Modify A CM108 Sound Fob For AllStar How to modify a CM108 sound fob for use with Allstar A modified CM108 Sound Fob - Click to enlarge. Below are my legacy older designs.My latest design can be seen HERE Design 1. With regular components: LINKDesign 2. With surface mount resistors: LINKDesign 3. For use with commercial radios such as the Motorola GM340: LINK