On weak AM channels my after-market radio is "staticky" but these stations aren't weak in my wife's car. Other AM stations are OK. The static goes away when the engine is not running and does not seem to depend on revs. I have changed plugs, wires, cap and rotors. What else can I do ?

Thanks for any help/suggestions

 

remove antenna plug from back of radio, clean and plug back in.

 

The antenna plug and mast are for FM stations...AM stations rely on the sterio itself or sometimes the whole grounding system for the car as an antena. If you're getting static while the car is on the problem could be a bad radio supression relay. If you have an aftermarket system (i.e. an amp and sub woofers or capacitor) then it could be that you ran the power line too close to the exciter line off the battery or charging line from the alternator. Though i suppose if it were too close to the charging line you'd notice the difference when you revved the engine. You could try re-grounding your sterio too.

 

Thanks. I'll try those suggestions.
where is the radio suppression relay?

 

Depends on which car you have i supposed...Maybe behind the glove box with the other relays? I really have no idea where it's at but I know Tech does.