The CV9933 (commercially the E83F) pentode is a special quality version of the EF83.
The valve was designed for class A audio amplification in telephone equipment where long life was very important. The audio output was 0.87 Watts and the maximum anode dissipation was 2.1 Watts.
The New logo (after 1970) and the Mullard name as well as the E83F Type designation. This exhibit was made in Holland by the parent company Philips.
Within the screen is the familiar construction of two anode plates joined by a strap. The outer suppressor grid can be seen.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 57 mm tall.
Reference: Data-sheet & Philips Pocketbook for Hams 1962.
