Voltage Drop (typical)Tube Voltage Drop (estimate)35V
Max DC Output Current (total, not per-anode)Max DC Output Current120mA
Notes
Half-indirectly heated cathode — a design intermediate between direct and fully indirect heating.
European 4-pin B4 base limits this to vintage British equipment.
Peak Inverse Voltage is not explicitly stated in the Marconi-Osram MU12 datasheet; PIV=990 V is derived from the standard full-wave capacitor-input relation PIV = 2 × √2 × Va_max (350 Vrms). Matches the convention used for AZ12, UU4, UU5, EZ41 in this repo.
Vdrop ≈ 35V estimated from Osram MU12/MU14 datasheet regulation curves (Vtr=2×350V, Io=120mA → Vo=340V; 4V/2.5A indirectly-heated full-wave similar class to UU4/AZ4). Pure tube drop derived from cap-input regulation minus charging losses. Source: Osram Valves MU12 datasheet.
Pin Layout — B4
1Anode 1 (Plate 1)
2Heater
3Heater
4Anode 2 (Plate 2)
Socket-Compatible Tubes ⚠ Not electrically compatible