UU4

Rectifier — B4

Mazda

Known Equivalents & Substitutes

No known equivalents. If you know of any, use the ⚑ Report Issue button above.

Similar Tubes (Not Drop-In Compatible)

Same B4 base and pinout but higher voltage rating (500V max vs 350V) — UU5 can replace UU4 but not vice versa

UU6

Listed as equivalent in Brans — MO base, different pinout, not a drop-in

V41

Listed as equivalent in Brans

Electrical Specifications

Absolute Maximum

Anode Voltage (max)Anode Voltage RMS per plate (max)350V

Rectifier

Peak Inverse VoltagePeak Inverse Voltage (derived: 2 × Vrms × √2)990V

Max C-input Filter CapacitorMax Reservoir Capacitor (C-input filter)8µF

DC Output Current (max)DC Output Current (max, both anodes)120mA

Heater

Heater VoltageHeater Voltage4V

Heater CurrentHeater Current2.3A

Notes

Valve Equivalents database confirms: double diode (full-wave rectifier), B4 base, 4V heater.
Brans Vademecum lists UU6 and V41 as equivalents. UU6 uses MO base — not pin-compatible.
Same heater voltage as UU5 (4V) — the UU4 is distinguished by its lower maximum anode voltage rating (350V vs 500V), not by heater differences.
Indirectly heated cathode — one side of the heater is internally connected to the cathode.
The UU5 can be used as a replacement for the UU4 (higher ratings are always safe downward), but the UU4 must not be used in UU5 circuits that exceed 350V RMS.

Pin Layout — B4

1Anode 1

2Anode 2

3Heater and Cathode

4Heater

Socket-Compatible Tubes ⚠ Not electrically compatible

References