Radio Shack sells a polystyrene or clear plastic type of feed-through bushing
just for this type of application. It is about a foot long and will allow RG-8
to run inside of it. It has a gasket on each end. Once you have installed it,
you can use the caulking to fill in any gaps, insuring an air-tight
installation.
Ken Maltz
Jericho, NY
NRD-535D, NRD-220 Collins R-388, Racal RA6790/GM,
ICOM R71A, ICOM R-7100(x2), AOR AR-8000
Panasonic RF-2200, Sony ICF-7600GR,
Hoka Code3 Gold-Pro, 60' long wire, MLB balun