Series-heater (300 mA) version of the EF86. Electrically identical sections — only the heater voltage/current differs (4.5 V at 300 mA vs 6.3 V at 200 mA).
Pins 1 and 7 are internal metallic shields for hum and noise reduction — must be grounded for lowest noise performance.
Pin 2 (g3/suppressor) is internally connected to cathode; separate pin allows external connection if needed.
Vhk_max is asymmetric: 100 V (cathode positive of heater) / 50 V (cathode negative of heater).
Rg_max depends on anode dissipation: 10 MΩ for Wa < 0.2 W, 3 MΩ for Wa > 0.2 W.
Pin Layout — Noval
1Screen Grid
2Internal Shield
3Cathode
Socket-Compatible Tubes ⚠ Not electrically compatible