Was planning a trip to North Coates.
Took Off from Sleap, without any reply from the A/G Tower, then called Shawbury for a Matz transit, they replied saying they were only getting carrier wave and no audio. I thought shall I continue without the radio, but then remembered North Coates requires a co-ordinated flight through the Donna Nook Danger Area.
So made a quick circuit and landed back at Sleap, where the engineer found an unsoldered wire on the Mic socket. (The other fault, a u/s AI he couldn't fix.)