The 6DQ5  (P/N 154-0317-00) is a beam power pentode vacuum tube with an octal base. The plate connection is a top cap.

It is used in the Armstrong power oscillator of the 560.

Some instruments using part 6DQ5

Instrument Manufacturer Class Model Description Introduced
560 Tektronix Oscilloscope 560 1 MHz scope 1961

Links