Details
New old stock 9 pin miniature power amplifier pentode. EL86 is the European designation. Various brands.
NSN/FSN = 5960000873086, 5960001228841, 5960008584292, 5960009003009
HP/Agilent Number = 1923-0044, 1923-0068
Tektronix Number = 154-0202-00