Same Octal pinout (base 5T) but draws 3.0A filament vs 2.0A for 5R4, and lower PIV (1550V vs 2800V). Heater supply must handle the current difference.
Electrical Specifications
Absolute Maximum
Anode Voltage (max)AC Voltage per Plate (max RMS)750V
Rectifier
Peak Inverse VoltagePeak Inverse Voltage2,800V
Voltage Drop (typical)Voltage Drop (at 250 mA DC)67V
Max C-input Filter CapacitorMax C-input Filter Capacitor4µF
Notes
Directly heated (filament cathode) — observe heater warm-up time before applying B+ to protect the tube and filter capacitors.
PIV rating is current-dependent: 2800 V at 150 mA, 2400 V at 175 mA, 2100 V at 250 mA. Design must respect both PIV and current limits simultaneously.
Relatively high voltage drop (~67 V at 250 mA) compared to indirectly-heated rectifiers like 5AR4/GZ34. This limits usable output voltage but provides natural soft-start characteristics.
Maximum first filter capacitor is only 4 µF with a minimum series resistance of 250 Ω for capacitor-input filter. The 5R4GYB relaxes this to 20 µF.
The G suffix denotes glass envelope, Y denotes micanol base. 5R4GYA is the ruggedized version; 5R4GYB has higher voltage rating (900 V RMS per plate, 3000 V PIV).
Pins 4 and 6 are the two anodes (plates) for full-wave center-tapped rectification. Pins 1, 3, 5, 7 have no connection — spacing provides high-voltage insulation between plate pins and filament pins.
Pin Layout — Octal
1No Connection
2Filament
3No Connection
4
Socket-Compatible Tubes ⚠ Not electrically compatible