Electrically identical but 12.6V heater — not a drop-in in 6.3V circuits
6X4WA
Ruggedised 6X4 — pin-compatible but different maximum ratings (not altitude-qualified like 6202)
Electrical Specifications
Absolute Maximum
Anode Voltage (max)AC Plate-Supply Voltage per Plate (max RMS, choke-input)450V
Heater-to-Cathode Voltage (max)Heater-to-Cathode Voltage (max, heater negative)450V
Rectifier
Peak Inverse VoltagePeak Inverse Voltage (altitudes ≤ 40,000 ft)1,250V
Voltage Drop (typical)Tube Voltage Drop (at 50 mA per plate)22
Notes
Industrial/high-reliability variant of the 6X4 with tightened ratings and altitude qualification (to 60,000 ft). The 6202 is a direct replacement for the 6X4 in ordinary service.
DC output current is altitude-derated: ~55 mA max total DC output per rectifier_reference.json (down from 70 mA on the 6X4) to accommodate reduced cooling and voltage-breakdown margin at altitude.
Heater-cathode voltage limits are asymmetric: +100 V (heater positive) / 450 V (heater negative) — matters for elevated heater supplies.
Peak inverse voltage rating drops from 1250 V at altitudes ≤ 40,000 ft to 850 V above 40,000 ft due to socket/voltage-breakdown concerns at reduced pressure.
Common-cathode topology (single shared cathode on pin 7) — not suitable for voltage-doubler use.
Vdrop 22 V measured at 50 mA per plate (choke-input, per Tung-Sol 1963 datasheet).
Pin Layout — B7G
1Plate 2 (Anode 2)
2No Connection
3Heater
4
Socket-Compatible Tubes ⚠ Not electrically compatible