radio and depth finder

I notice that when I key up my radio my sonar will show bold solid vertical lines on it. When I let go of the mic it stops. What is causing this?

 

Your radio wiring and antenna lead might be to close to the transducer lead.

 

It is caused by radio interference. There may be a bad shield somewhere. For example, a damaged coax wire or a faulty ground.

 

Your radio shouts with 25 Watts RF power while your depth finder listens to milliwatts reflected from the seabed. Both signals are conveyed by coaxial cables that shield the signals from the outside world.
They can only do that when the coax shield is properly grounded. My guess is that the antenna cable makes no contact with the plug or the radio itself has a poor ground lead.