[OZAPRS] Cavity info

[Tony King]

Hi All,
I am currently in the process of finalising an APRS repeater for 
coexistence with the Yarra Valley Amateur radio groups 2m repeater and 
am at the point where I need to machine up a cavity or two.

Can anyone point me to a suitable amateur design for a 2m unit as ex 
commercial ones are a bit thin on the ground here at the moment.

Actually any design formulas would also be appreciated then I could 
design my own.
                                                                                        regards Tony VK3API