Details
New old stock 9 pin miniature triode pentode. Various brands. "A" has controlled heater warmup time.
NSN/FSN = 5960006154745, 5960008391530, 5960005932557, 5960008344045, 5960005488384, 5960006828627, 5960005818685 (Selected Pair)
HP/Agilent Number = 1933-0002,1933-0010, 1933-0011
Tektronix Number = 154-0095-00, 157-0039-00 (Selected Pair)