G5RV 1/2 size

[G3TXQ]

Maurice,

Then I suggest you put the arrestor on the shack side of the balun so as not to upset the balance which we are trying to preserve. Then, for "belt and braces", consider a simple balanced-to-earth spark gap at the bottom of the ladderline like the one in the first photograph here:

http://kv5r.com/articles/ham/ladder.asp

73,
Steve G3TXQ