Tube cross-reference
6F21 alternatives, equivalents, and replacements
Review exact electrical variations and directional substitutions recorded for the 6F21 voltage pentode - remote cutoff (single). Compare core specifications and verify every restriction before using a replacement.
Replacement tubes for 6F21
The following tubes are recorded as possible replacements for 6F21. This direction does not establish that 6F21 can replace them.
Voltage Pentode - Remote Cutoff (single)
The database records 6CQ6 as a possible replacement for6F21.
No special restrictions are recorded for this substitution.
| Specification | Original tube | Replacement |
|---|---|---|
| Tube type | Voltage Pentode - Remote Cutoff (single) | Voltage Pentode - Remote Cutoff (single) |
| Construction | Pentode | Pentode |
| Base | B7G | 7DB |
| Socket | B7G | B7G |
| Base pins | 7 | 7 |
| Sections | 1 | 1 |
| Heater voltage | 6.3 V | 6.3 V |
| Heater current | 0.2 A | 0.2 A |
Where 6F21 can be used as the replacement
In these recorded relationships, 6F21 is the replacement tube. The listed original tubes are not automatically suitable as replacements for 6F21.
Voltage Pentode - Remote Cutoff (single)
The database records 6F21 as a possible replacement for6065.
No special restrictions are recorded for this substitution.
| Specification | 6F21 replacement | Original tube |
|---|---|---|
| Tube type | Voltage Pentode - Remote Cutoff (single) | Voltage Pentode - Remote Cutoff (single) |
| Construction | Pentode | Pentode |
| Base | B7G | 7DB |
| Socket | B7G | B7G |
| Base pins | 7 | 7 |
| Sections | 1 | 1 |
| Heater voltage | 6.3 V | 6.3 V |
| Heater current | 0.2 A | 0.3 A |
Voltage Pentode - Remote Cutoff (single)
The database records 6F21 as a possible replacement for6CQ6.
No special restrictions are recorded for this substitution.
| Specification | 6F21 replacement | Original tube |
|---|---|---|
| Tube type | Voltage Pentode - Remote Cutoff (single) | Voltage Pentode - Remote Cutoff (single) |
| Construction | Pentode | Pentode |
| Base | B7G | 7DB |
| Socket | B7G | B7G |
| Base pins | 7 | 7 |
| Sections | 1 | 1 |
| Heater voltage | 6.3 V | 6.3 V |
| Heater current | 0.2 A | 0.2 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 6F21 specifications →