Tube cross-reference
20D4 alternatives, equivalents, and replacements
Review exact electrical variations and directional substitutions recorded for the 20D4 voltage - triode (with diode, heptode or hexode). Compare core specifications and verify every restriction before using a replacement.
Replacement tubes for 20D4
The following tubes are recorded as possible replacements for 20D4. This direction does not establish that 20D4 can replace them.
Voltage - Triode (with diode, heptode or hexode)
The database records 6AJ8 as a possible replacement for20D4.
No special restrictions are recorded for this substitution.
| Specification | Original tube | Replacement |
|---|---|---|
| Tube type | Voltage - Triode (with diode, heptode or hexode) | Voltage - Triode (with diode, heptode or hexode) |
| Construction | Heptode-Triode | Heptode-Triode |
| Base | Not recorded | E9-1 |
| Socket | B9A | B9A |
| Base pins | 9 | 9 |
| Sections | 2 | 2 |
| Heater voltage | 6.3 V | 6.3 V |
| Heater current | 0.3 A | 0.3 A |
Where 20D4 can be used as the replacement
In these recorded relationships, 20D4 is the replacement tube. The listed original tubes are not automatically suitable as replacements for 20D4.
Voltage - Triode (with diode, heptode or hexode)
The database records 20D4 as a possible replacement for6AJ8.
No special restrictions are recorded for this substitution.
| Specification | 20D4 replacement | Original tube |
|---|---|---|
| Tube type | Voltage - Triode (with diode, heptode or hexode) | Voltage - Triode (with diode, heptode or hexode) |
| Construction | Heptode-Triode | Heptode-Triode |
| Base | Not recorded | E9-1 |
| Socket | B9A | B9A |
| Base pins | 9 | 9 |
| Sections | 2 | 2 |
| Heater voltage | 6.3 V | 6.3 V |
| Heater current | 0.3 A | 0.3 A |
Verify before substituting
Matching a base or heater voltage is not enough to prove that two tubes are interchangeable. Check pin connections, heater current, maximum ratings, bias requirements, warm-up behavior, and the equipment manufacturer’s service documentation before making a substitution.
View the complete 20D4 specifications →