The filter is first tested in a pre-weld test fixture consisting of four threaded rods inserted between two waveguide-to-end cavity transitions torqued sufficiently to hold the cavities together snugly. Initial tuning and testing in this configuration is done to identify and remove by reworking any manufacturing defects detrimental to performance. Filter tuning or alignment begins using a Filter Fit analysis program [1]. This program utilizes the coupled cavity filter model used to generate the desired design parameters to find the actual parameters from the measured response. It adjusts the coupling values mathematically, via iris dimensional changes and tuning screw adjustments, until the fitted coupling values based on measured data match the desired values, the desired response is achieved and the design loop is closed [2].

After welding the cavities together to form the complete lifter only small variations in tuning usually result from the welding action so fewer fitting iterations are typically required to restore the performance obtained in the thread rod jig before welding.

At the conclusion of the post-weld test, the tuning screws are staked in placed with a silicon-based adhesive and the filter is painted. Upon completion of the required cure durations, the filter is then routed back to test for a final functional performance verification where the filter is measured to verify that the staking and painting operations did not affect tuning. Upon successful measurement, the filter is then installed on the spacecraft.