Complex sentence: In late 1941 after many rejects by McDonald (who personally did the testing on his yacht) Zenith engineers Gustaffson, Passow, Striker and Emde, came up with the model 7G605 "Clipper", that was met with approval by the McDonald after stringent testing.
Split into simpler sentences: In late 1941 after many rejects by McDonald (who personally did the testing on his yacht). Zenith Radio engineers Gustaffson, Passow, Striker and Emde, came up with the model 7G605 "Clipper", that was met with approval by the McDonald after stringent testing.