EF806S

Small Signal Pentode — Noval

Telefunken

Known Equivalents & Substitutes

6267Z729M8195CV40856CF8EF86EF804S

Similar Tubes (Not Drop-In Compatible)

5879

Functional substitute but B7G (7-pin) base — not Noval

CV4086

Functional substitute but B7G (7-pin) base — not Noval

Electrical Specifications

Section 1 — Pentode

Absolute Maximum

Anode Voltage (max)Anode Voltage (max)300V

Screen Voltage (max)Screen Voltage (max)200V

Anode Dissipation (max)Anode Dissipation (max)1W

Screen Dissipation (max)Screen Dissipation (max)0.2W

Notes

Electrically identical to EF86 but with tighter parameter tolerances and superior mechanical construction (vibration/shock resistance).
Pins 2 and 7 are internal metallic shields for hum and noise reduction — must be grounded for lowest noise.
Pin 8 (g3/suppressor) is internally connected to cathode.
Equivalent noise voltage: approx. 2 µV (25–10,000 Hz bandwidth) at Vb = 250 V, Ra = 100 kΩ (CCIF-Norm 1949).
Vhk_max = 100 V (cathode positive of heater only). Maximum bulb temperature: 170 °C.
Rg_max depends on anode dissipation: 10 MΩ for Wa < 0.2 W, 3 MΩ for Wa > 0.2 W, 22 MΩ if bias is from Rg1 drop only.
5879 / CV4086 are functional substitutes but use a B7G (7-pin miniature) base — not pin-compatible.
Triode connection operating data documented on Telefunken datasheet pages 2–3 with three RC-coupled amplifier configurations (Ra = 47 kΩ, 100 kΩ, 220 kΩ) at supply voltages 200–400 V. Small-signal triode characteristics (μ, gm, ra) from Tom Schlangen measurements, consistent with datasheet stage-gain data.

Pin Layout — Noval

1Screen Grid

2Internal Shield

3Cathode

Socket-Compatible Tubes ⚠ Not electrically compatible

References