The R9729 is a Q Band klystron complete with frequency adjustment and waveguide output. Q Band is 33 - 50 GHz. The image shows a yellow plastic plug in the waveguide end to keep dust etc from entering the cavity.
It is believed that this type of klystron dates to the late 1950s. The R9518 is very similar physically.
The IO base with adjustment shaft and waveguide and flange to the right.
The frequency adjustment; the fine thread on the shaft pulls or pushes on the threaded hexagon bar and that in turn moves a black plate that links to the top of the case. The physical length alteration of the cavity is minute.
The serial number is 4400 and the makers label says made in Great Britain. The external tuning mechanism components can be seen on the right. The bright circle is the base of the adjustment shaft.
The top of tuning mechanism.
The wide metal tube envelope is 35 mm in diameter, and excluding the IO base pins is 114 mm tall.
Updated June 01, 2013.