Designed as general purpose triodes, two independent valves exist in the ECC82 envelope. A special quality version was also produced, the E82CC. Designed for differential amplifiers in industrial equipment, the anti microphonic and matched pair version E182CC was also made.
An amplification factor of 17 is quoted, and the ECC82 is virtually a pair of EC90 triodes in a single envelope but not designed for RF use.
We were surprised at the very low CV number, suggesting availability at the start of WWII even though the B9A base is post war in the UK.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 50 mm tall.
References: Data-sheet & 1040. Type ECC82 was first introduced in 1951. See also 1951 adverts.