Have mine stashed in the loft, had both the coastal fortifications, but when gaming mainly used the single gun emplacement. Last time I used it was with 20mm and Rapid Fire rules.
Somehow lost the aerial to the radio shack (many years ago - it wasn't glued in place), but found that the hole in the roof was just the same diameter as the plastic stem from a poppy, which looks almost like a loudspeaker....