I would test the antena booster to start. Then I would cross test the continuity of the coxail and 110 volt and 12 volt wires. maybe a pinch wire from a wire staple has rubbed through the insulation of the coxail and a power (110 v/ 12v) wire under the same staple, It could be the culprit, hadstaple
do somthing like that one time.
The other consideration is that the electrican who tested the pestal for you, might not know how to use a meter correctly and/or he might be the one who mis wired the pesttal in the 1st place. Did you talk to fellow campers, anyone else had simular issues?
