Power - Pentode Single (NOT beam) (under 10W) ·Pentode
3W4
3W4/354-SF directly heated miniature battery audio output pentode with series/parallel 2.8 V 25 mA or 1.4 V 50 mA filament and typical 0.25 W audio output.
- Sections
- 1
- Base
- 7BA
- Socket code
- -
- Base pins
- 7
- Nominal heater
- 2.8 V / 25 mA
General specifications
Tube and section characteristics
Properties common to every published source and operating point.
Heater and base
- Base
- 7BA
- Socket code
- -
- Base pins
- 7
- Nominal heater voltage
- 2.8 V
- Nominal heater current
- 25 mA
- Parallel heater voltage
- 1.4 V
- Parallel heater current
- 50 mA
- Series capable
- Yes
7BA - Terminal pinout
Electrical assignments shared by every tube using this base designation.
| Terminal | Section | Connection | Evidence |
|---|---|---|---|
| PIN1F | — | F — Filament Source EIA label F; manufacturer confirmation pending | Unverified EIA Base Connections, printed page 128, 7BA |
| PIN2P | A | P — Plate (Anode) Source EIA label P; manufacturer confirmation pending | Unverified EIA Base Connections, printed page 128, 7BA |
| PIN3G1 | A | G1 — Control Grid EIA source designation G1; manufacturer confirmation pending | Unverified EIA Base Connections, printed page 128, 7BA |
| PIN4G2 | A | G2 — Screen Grid EIA source designation G2; manufacturer confirmation pending | Unverified EIA Base Connections, printed page 128, 7BA |
| PIN5G3 | A | G3 — Suppressor GridGroup 7BA5 EIA source designation G3; manufacturer confirmation pending | Unverified EIA Base Connections, printed page 128, 7BA |
| PIN5FCT | — | FCT — Filament Center TapGroup 7BA5 EIA source designation FCT; manufacturer confirmation pending | Unverified EIA Base Connections, printed page 128, 7BA |
| PIN6P | A | P — Plate (Anode) EIA source designation P; manufacturer confirmation pending | Unverified EIA Base Connections, printed page 128, 7BA |
| PIN7F | — | F — Filament EIA source designation F; manufacturer confirmation pending | Unverified EIA Base Connections, printed page 128, 7BA |
Section ratings
1 physical section, each with unique specifications.
Section 1
Pentode
- Plate resistance
- 150000 Ω
- Transconductance
- 0.0017 S
- Max plate voltage
- 90 V
- Max screen voltage
- 90 V
- Max cathode current
- 11 mA
3W4/354-SF battery audio output pentode, design-center maximum plate voltage 90 V (first-page OCR may read 80 V, verify scan), screen grid 90 V, cathode current 11 mA. Typical Va 85 V, Vg2 85 V, Vg1 -5.2 V, rp ~150 kΩ, gm 1700 µmhos = 0.0017 A/V, zero-signal Ia 6.8 mA, Ig2 1.4 mA, load 11 kΩ, peak AF signal 5.2 V, audio output 0.25 W, THD 12%. Directly heated coated center-tapped filament, 2.8 V 25 mA series or 1.4 V 50 mA parallel. Grid3 tied to negative filament on pin1.
Source-dependent data
Operating conditions by source
Each block preserves the test conditions and published values from one reference. Values from different sources are intentionally kept separate.