[Arran]

Actually you may be wrong there, there may be some appeal with the fact that this unit was supplied with a NRI radio course, and Triplett test equipment was usually of good quality. Test equipment from a correspondence course, especially early equipment, is not that common, not like Heath, Kinight, and EICO kit stuff. It's sort of like Philco branded test equipment, although Philco did not manufacture test equipment it is somewhat collectable because it says Philco on it.
Regards
Arran