Tube cross-reference
403B alternatives, equivalents, and replacements
Review exact electrical variations and directional substitutions recorded for the 403B voltage pentode. Compare core specifications and verify every restriction before using a replacement.
Exact variations of 403B
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.
5591 Voltage Pentode - High Frequency (single)
- Base
- E7-1
- Socket
- B7G
- Base pins
- 7
- Sections
- 1
- Heater voltage
- 6.3 V
- Heater current
- 0.15 A
Replacement tubes for 403B
The following tubes are recorded as possible replacements for 403B. This direction does not establish that 403B can replace them.
Voltage Pentode - High Frequency (single)
The database records 5591 as a possible replacement for403B.
No special restrictions are recorded for this substitution.
| Specification | Original tube | Replacement |
|---|---|---|
| Tube type | Voltage Pentode | Voltage Pentode - High Frequency (single) |
| Construction | Pentode | Pentode |
| Base | E7-1 | E7-1 |
| Socket | B7G | B7G |
| Base pins | 7 | 7 |
| Sections | 1 | 1 |
| Heater voltage | 6.3 V | 6.3 V |
| Heater current | 0.15 A | 0.15 A |
Where 403B can be used as the replacement
In these recorded relationships, 403B is the replacement tube. The listed original tubes are not automatically suitable as replacements for 403B.
Voltage Pentode - High Frequency (single)
The database records 403B as a possible replacement for5591.
No special restrictions are recorded for this substitution.
| Specification | 403B replacement | Original tube |
|---|---|---|
| Tube type | Voltage Pentode | Voltage Pentode - High Frequency (single) |
| Construction | Pentode | Pentode |
| Base | E7-1 | E7-1 |
| Socket | B7G | B7G |
| Base pins | 7 | 7 |
| Sections | 1 | 1 |
| Heater voltage | 6.3 V | 6.3 V |
| Heater current | 0.15 A | 0.15 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 403B specifications →