[dconant]

I'm not sure about the wave forms but if the noise you refer to is static then that might be noise from switching power supplies in your house or LED lights. I use a ground rod driven in the ground and connect that with a wire to the ground clip of the radio and that usually cleans up the static. Don't use house ground that will likely make things worse. My 89s use 8uF caps. It could be one of the coils is arching.

For a speaker plug you could use molex connectors. I don't bother with that. When I am satisfied with the radio I just put it back in the cabinet and call it done. Work out the problems while it is out of the cabinet.