6DM4

Diode — Octal

Tung-Sol

Known Equivalents & Substitutes

6DM4A

Similar Tubes (Not Drop-In Compatible)

6AS4

Radiomuseum lists as normally replaceable-slightly different — same base, verify pin-for-pin compatibility

Same Octal base and active pin functions (JEDEC 4CG family) but lower PIV (4400V) and different ratings

Same Octal base and JEDEC 4CG pinout but lower ratings (PIV 4400V vs 5000V, Ia 155mA vs 175mA, Pa 5.5W vs 6.5W)

Same Octal base and pinout, similar damper diode — verify ratings before substitution

Electrical Specifications

Absolute Maximum

Anode Dissipation (max)Plate Dissipation (max)6.5W

Heater-to-Cathode Voltage (max)Peak Heater-Cathode Voltage (heater negative)5,000V

Rectifier

Peak Inverse VoltagePeak Inverse Plate Voltage5,000V

Voltage Drop (typical)Tube Voltage Drop (at 400 mA, approximate)35V

Notes

Short intermediate-shell 5-pin Octal base with external barriers (B5-82 or B5-85 / B6-60), basing diagram JEDEC 4CG. Outline drawing JEDEC 9-44.
Except for heater characteristics and heater warm-up time, the 6DM4 is identical to the 12DM4 and 17DM4.
PIV rating of 5000V applies for a 525-line, 30-frame TV system where the duty cycle of the voltage pulse does not exceed 15% of one horizontal scanning cycle (10 µs).
Maximum peak heater-cathode voltage: 5000V (heater negative, DC component max 900V) / 300V (heater positive, DC component max 100V).
Socket terminals 1, 2, 4, and 6 should not be used.
Voltage drop of 35V at 400mA is higher than many Compactron/Novar dampers (e.g. 6BJ3 at 21V, 6CJ3 at 25V), reflecting the older design.

Pin Layout — Octal

1Internal Connection

2Internal Connection

3Cathode

5Plate

Socket-Compatible Tubes ⚠ Not electrically compatible

References

DC Output Current (max)DC Plate Current (max)175mA

Peak Anode Current (surge)Peak Plate Current1,100mA

Heater

Heater VoltageHeater Voltage6.3V

Heater CurrentHeater Current1.2A

Heater

8Heater