The venerable R-390 series HF receivers are still in use today by ham radio operators and collectors. It is one of the best receivers, of it's type, ever made.
The Collins designed, R390A/URR general coverage HF radio receiver is considered to be the finest HF radio
receiver ever built. Tuning .5 to 31,999 mhz and employing 21 vacuum tubes and weighing in at 85 lbs, this electro-mechanical wonder was designed in the
early 50's and released for military use on February 24, 1954. Thanks to features such as a 6DC6 first RF amplifier, a suite of 4- Military Grade Collins mechanical
filters teamed up with full tracking RF and IF sections, the R390A is capable of copying AM and CW signals down to its -143db noise floor, close to the galactic limit. All this while maintaining the
capability to operate in high overload, strong signal environments.
Originally built by Collins Radio Company in Cedar Rapids, IA, the R390A was
designed by 2 teams. The mechanical team was lead by Fred Johnson while the electronics team was overseen by Collins' Ernie Pappenfus, K6EZ. Besides Collins Radio, 12 other sub-contractors built
R390A's until the last one rolled off the assembly line in 1984. Banks of these fine radios served the country in all branches of the military. Additionally, they
found service with the CIA and NSA to monitor communications from behind the Iron Curtain. During the Cold War years, the R390A was so valued it was classified TOP SECRET, a security
measure which remained in force until the mid-1960's. From: