Mullard CV4003 (M8136 / ECC82 / 12AU7 military grade) tube

Mullard CV4003 (M8136 / ECC82 / 12AU7 military grade) NOS with Mitcham factory coding.

The printed markings:

• 000-4003
• CV4003
• KQDD/K
• 85-09

The etched factory codes:

• 631
• R413

Tube type CV4003 is the British military designation for the Mullard M8136, which is a premium, military-spec version of the ECC82 / 12AU7 dual triode.