Unless you know anything about repairing radios you should take it to a CB shop and ask them to check out the receive filter and if its bad change it . If you are using a cigarette lighter plug it will pick up static and other round noises also.Change the plug and hard wire it,see if the noise goes away. ground your antenna better.Does your radio have delta tune? if so make sure its in the 12 o'clock position.Try everything you can from the outside of the radio .If it is still there then take it to a tech.