Flying in Southern California is nearly impossible without a Mode C transponder. I installed mine tonight after giving quite a lot of thoght to how best to support it. I made a simple 3-side box with 15mm flanges to go underneath the transponder and around it and the map box. This provides the needed lateral support for these fairly heavy items. All that remains is to put the transponder mounting tray in the final position and secure it.
Map box and transponder reinforced and placed
View of support system for transponder and map box
