Hey Randy ,
Wild guess -maybe a (skywave ?)1140 harmonic ? Perhaps try a second receiver on 1140 to see if the audio lines up with 2280.
FWIW, our local 850 puts out a rather nasty spur on 1700 audible for 4 or 5 miles from the transmitter site on local ground wave. Fortunately it dies out around 95% + when approaching my home , so no issue here.
K