Pin 2 is internally connected to grid 3 (suppressor) and the internal shield — must be grounded for proper operation and lowest noise.
Ri (internal resistance at g1) is approximately 1 MΩ — relevant for input impedance calculations.
μg2g1 = 70, indicating a high screen-to-grid-1 amplification factor.
Equivalent noise resistance Req = 1200 Ω at the typical operating point.
Noise resistance at 50 Mc/s: rg1(50Mc/s) = 7500 Ω.
Brimar rates Va_max at 275 V rather than 300 V (Philips); use the more conservative rating in designs requiring margin.
Triode-strapped data from Schlangen measurements: mu=70, gm=7.2 mA/V, ra=9.7 kΩ — high-mu triode characteristic suitable for high-gain voltage amplifier stages.
Pin Layout — B7G
1Control Grid (g1)
2Suppressor Grid (g3) + Internal Shield
3Heater
4
Socket-Compatible Tubes ⚠ Not electrically compatible