[TenTec] 450 OHM LADDER LINE FEED THROUGH FOR LOW POWER OPERATION.

[ac5e at comcast.net]

Well, the last time I was around the Matagordo country the mosquitoes were about big enough to fly away with small children. And according to rumor did fly away with a couple of wash pots. So I do understand you want to keep them out of your house. Especially since West Nile Virus has become common. 

But really, HV insulators are overkill unless you are running some serously high power. We used to drill two holes an appropriate distance apart in a piece of plexiglass (lucite) and replace a window pane, solder a lug to each wire of the outside run of ladder line, run #8 screws through the lugs and through the plexiglass. A nut on the inside secured that part. Two more lugs on the inside run of ladder line and a couple of more nuts finished the feedthrough. 

Plastic would be better since it does not absorb water - and in window pane sizes it should be cheaper - but if you must use plywood a few coats of Varathane or a similar varnish should keep the wood dry. 

73  Pete Allen  AC5E

Never squat with your spurs on!