[R-390] "Classified" R-390A Receivers

[Al Tirevold]

In my research, I have come across exactly one reference that is classified - 
"Restricted" - and that is The Final Engineering Report on Radio Receivers 
R-389( )/URR and R-390( )/URR from 1953-Sep-15.  I suspect that that 
classification is an internal Collins radio item, not an official government 
classification.

The document is at http://www.r-390a.net/faq-eng-r3.pdf

The radio was frequently used within a secure 'classified' environment.  The 
uses to which the radio was put and the frequencies that were used were often 
classified.

I have found no evidence that the radio was itself, ever 'classified'.  

Al Tirevold, WA0HQQ
www.r-390a.net
..