B4 (4-pin) base with 4V/2A filament.
Valve Equivalents reference lists as 'Double Diode' with B4 base and 4V heater.
Used in 66 documented radio models (1936-1946) per Radiomuseum.
Also referred to as 1W4/350 in some references (Taschenbuch 1948/49).
Peak Inverse Voltage is not explicitly stated in the Mazda IW4-350 datasheet; PIV=990 V is derived from the standard full-wave capacitor-input relation PIV = 2 × √2 × Va_max (350 Vrms). Matches the convention used for AZ12, UU4, UU5, EZ41 in this repo.
Pin Layout — B4
1Anode 1
2Heater/Cathode
3Anode 2
4Heater/Cathode
Socket-Compatible Tubes ⚠ Not electrically compatible