Anode Voltage (max)AC Voltage per Plate (max RMS)450V
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.
Electrically identical to 5U4G and 5Z3 but NOT pin-compatible. The 5X4 has plates on pins 3 and 5, filaments on pins 7 and 8; the 5U4G has plates on pins 4 and 6, filaments on pins 2 and 8. The 5Z3 uses a 4-pin UX4 base. Socket wiring must be changed to substitute between these types.
Only produced in ST (shoulder) glass envelope — all specimens are effectively 5X4G. There is no metal or GT variant.
Primarily used by Zenith; RCA radios of the same era used the pin-compatible 5U4G instead.
Relatively high voltage drop (~58 V at 225 mA) compared to indirectly-heated rectifiers like 5AR4/GZ34 (~15 V). This provides natural 'soft start' characteristics valued in audio equipment.
Pin Layout — Octal
1No Connection
2No Connection
3Anode 1 (Plate 1)
4
Socket-Compatible Tubes ⚠ Not electrically compatible