Tube cross-reference
1U4 alternatives, equivalents, and replacements
Review exact electrical variations and directional substitutions recorded for the 1U4 voltage pentode - sharp cutoff (single). Compare core specifications and verify every restriction before using a replacement.
Exact variations of 1U4
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.
DF904 NEW (being researched)
- Base
- Not recorded
- Socket
- Not recorded
- Base pins
- Not recorded
- Sections
- 1
- Heater voltage
- Not recorded
- Heater current
- Not recorded
Replacement tubes for 1U4
The following tubes are recorded as possible replacements for 1U4. This direction does not establish that 1U4 can replace them.
Voltage Pentode or Tetrode (under 100V)
The database records 1U4WA as a possible replacement for1U4.
No special restrictions are recorded for this substitution.
| Specification | Original tube | Replacement |
|---|---|---|
| Tube type | Voltage Pentode - Sharp Cutoff (single) | Voltage Pentode or Tetrode (under 100V) |
| Construction | Pentode | Pentode |
| Base | 6AR | 6AR |
| Socket | B7G | B7G |
| Base pins | 7 | 7 |
| Sections | 1 | 1 |
| Heater voltage | 1.4 V | 1.25 V |
| Heater current | 0.05 A | 0.05 A |
Voltage Pentode or Tetrode (under 100V)
The database records 5910 as a possible replacement for1U4.
No special restrictions are recorded for this substitution.
| Specification | Original tube | Replacement |
|---|---|---|
| Tube type | Voltage Pentode - Sharp Cutoff (single) | Voltage Pentode or Tetrode (under 100V) |
| Construction | Pentode | Pentode |
| Base | 6AR | Not recorded |
| Socket | B7G | B7G |
| Base pins | 7 | 7 |
| Sections | 1 | 1 |
| Heater voltage | 1.4 V | 1.4 V |
| Heater current | 0.05 A | 0.05 A |
Voltage Pentode - Sharp Cutoff (single)
The database records 1AF4 as a possible replacement for1U4.
- Parallel heater circuits only
| Specification | Original tube | Replacement |
|---|---|---|
| Tube type | Voltage Pentode - Sharp Cutoff (single) | Voltage Pentode - Sharp Cutoff (single) |
| Construction | Pentode | Pentode |
| Base | 6AR | 6AR |
| Socket | B7G | B7G |
| Base pins | 7 | 7 |
| Sections | 1 | 1 |
| Heater voltage | 1.4 V | 1.4 V |
| Heater current | 0.05 A | 0.025 A |
Where 1U4 can be used as the replacement
In these recorded relationships, 1U4 is the replacement tube. The listed original tubes are not automatically suitable as replacements for 1U4.
Voltage Pentode or Tetrode (under 100V)
The database records 1U4 as a possible replacement for5910.
No special restrictions are recorded for this substitution.
| Specification | 1U4 replacement | Original tube |
|---|---|---|
| Tube type | Voltage Pentode - Sharp Cutoff (single) | Voltage Pentode or Tetrode (under 100V) |
| Construction | Pentode | Pentode |
| Base | 6AR | Not recorded |
| Socket | B7G | B7G |
| Base pins | 7 | 7 |
| Sections | 1 | 1 |
| Heater voltage | 1.4 V | 1.4 V |
| Heater current | 0.05 A | 0.05 A |
Voltage Pentode - Sharp Cutoff (single)
The database records 1U4 as a possible replacement for1AF4.
- Parallel heater circuits only
| Specification | 1U4 replacement | Original tube |
|---|---|---|
| Tube type | Voltage Pentode - Sharp Cutoff (single) | Voltage Pentode - Sharp Cutoff (single) |
| Construction | Pentode | Pentode |
| Base | 6AR | 6AR |
| Socket | B7G | B7G |
| Base pins | 7 | 7 |
| Sections | 1 | 1 |
| Heater voltage | 1.4 V | 1.4 V |
| Heater current | 0.05 A | 0.025 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 1U4 specifications →