I don't see any reason why the file shouldn't work. I suspect that you may be having simulcast issues. If you have the squelch fully clockwise, you will be lucky to hear anything. Only extremely strong signals will override it. The normal procedure is to set the squelch fully counterclockwise and turn it up until the noise just stops. The owner's manual suggests a normal range is 10 to 12 o'clock. Try setting it fully counterclockwise and see what happens. Without conventional frequencies, you should not hear any noise. If you have a strong signal, with the squelch fully counterclockwise, try turning on the attenuator. That will sometimes reduce the number of towers you receive and improve the control channel decoding. Also, try pointing the antenna different directions and move the scanner around the room. Are you in Marion Co? If not, how far from it? If you are using an outside antenna, try the stock antenna. If you have a weak signal, you may require an outside antenna or a high gain scanner antenna such as the Remtronix REM-800B. That one is made specifically for the 700 and 800 MHz frequencies and works far better than the stock antenna.