Shawyer Cavity Build – Aluminum Lathed


The machined cavity was created in order to eliminate flexing and match the cavity much closer to the simulated one, both problems with the previous plastic cavity.


The inside profile from CST MWS simulator was imported into the 3D modeling software and then revolved to create the final circular shape. A probe mounting ring was added to mount the probes flush (figure 2). In the figure 2, it is recessed on purpose because to get it flush, the rounded surface was sanded down.

The cost was roughly $700 for the aluminum, about $800 for the machining, $300 for copper plating and $280 for shipping. After five months, which included a few weeks dealing with Canadian customs, the cavity arrived as shown in figure 3.

The first attempt at attaching the probes used solder, but the thin copper plating could not hold the probes upright. New threaded probes were then attached with much greater success (figure 5 and 6), although the holes were not very straight and resulted in a wide space between the probe mount and the grounding point of the probe.

After some preliminary testing, the tuning plate was then added (figure 7 and 8).