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EF94 — Small Signal Pentode, B7G | Tubeofile
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EF94
Small Signal Pentode — B7G
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Mullard
↗ r-type.org
↗ TDSL
↗ Radiomuseum
Known Equivalents & Substitutes
6AU6
6AU6A
6136
6J4P
CV2524
Similar Tubes (Not Drop-In Compatible)
3AU6
Related type with different heater ratings — not pin-for-pin equivalent
HF94
Related type with 12.6V heater — not pin-for-pin equivalent due to different heater voltage
XF94
Related type with different heater ratings — not pin-for-pin equivalent
Electrical Specifications
Section 1 — Pentode
Absolute Maximum
Anode Voltage (max)
Anode Voltage (max)
300
V
Screen Voltage (max)
Screen Voltage (max)
300
V
Anode Dissipation (max)
Anode Dissipation (max)
3.2
W
Screen Dissipation (max)
Screen Dissipation (max)
0.65
W
Notes
Suppressor grid (g3) is internally connected to cathode.
HF94 (12.6 V heater) and XF94/3AU6 (different heater ratings) are related types but not pin-for-pin equivalents due to different heater voltages.
Triode-strapped data sourced from Tom Schlangen's 'Pentodes Strapped as Triodes' (2009) measurements, not from the manufacturer datasheet.
Vhk_max is 100 V DC (cathode positive relative to heater); some 6AU6A variants are rated to 200 V.
Pin Layout — B7G
1
2
3
4
5
6
7
1
Control Grid
2
Suppressor Grid (g3
,
internally connected to cathode)
3
Heater
Socket-Compatible Tubes
⚠ Not electrically compatible
6BA6
EF91
HF94
XF94
References
https://frank.pocnet.net/sheets/020/6/6AU6.pdf
https://frank.pocnet.net/sheets/093/6/6AU6A.pdf
Cathode Current (max)
Cathode Current (max)
20
mA
Heater-to-Cathode Voltage (max)
Heater-to-Cathode Voltage (max)
100
V
Max Grid Resistor
Max Grid Resistor
1
MΩ
Typical Operating
Anode Voltage (typical)
Anode Voltage
250
V
Screen Voltage (typical)
Screen Voltage
150
V
Grid 1 Bias Voltage
Grid 1 Bias Voltage
-1
V
Anode Current
Anode Current
10.8
mA
Screen Current
Screen Current
3
mA
Anode Resistance
Anode Resistance
1,000,000
Ω
Transconductance
Transconductance
5.2
mA/V
Capacitances
Grid-to-Plate Capacitance
Grid-to-Plate Capacitance
0.004
pF
Input Capacitance
Input Capacitance
5.5
pF
Output Capacitance
Output Capacitance
5
pF
Section 2 — Triode Strapped
Absolute Maximum
Anode Voltage (max)
Anode Voltage (max)
150
V
Anode Dissipation (max)
Anode Dissipation (max)
3
W
Cathode Current (max)
Cathode Current (max)
20
mA
Typical Operating
Anode Resistance
Anode Resistance
7,500
Ω
Transconductance
Transconductance
4.8
mA/V
Amplification Factor (μ)
Amplification Factor (μ)
36
—
Heater
Heater Voltage
Heater Voltage
6.3
V
Heater Current
Heater Current
0.3
A
4
Heater
5
Anode
6
Screen Grid
7
Cathode