> "National Radio Institue".
It was cheap and may have been assembled by the student. It was not a wonderful 'scope even when/if it worked.
If the CRT is missing, just build a fish-tank into the carcass.
It was surely private-labeled by one of the big low-cost 'scope companies. Later NRI 'scopes were HeathKits with minimal features. Before Heath got into 'scopes NRI might have contracted with DuMont, who pioneered workbench 'scopes then got into money troubles. RCA often had a line of workbench 'scopes, but at various times RCA offered schooling and you just never can guess if the 'scope factory would cooperate with a competitor in the schoolin' racket. EICO also made a line of tube 'scopes which would be student-suitable and EICO could not afford to turn-away business.
So you wanna figure out what it "really" is, then work-out the cut-backs (3-position switch instead of 9-pos, etc) by inspection.
> There are eight tube sockets.
What type, octal mini-7 mini-9? Are there tube-types printed next to the sockets?
Maker-names on power transformer, inside the chassis?
Date-codes on transformer, filter-cap, CRT?
AC/DC switch at front input?
