[Elecraft] Recieved RF Signal Burst then very Quiet.

[CHRIS HANNAH]

Have a problem with my K3, Local amateur just 300yrds away from me,was transmitting and beaming direct at my antenna,My AFC was off, his audio and signal was so loud I think it has damaged part of the RF Stage,When I switch the K3 on the received audio is ok for about 2 mimutes then I get a rush of audio then it goes very quiet and distorted this carries on all through the QSO,
Any idea's please.
Many thanks de Chris G4LOP