Bulkhead connectors for antenna feedthrough
I just happened to be looking in the April 1985 issue of Ham Radio Magazine and came across a "hint" in the Ham Notebook Column. This "hint" was how to use 1/2 inch EMT ("conduit") connectors that can be found at hardware stores and home improvement centers with regular PL-259 and PL-258 ("barrel" or "double female") connectors to get a water tight connection through a metal plate such as might be used in a wall, under a window, and so forth. Also, the metal plate provides an entry point ground for the coaxial cable shield which is recommended for lightning protection.
It seems that the outside diameter of 1/2 inch EMT is virtually the same as the outside diameter of a PL-259 UHF male connector. What is used is a 1/2 inch EMT junction box compression-type connector which will mount directly to the metal plate with a provided nut. The PL-259 is then inserted through the connector until the outside ring comes in contact with the compression part of the junction box connector. Then the compression nut is screwed onto that part of the junction box connector. Next a PL-258 is screwed onto the PL-259 and then the inside "jumper" cable can go to wherever desired.
I have attached the sketch of this which was included in the magazine. Since the entire article is copyrighted I did not include the entire scan of the short article.