hmmm thats really weird but i wouldnt think that one ballast could iinterupt a neighbors radio frequency.maybe several hunderd. i mean if thats the case than every time some one turned on a microwave it would have the same affect.personally i would say fuck him,do your thing.or switch to a magnetic basllast.do a test.if your cell phone has no interference next to your grow room i promise u it wont b affecting his radio.i worked in rf site building/cell communication for years and this scenario would b one for the books.