Tube cross-reference
408A alternatives, equivalents, and replacements
Review exact electrical variations and directional substitutions recorded for the 408A voltage pentode - sharp cutoff (single). Compare core specifications and verify every restriction before using a replacement.
Exact variations of 408A
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.
6028 Voltage Pentode - Sharp Cutoff (single)
- Base
- E7-1
- Socket
- B7G
- Base pins
- 7
- Sections
- 1
- Heater voltage
- 20 V
- Heater current
- 0.05 A
Replacement tubes for 408A
The following tubes are recorded as possible replacements for 408A. This direction does not establish that 408A can replace them.
Voltage Pentode - Sharp Cutoff (single)
The database records 6028 as a possible replacement for408A.
No special restrictions are recorded for this substitution.
| Specification | Original tube | Replacement |
|---|---|---|
| Tube type | Voltage Pentode - Sharp Cutoff (single) | Voltage Pentode - Sharp Cutoff (single) |
| Construction | Pentode | Pentode |
| Base | 76D | E7-1 |
| Socket | B7G | B7G |
| Base pins | 7 | 7 |
| Sections | 1 | 1 |
| Heater voltage | 20 V | 20 V |
| Heater current | 0.05 A | 0.05 A |
Where 408A can be used as the replacement
In these recorded relationships, 408A is the replacement tube. The listed original tubes are not automatically suitable as replacements for 408A.
Voltage Pentode - Sharp Cutoff (single)
The database records 408A as a possible replacement for6028.
No special restrictions are recorded for this substitution.
| Specification | 408A replacement | Original tube |
|---|---|---|
| Tube type | Voltage Pentode - Sharp Cutoff (single) | Voltage Pentode - Sharp Cutoff (single) |
| Construction | Pentode | Pentode |
| Base | 76D | E7-1 |
| Socket | B7G | B7G |
| Base pins | 7 | 7 |
| Sections | 1 | 1 |
| Heater voltage | 20 V | 20 V |
| Heater current | 0.05 A | 0.05 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 408A specifications →