12J7GT

Small Signal Pentode — Octal

Known Equivalents & Substitutes

CV917

Similar Tubes (Not Drop-In Compatible)

6C6

Electrically identical predecessor but uses 6-pin UX6 base and 6.3V heater

Electrically identical but 6.3V/0.3A heater — not a drop-in in 12.6V heater circuits

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 Voltage300V

Screen Voltage (max)Max Screen Voltage125V

Anode Dissipation (max)Max Plate Dissipation0.75W

Screen Dissipation (max)Max Screen Dissipation0.1W

Heater-to-Cathode Voltage (max)Max Heater-Cathode Voltage

Section 2 — Triode Strapped

Absolute Maximum

Anode Voltage (max)Max Plate Voltage (triode)250V

Anode Dissipation (max)Max Plate Dissipation (triode)1.75W

Typical Operating

Anode Voltage (typical)Plate Voltage250V

Grid 1 Bias VoltageGrid Voltage-8V

Heater

Heater VoltageHeater Voltage12.6V

Heater CurrentHeater Current0.15A

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

1Shell and Internal Shield

2Heater

3Plate (Anode)

4

Socket-Compatible Tubes ⚠ Not electrically compatible

References