I'm not familiar with the equipment you mention but you are likely better using the high-level input than the mic input, which is easily overloaded. If the radio sidetone (your own voice) is clear in your headset, your recorder might be suffering a bit of RF feedback when the transmitter is keyed. If a change of input, or using the GoPro as suggested above doesn't work, there are various location, filtering and grounding fixes which can help with RF pickup. Out of interest, are you flying a metal or composite aircraft?