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12J7GT — Small Signal Pentode, Octal | Tubeofile
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12J7GT
Small Signal Pentode — Octal
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Known Equivalents & Substitutes
CV917
Similar Tubes (Not Drop-In Compatible)
6C6
Electrically identical predecessor but uses 6-pin UX6 base and 6.3V heater
6J7
Electrically identical but 6.3V/0.3A heater — not a drop-in in 12.6V heater circuits
6SJ7
Successor with identical electricals but control grid moved from top cap to pin 4 and 6.3V heater — different pin topology and heater
Electrical Specifications
Section 1 — Pentode
Absolute Maximum
Anode Voltage (max)
Max Plate Voltage
300
V
Screen Voltage (max)
Max Screen Voltage
125
V
Anode Dissipation (max)
Max Plate Dissipation
0.75
W
Screen Dissipation (max)
Max Screen Dissipation
0.1
W
Heater-to-Cathode Voltage (max)
Max Heater-Cathode Voltage
Section 2 — Triode Strapped
Absolute Maximum
Anode Voltage (max)
Max Plate Voltage (triode)
250
V
Anode Dissipation (max)
Max Plate Dissipation (triode)
1.75
W
Typical Operating
Anode Voltage (typical)
Plate Voltage
250
V
Grid 1 Bias Voltage
Grid Voltage
-8
V
Heater
Heater Voltage
Heater Voltage
12.6
V
Heater Current
Heater Current
0.15
A
Notes
12.6V heater version of the 6J7. Heater current is 0.15A at 12.6V (vs 0.3A at 6.3V for the 6J7).
Raytheon data confirms: 12.6V/0.15A heater, pentode design, Va=250V, Vg=-3V, Vs=100V, Ia=2.0mA, gm=1225 umhos, ra=1.5 MOhm.
The control grid (g1) is brought out to a top cap, not to a base pin.
Brans Vademecum lists CV917 as equivalent.
The grid circuit DC resistance should not exceed 1.0 megohm under rated maximum conditions.
Pin Layout — Octal
1
2
3
4
5
6
7
8
1
Shell and Internal Shield
2
Heater
3
Plate (Anode)
4
Socket-Compatible Tubes
⚠ Not electrically compatible
6J7
References
https://frank.pocnet.net/sheets/093/6/6J7.pdf
90
V
Max Grid Resistor
Max Grid Resistor
1
MΩ
Typical Operating
Anode Voltage (typical)
Plate Voltage
250
V
Screen Voltage (typical)
Screen Voltage
100
V
Grid 1 Bias Voltage
Grid Voltage
-3
V
Anode Current
Plate Current
2
mA
Screen Current
Screen Current
0.5
mA
Anode Resistance
Plate Resistance
1,000,000
Ω
Transconductance
Transconductance
1.225
mA/V
Capacitances
Grid-to-Plate Capacitance
Grid-to-Plate Capacitance
0.005
pF
Grid-to-Cathode Capacitance
Input Capacitance
7
pF
Anode-to-Cathode Capacitance
Output Capacitance
12
pF
other
Grid Voltage (cutoff)
Grid Voltage (cutoff)
-7
V
Anode Current
Plate Current
6.5
mA
Anode Resistance
Plate Resistance
10,500
Ω
Transconductance
Transconductance
1.9
mA/V
Amplification Factor (μ)
Amplification Factor
20
—
Capacitances
Grid-to-Plate Capacitance
Grid-to-Plate Capacitance (triode)
2
pF
Grid-to-Cathode Capacitance
Input Capacitance (triode)
5
pF
Anode-to-Cathode Capacitance
Output Capacitance (triode)
14
pF
Screen Grid
5
Suppressor Grid
6
No Connection
7
Heater
8
Cathode
TC
Top Cap —
Control Grid