The QKK1789 is a small receiver reflex klystron for the X band. We have no specific operating details for this klystron but the 723A/B is physically very similar.
The course frequency adjustment is by the mechanical system shown here. The movement of the screw thread opens or closes the gap between the metal leaves. The vertical movement is effectively geared down from the screw movement. This reduction process is continued as the top ring is held to a rod one side and operates the internal cavity bellows as a third order lever. In all a very small change in the dimension of the internal cavity results. Fine tuning is carried out electrically.
The octal base has pins missing closest to the probe. The valve holder is a modified IO socket with a clearance hole for the probe. The latter is positioned so as to penetrate the wide dimension of the associated waveguide to provide the optimal coupling of the RF to the guide.
The probe is a thin wire insulated with PTFE and housed in a metal tube. The probe is probably a quarter wave length long. Overall the probe is 32 mm long and the tip is approximately 8.5 mm long. This suggests the 9.6 GHz Radar band.
This image is of a 723A/B located within the specially modified octal valve holder that is positioned above waveguide 16. The probe is on the right.
The open end of the waveguide. Sadly this has been cut through very close to the valve holder. This process enabled the maximum length of waveguide to be re-used, but for us it is too short to mount a new flange and build a new piece of equipment.
The wide metal tube envelope is 25 mm in diameter, and excluding the IO base pins is 56 mm tall.