Mic hum

Question

Hello, I recently obtained a Superstar 140 radio without a mic. I connected a mic from a uniden pc76xl and every time I key up there is a loud humming noise coming from the mic. It does not come from the radios speaker but through the mic itself. Would it be that the wirin gis different on these radios. If so where can I get the diagram for the wiring. The mic is a from a Galaxy radio. Any help would be appreciated.

Thank You.

Nef...