Tom-H said:
Well, 463 mhz times 2 is 926 mhz, which would be in the range of the 900 mhz phones, but I was told that harmonics don't work this way, so who knows what's going on.
It's the frequency + or minus twice the IF frequency which, these days, is so high that you'd have to very close to a powerful transmitter to receive an image. The Pro-95, for example, has a 380.8 MHz first IF, so images would have to be 761.6 MHz from the actual frequency - which the front end filters would kill. (You'd probably get more 1224 MHz signal leaking directly into the demodulator through the plastic case - at 455 KHz - than would come through the 450 MHz filters.)
Three times the frequency is also possible if the transmitter is putting out harmonics, or there's something near the transmitting antenna producing harmonics (like a rusty joint between two pieces of metal). Or it could be intermod, if it's not continuous, which it probably was (continuous, not intermod) in this case.