Steve D. is right about the Tm-21. The transformers and chokes are all hermetically sealed and potted. With the exception of the flyback. All power supplys are regulated and if I remember even the filaments receive DC. It used either a 21cyp22 or a 21fjp22 CRT.
I had a mint example of this set, but sold it to Dan Gustafson 15 or so years ago. Darned Heavy ! Each side of the case has 2 large self retracting road case handles on each side. The chassis is composed of sub assemblies mounted on a frame all cabled together via Jones plugs. An easier set to service couldn't be designed.
According to my copy of "Closed Circuit Television Systems- Color and Monochrome Fundamentals-Planning -Applications" published by RCA in 1958, and prepaired the Government Service Department , RCA Service Company, RCA sold stock studio equipment without special componentry. All devices shown are stock RCA with
the exception of Huston-Fearless camera dollies and mounts.
But if the electronics are built as the TM 21 is built, I don't see how it could have been improved upon at that time.
A paragraph at ther bottom of the title page states " This research was supported in whole or in part by the United States Air Force under contracts AF 30(635)-7557 and
AF 36(600)-3468,Call RM 57-3 , monitored by the Systems Engineering Division, Directorate of Maintainance Engineering , Rome Air Force Depot, Griffiss Air Force Base
New York.
It appears that a tricolor system was installed at Walter Reed Army Hospital for instructional and training purposes.
There are also a couple of photos of monochrome cameras being used to provide support of remote defusing of bombs.
I hope this is usefull !
