Wondering if anyone else gets this problem. Loop ATU tunes to lowest SWR, transmits okay on FT8 for a couple of times and then suddenly a blip on the SWR knocks the Amp out. Retune and same thing will happen again. No wind. Rotator not moved. Loop fed by 30m of RG213 cable. Supporting pole earthed.
Grateful for any suggestions as to what might be causing this?