R.F. noise from floresent lights is coused by the transformer that fires the light. The best way to cure the problem is replace them with an LED light or incadese lights. LED are now available in a lot of hardware stores or trailer supply houses. LED use less power and are not noisy to to AM radios.
The filter have to be RF filters on your radio. You may try it on the input power line to the radio but if the floresent light is broadcastin RF it may be getting into your AM antena.
Regards from Russell in sunny and warm Tucson Az.