This exhibit is an ECC82 made in the UK by Tungsram. Designed as audio and general purpose triodes, two independent valves exist in the envelope. An amplification factor of 17 is quoted, which is much lower than that for the pin compatible ECC83 at 100 but the current rating is higher.
In television receivers the ECC82 was used as frame and line timebase multi-vibrators, AGC circuits and driver stages. It was as multi-vibrators that faults would most often develop.
The 6C4 has almost the same rating as half of an ECC82 and is rated for RF use whereas the ECC82 is not.
The twin sections side by side.
The thin glass tube envelope is 20 mm in diameter and the length excluding the B9A base pins, is 47 mm.
References: Datasheet & 1040. Type ECC82 was first introduced in 1951.