You are not going to believe this. At Field Day last year at our club, a electrical buzzing was killing 80M phone. I took restored 1965 Sears 100 mW CB walkie talkie with the antenna retracted, and found 2 sources of noise within the Clubhouse. Both switching power supplies wall wart style. And the only reason I brought them was to show the build quality and test their function after being restored. IOW, they were supposed to be eye candy. But they led us tight to the noise. Any 100 mW superhet walkie talkie should work.