I used C150 horns for my homebuilt and with long drill bits bored holes
through for both the PTT and AutoPilot.
See http://www.abri.com/sq2000/finish08.jpg and
http://www.abri.com/sq2000/instrument09.jpg

Henning DE wrote:
Hello Cessna owners !

I want to add PTT-Switches to the controls of a 1977 172N.
Since the control horns are not hollow i don`t know how.

Any suggestions ?

Henning Dammann-Emden
Bremen/Germany