Details
New old stock 7 pin miniature beam bower tube. Various brands. 6AQ5A has a controlled heater warmup time.
NSN/FSN = 5960000234197, 5960001667673, 5960002126017, 5960005397814, 5960005431720, 5960006174919, 5960009844173
HP/Agilent Number = 1923-0018, 1923-0078
Tektronix Number = 154-0017-00