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25BK5
Beam Tetrode — Noval
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↗ Radiomuseum
Known Equivalents & Substitutes
No known equivalents. If you know of any, use the ⚑ Report Issue button above.
Similar Tubes (Not Drop-In Compatible)
350B
Similar beam tetrode but Octal base with 6.3V heater — different base, different heater requirements
6L6
Similar beam tetrode class but Octal base and 6.3V heater — different base and heater
Electrical Specifications
Absolute Maximum
Anode Voltage (max)
Anode Voltage (max)
250
V
Screen Voltage (max)
Screen Voltage (max)
250
V
Anode Dissipation (max)
Anode Dissipation (max)
9
W
Typical Operating
Anode Voltage (typical)
Anode Voltage (typical)
250
V
Screen Voltage (typical)
Screen Voltage (typical)
250
V
Grid 1 Bias Voltage
Grid 1 Bias Voltage (cathode bias)
5
V
Anode Current
Anode Current
35
mA
Screen Current
Screen Current
Heater
Heater Voltage
Heater Voltage
25
V
Heater Current
Heater Current
0.3
A
Notes
GE Essential Characteristics confirms: 25V/0.3A heater, Noval (9BQ) base, beam power amplifier, Pa_max=9W, Va_max=250V, Vs_max=250V.
GE data: Va=250V, Vs=250V, Vg=5V (cathode bias), Ia=35mA, Is=3.5mA, ra=100k ohms, gm=8500 umhos.
Designed for series-string heater circuits in AC/DC consumer receivers where 25V heater segments are used.
The 25V/0.3A heater is standard for the 150 mA series-string heater chain used in many AC/DC TV and radio receivers.
Pin Layout — Noval
1
2
3
4
5
6
7
8
9
1
Control Grid (g1)
2
Cathode
3
Heater
3.5
mA
Anode Resistance
Anode Resistance
100,000
Ω
Transconductance
Transconductance
8.5
mA/V
4
Heater
5
Anode (Plate)
6
No Connection
7
Screen Grid (g2)
8
No Connection
9
No Connection