Same damper diode family (Brans groups together) but different base and ratings
6W4GT
Same function (half-wave damper diode, 6.3V heater, Octal) with similar ratings but lower PIV (1450V vs 4400V) — verify circuit boost voltage before substituting
Electrical Specifications
Absolute Maximum
Anode Dissipation (max)Plate Dissipation (max)5W
Heater-to-Cathode Voltage (max)Heater-Cathode Voltage (max, heater negative peak)4,400V
Voltage Drop (typical)Tube Voltage Drop (at 250 mA)32V
Notes
Damper diode only — power rectifier operation is not recommended per the Tung-Sol datasheet. Do not use as a conventional power supply rectifier.
Pin 2 is an internal connection and must not be used as a tie point. Pins 1, 2, 4, and 6 shall not be used as tie points.
Pin 1 is omitted on bases BS-82, BS-85, and BS-147.
Base is JEDEC 4CG (5-pin Octal). Available in Intermediate Shell (BS-82, BS-85, BS-147) and Short Intermediate Shell (B6-60) variants.
Maximum heater-cathode voltage ratings are asymmetric: heater negative 900V DC / 4400V peak, heater positive 100V DC / 300V peak. The 4400V peak rating is critical in TV damper service where the cathode sees flyback pulses.
6AX4GTA and 6AX4GTB are improved versions with different ratings — TDSL lists them as 'different rating or performance' substitutes.
Brans Vademecum groups the 6AX4GT family with EY81, PY81, PY800, 6W4GT, 6U4GT, and many heater-voltage variants (12AX4GT, 17AX4GT, 25AX4GT).
Radiomuseum confirms: Damper diode, 4.4 kV max PIV, 137 mA max DC, 825 mA peak.
Pin Layout — Octal
2Internal Connection — Do Not Use
3Cathode
5Plate (Anode)
7Heater
8
Socket-Compatible Tubes ⚠ Not electrically compatible