The complete waveguide distribution system splitter and phase shifter assemblies were built up and and a full set of tests were made prior to painting and shipping to STFC.  A remote factory unit was rented to accommodate all the parts - some 7 metres square in area was required.

The picture shows the complete assembly with most of the Q-par staff fitting comfortably inside where the accelerator ring will eventually stand.

The input is at the top right and the 19 cable outputs to the accelerators cavities can clearly be seen.

Testing was carried out with one of our Vector Network Analyzers and all results were extracted by computer for subsequent processing and presentation.

The hybrid coupling amplitudes around the ring were set to achieve an output amplitude  balance of better than +/- 0.36 dB at all phase shift positions.  The cables were trimmed in length to produce cophase outputs at the centre frequency (1.3 GHz) to within +/- 3 degrees, then the phase shifters trimmed to give an output phase balance of better than +/- 0.25 degrees.

One reason for using hybrid couplers to split off the power is that they will ensure a high level of isolation between cavities.  At least 40 dB was achieved without adjustment, and well in excess of 50 dB when the relevant hybrid was optimised.

Prior to assembly all parts were 100 % tested and tuned for best performance.  This strategy was well worthwhile:  the measured system input return loss was 30 dB or better, a very commendable figure given the number of components involved.

The RF precision of the work required special calibration standards to be made, consisting of short circuits, lines and tuned loads.

This picture shows the standards built for the waveguide and coaxial line (7/8 IEC) tests.