Same Loctal pinout (8V) and remote-cutoff pentode, but different heater current (0.15A vs 0.3A) and different gm/rp — Raytheon lists as substitute but verify operating point
7C7
Same Loctal pinout but sharp-cutoff pentode — different grid characteristic, not suitable for AGC service
Remote-cutoff (variable-mu) pentode — grid #1 has variable pitch winding for gradual gain control.
Tung-Sol datasheet specifies two typical operating conditions: Va=300V/Vg2=100V and Va=100V/Vg2=100V.
GE lists plate current 9.2 mA and gm 2000 umhos at Va=250V, Vg2=100V; Tung-Sol datasheet shows 13 mA / 2350 umhos at Va=300V and 9.2 mA / 2000 umhos at Va=250V.
Grid #1 cutoff voltage approximately -35V.
14A7 is the 12.6V heater series equivalent (same as 12B7).
Pin Layout — Loctal
1Heater
2Plate
3Screen Grid (g2)
4
Socket-Compatible Tubes ⚠ Not electrically compatible