On January 11, 2012 the National Security Agency (NSA) released a pre-1995 article entitled “Receiver Dynamics” from its classified internal magazine, Cryptologic Quarterly. It contains an excellent, well-written explanation of the specifications of shortwave receivers used by some of NSA’s K4 divisions.
Download the article here (PDF).
Thanks to Ed in the SWLfest list for the tip!
The Watkins Johnson shortwave recover was the best. J. D.