Very interesting, Bill. I¹d never heard of the BP-10 before

It was one of the very first "personal portables," small enough to fit into
a coat pocket, and using all glass miniature tubes. Quite an engineering
feat for 1940.

Earlier portables -- and many later ones, too -- were the size and shape of
a small piece of luggage, and could more properly have been called
"luggables."

Phil Nelson