5Z3

Rectifier — DHT — UX4

Known Equivalents & Substitutes

CV1861VT-145

Similar Tubes (Not Drop-In Compatible)

Octal-based equivalent with identical ratings and characteristics — not pin-for-pin compatible due to different base (UX4 vs Octal)

5X4G

Octal-based equivalent with identical ratings — different base type and pinout

Same UX4 base but lower current rating (125 mA vs 225 mA) and lower filament current (2.0 A vs 3.0 A)

Same UX4 base, mercury-vapour rectifier — much lower voltage drop (15 V vs 58 V) but requires controlled warm-up and has limited life

Electrical Specifications

Absolute Maximum

Anode Voltage (max)AC Voltage per Plate (max RMS)550V

Rectifier

Peak Inverse VoltagePeak Inverse Voltage1,550V

Voltage Drop (typical)Voltage Drop (at 225 mA DC)58V

Max C-input Filter CapacitorMax C-input Filter Capacitor40µF

Notes

Directly heated (filament cathode) — observe heater warm-up time before applying B+ to protect the tube and filter capacitors.
Voltage drop of 58 V at 225 mA DC per plate.
With capacitor-input filter: max 450 V RMS per plate, 225 mA DC output, 75 Ω total effective plate supply impedance per plate.
With choke-input filter: max 550 V RMS per plate, 225 mA DC output, min 3 H input choke.
When filter condensers larger than 40 µF are used, it may be necessary to add additional plate supply impedance.
The 5Z3 is the direct 4-pin predecessor to the octal 5U4G — electrically identical. Replaced by 5U4G when the industry moved to octal bases.

Pin Layout — UX4

1Anode 1 (Plate 1)

2Filament

3Anode 2 (Plate 2)

4Filament

Socket-Compatible Tubes ⚠ Not electrically compatible

References

DC Output Current (max)DC Output Current (max)225mA

Peak Anode Current (surge)Peak Plate Current (per plate)675mA

Min Series Resistance (C-input)Min Total Effective Plate Supply Impedance (C-input, per plate)75Ω

Heater

Heater VoltageHeater Voltage5V

Heater CurrentHeater Current3A