A Cheap and Dirty Transponder Tool

A friend had a problem with his transponder. It didn't seat all the way in
the rack and would not connect with the coax(AT150).

I started thinking.....(I know) Does anyone out there know of a way to make
a simple transponder field unit that will transmit
the necessary pulses( 3, I think) at theone gig and change and then a
simple receiver to see if it responded(one shot and led).
Don't need squawk code or altitude..Any ideas....Jim!

This is probably an illegal device but at very low power, hmm?

John Prince Pitts N3DR