i have no trouble wiht my harbor freight generator, to run radio, charge deep cycle batteries, i would suggest you try them out, inexpensive to say the least, the trick is to buy the long term warranty, if ti does not work take it back and get another. they honor the warranty no question asked. some guys just automatically trad in their equipment before the expiration date every year and get new stuff. mine works ok , charges batteries and runs about 6 hours on a gallon of gas. and running the charger or charger off no difference in interference.
alex
w3xh