Tube cross-reference
6939 alternatives, equivalents, and replacements
Review exact electrical variations and directional substitutions recorded for the 6939 power - pentode (not beam). Compare core specifications and verify every restriction before using a replacement.
Exact variations of 6939
These designations belong to the same electrical variation group. Their names may differ because of international standards, manufacturing tolerances, or materials, but they are recorded as electrically equivalent—not merely substitutes.
QQE025 Voltage Dual Tetrode
- Base
- Not recorded
- Socket
- B9A
- Base pins
- 9
- Sections
- 2
- Heater voltage
- 6.3 V
- Heater current
- 0.6 A
Replacement tubes for 6939
The following tubes are recorded as possible replacements for 6939. This direction does not establish that 6939 can replace them.
Voltage Dual Tetrode
The database records 7645 as a possible replacement for6939.
No special restrictions are recorded for this substitution.
| Specification | Original tube | Replacement |
|---|---|---|
| Tube type | Power - Pentode (NOT beam) | Voltage Dual Tetrode |
| Construction | Pentode-Rectifier | Tetrode-Tetrode |
| Base | 9HL | Not recorded |
| Socket | B9A | B9A |
| Base pins | 9 | Not recorded |
| Sections | 2 | 2 |
| Heater voltage | 12.6 V | 6.3 V |
| Heater current | 0.3 A | 0.6 A |
Where 6939 can be used as the replacement
In these recorded relationships, 6939 is the replacement tube. The listed original tubes are not automatically suitable as replacements for 6939.
Voltage Dual Tetrode
The database records 6939 as a possible replacement for7645.
No special restrictions are recorded for this substitution.
| Specification | 6939 replacement | Original tube |
|---|---|---|
| Tube type | Power - Pentode (NOT beam) | Voltage Dual Tetrode |
| Construction | Pentode-Rectifier | Tetrode-Tetrode |
| Base | 9HL | Not recorded |
| Socket | B9A | B9A |
| Base pins | 9 | Not recorded |
| Sections | 2 | 2 |
| Heater voltage | 12.6 V | 6.3 V |
| Heater current | 0.3 A | 0.6 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 6939 specifications →