For what it's worth, this is my approach to the double-hung window panel.
I built a long, narrow box out of 1X8s, sized to fit the window sill. A
sheet of aluminum sits in a groove inside the box to form the actual panel.
It is drilled for coax bulkhead connectors and Jones plugs for other
conductors. Standard electrician's copper hardware, plus a stainless steel
screw, nut and washer, are used to connect the panel to my ground lead.
The box is screwed to the windowsill with two wood screws. I had thought
it might be necessary to put insulation on the back of the aluminum panel,
but so far that has not seemed necessary.
On the outside, there is a hinged vertical panel that hides the backs of
all of the connectors (my wife likes this much better than without). The
cables come out through the bottom, where the 1x8 is cut out to provide room.
In use, the window sits down on the top of the box with a strip of extra
weatherstripping providing a good seal. More weatherstripping closes off
the opening at the top of the raised lower window. I had storm and screen
panels made that fit tightly from the top of the box in the original window
recess. That did not cost much at all (under $60 for both).
73, Pete N4ZR
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