In article ,
Ron Hardin wrote:

Switching power supplies are notorious sources of birdies at every harmonic
of their (not very high) operating frequency, even when there's been some
effort to suppress them in design. I doubt a microwave oven has much
suppression.

Try plugging the radio into an outlet that's on a different circuit, you
may find one that's more isolated from the microwave. Or if possible,
run the radio from batteries, and see if that makes a difference.

--
Larry Weil
Lake Wobegone, NH