Tim, that's one helluva great idea and i may have to try it on some other meter !! But not having an ARR-5, 7 type rec, i am undermotivated about this one.

About 4+ decades ago a fellow told me he had an ARR-7 and i just HAD to have it, sight unseen. I offered him a Drake SSR-1, an SWL radio. Mistake ! The ARR-7 was missing the snout, plus it was not what i was hoping for. Live and learn.

I have a manual for an ARR-7 using mini tubes. Never seen such receiver myself. I think it was type ARR-7AX but not real sure about that right now. 

I like seeing the R. E. Goodheart ads in the old CQ mags showing their SWL ready ARR-7 receivers.

-Hue Miller