This is a work in progress! I would like to use a radio without vox functionality as an APRS node. To do this, I need to create a vox circuit. I decided the circuit by KH6TY was the best starting point -- see it here. I didn't want to try messing with autotransformers, so a friend of mine gave me some suggestions and I further modified it to obtain the following:

It's not quite working yet, so more testing is necessary.