Tube cross-reference
5603 alternatives, equivalents, and replacements
Review exact electrical variations and directional substitutions recorded for the 5603 power - pentode single (not beam) (under 10w). Compare core specifications and verify every restriction before using a replacement.
Replacement tubes for 5603
The following tubes are recorded as possible replacements for 5603. This direction does not establish that 5603 can replace them.
Power - Pentode Single (NOT beam) (under 10W)
The database records 398A as a possible replacement for5603.
No special restrictions are recorded for this substitution.
| Specification | Original tube | Replacement |
|---|---|---|
| Tube type | Power - Pentode Single (NOT beam) (under 10W) | Power - Pentode Single (NOT beam) (under 10W) |
| Construction | Pentode | Pentode |
| Base | B8-11 | B8-11 |
| Socket | IO | IO |
| Base pins | 8 | 8 |
| Sections | 1 | 1 |
| Heater voltage | 6.3 V | 6.5 V |
| Heater current | 0.5 A | 0.5 A |
Where 5603 can be used as the replacement
In these recorded relationships, 5603 is the replacement tube. The listed original tubes are not automatically suitable as replacements for 5603.
Power - Pentode Single (NOT beam) (under 10W)
The database records 5603 as a possible replacement for398A.
No special restrictions are recorded for this substitution.
| Specification | 5603 replacement | Original tube |
|---|---|---|
| Tube type | Power - Pentode Single (NOT beam) (under 10W) | Power - Pentode Single (NOT beam) (under 10W) |
| Construction | Pentode | Pentode |
| Base | B8-11 | B8-11 |
| Socket | IO | IO |
| Base pins | 8 | 8 |
| Sections | 1 | 1 |
| Heater voltage | 6.3 V | 6.5 V |
| Heater current | 0.5 A | 0.5 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 5603 specifications →