Tube cross-reference
U31 alternatives, equivalents, and replacements
Review exact electrical variations and directional substitutions recorded for the U31 rectifier - half wave. Compare core specifications and verify every restriction before using a replacement.
Replacement tubes for U31
The following tubes are recorded as possible replacements for U31. This direction does not establish that U31 can replace them.
Rectifier - Half Wave
The database records 25Z4GT as a possible replacement forU31.
No special restrictions are recorded for this substitution.
| Specification | Original tube | Replacement |
|---|---|---|
| Tube type | Rectifier - Half Wave | Rectifier - Half Wave |
| Construction | Rectifier | Rectifier |
| Base | Not recorded | Not recorded |
| Socket | IO | Not recorded |
| Base pins | Not recorded | Not recorded |
| Sections | 1 | 1 |
| Heater voltage | 26 V | 25 V |
| Heater current | 0.3 A | 0.3 A |
Where U31 can be used as the replacement
In these recorded relationships, U31 is the replacement tube. The listed original tubes are not automatically suitable as replacements for U31.
Rectifier - Half Wave
The database records U31 as a possible replacement for25Z4GT.
No special restrictions are recorded for this substitution.
| Specification | U31 replacement | Original tube |
|---|---|---|
| Tube type | Rectifier - Half Wave | Rectifier - Half Wave |
| Construction | Rectifier | Rectifier |
| Base | Not recorded | Not recorded |
| Socket | IO | Not recorded |
| Base pins | Not recorded | Not recorded |
| Sections | 1 | 1 |
| Heater voltage | 26 V | 25 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 U31 specifications →