The one model I am aware of was the RCA 9-Int-1 which is very similar to the Graetz Melodia 519.
Read a discussion regarding the same question somewhere last year (possibly on the antique radio forums) that speculated on how it could have been that the Germans could at that time make a nicer radio for cheaper than RCA. I guess its like why so many companys outsource to China now.
Both the 9-int-1 and the Graetz Melodia 519 look similar inside. This is the inside of the Graetz-
