Here's an idea. How about talking to the senior radio technician on the
military base? Just maybe he/she would have the answer.
================
Or borrow a handheld scanning receiver. It could well be that a nearby
transmitted signal ,not necessarily on or near 'your ' transmitted frequency
affect the RC receiver (which probably has limited immunity in respect of
strong harmonics/mixing sigs.)

Frank GM0CSZ / KN6WH