Operating point uses a positive g1 supply rail (+8 V, Philips; +9 V, Siemens) rather than connecting g1 to ground. The cathode resistor (Rk = 370 Ω) sets the actual bias: Vk ≈ 9.6 V, giving an effective Vg1-k ≈ −1.6 V. This topology allows a higher Rk for improved RF noise performance.
Pin 8 (g3, shield): NOT internally connected to cathode — must be tied to cathode externally in pentode operation. In triode connection (method A: g2 → anode, g3 → cathode) it also connects to cathode. A second triode method (g2 and g3 both to anode) is sometimes used; it increases feedback capacitance.
Both cathode pins (1 and 3) should be connected in parallel. The Siemens datasheet recommends parallel connection for lowest noise (both cathode leads connected).
When using a cathode bypass capacitor > 10 µF, the grid resistor must be at least 1 kΩ (Siemens specification).
CV10775 is the British military equivalent designation.
7722 is the CBS-Hytron (US) equivalent designation — identical tube, different trade name.
D3a (Siemens) shares the same Noval pinout and is the closest Western equivalent by application, but has significantly higher gm (35 mA/V) and μg2g1 (80). E180F and E186F share the same pinout with lower gm.
S/C ratio (transconductance-to-capacitance) = 2.2 mA/V/pF; gain-bandwidth figure S/2πCges = 180 MHz (Cges = Ce + Ca + 5 pF stray capacitance).
Pin Layout — Noval
1Cathode
2Control Grid (g1)
3Cathode (connected to pin 1)
Socket-Compatible Tubes ⚠ Not electrically compatible