[Arran]

With regard to the Minerva, I see to recall that they originally had a circuit diagram posted somewhere inside the cabinet, kind of like a Sears-Silvertone radio, but who knows where it might have gone if it was even there to start with. From what I read these Minervas were originally designed, and manufactured to be, military morale radios, then after the war ended they switched over to making them for the civilian market as "Tropic Masters". Interestingly enough though there were also radios marketed under the "Minerva" name in Canada, but they were manufactured by Grimes-Phonola, then later Dominion Electrohome, they had absolutely no connection to the Minerva "Tropic Master" outfit, and were marketed by Eatons at one time.
Regards
Arran