Through the wonder of Google Maps Street View I was able to discern remotely that 104 Halsey Street, Newark is now a clothing store specializing in Denim. I doubt the current proprietor knows that those walls housed a school for would-be radiomen for most of the last century.
I found a single advertisement in the Lowell Sun Newspaper that lists them back in 1922. That seems spurious. But in the 1940s The United States Radio & Television Institute occupied the space 96 through 106 Halsey Street. This is no coincidence, it's the same school or a related entity. It was WWII. The school probably ramped up to accommodate technical training for military cadets.
They also had classes for Women's Auxiliary Army Corps. After WWII they continued to teach radio repair classes. I scanned a 25 page pamphlet they were using around 1940. It's available here as a PDF.
They were still around in the 1950s, and were advertising in Radio & Television News Magazine. After that the trail drops off. The 1959 guide to Colleges and Specialized Schools continued to list them, but now the address is 257 Washington Street - a block away. Lovejoy's Career and Vocational School Guide lists them as late as 1967. College Blue book continues to list them at that address in 1972. Then poof.
If any reader can tell me more, please do.