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Site Created by: |
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Chuck Rippel |
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Copyright: 1996, 1997, 1998, 1999, 2000, 2001, 2002 |
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See our copyright page for full information |
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The R390A/URR |
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Ultimate Performance, General Coverage AM & CW Receiver |
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R390A/URR Receiver Site Pages Accessible from Left Hand Navigation Bar |
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History |
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R390A history overview with Chuck Rippel, WA4HHG with Les Locklear 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. Stories are told that R390A's are still in use by the NSA where senior operators far prefer their quiet, yet stellar performance over mega-dollar receivers from Harris and Watkins-Johnson.
With all this, fate has not been kind to the R390A. My own involvement came around 1972. I was an active Shortwave Broadcast DX'er
at a time when direct frequency readout was a dream, the affordable commercial radio for a teenager was a Realistic DX-160, and the front ends of solid state receivers overloaded on every band. An R390A was advertised
in a local classified circular and I bought it for the princely sum of $400. Wanting full performance from that R390A, I put an electronics background to work and learned how the receiver worked. Years later, I still regard my R390A as an important and effective tool in my radio listening hobby. I also regularly restore R390A's for others. If you wish information on having me restore your R390A, clicking here takes you to the FAQ A personal experience which speaks volumes about the performance of a properly working R390A happened only a few years back. A group of some of the "heavy hitters" in
the SWBC DX community, myself included went on a DX'pedition to Cape Hatteras, NC. Known for its incredible radio conditions as early as 1902, Cape Hatteras was the scene of some of the early research done by radio
pioneer, R.A. Fessenden. Today, this remote location is a top choice for Medium and Shortwave Broadcast DX'ers. Quite an array of receivers had been brought along including a Drake R8 and R8A. A pair of
Watkins-Johnson HF-1000's, an R388, R390A and a JRC NRD-535. It was a particularly good morning with extraordinarily quiet conditions and a strong opening into the Pacific and Asia. Around 1130 UTC I checked 3304.8 for
the Radio Republic Indonesia outlet in Dili, once Portuguese Timor. Although it had not been reliably logged since the late 70's, it was there that morning weakly, just a het in the R8A. Everyone quickly tuned to the
frequency determined not to miss the opportunity to log such a rare station. However, even the $4,000 Watkins-Johnson receivers could not extract more that a few words of copy. Our R390A was equipped with a Sherwood
SE-3 synchronous detector and I quickly tuned to 3304.8. The R390A and Sherwood SE-3 extracted recordable audio from that signal when no other receiver we had could. That put the receiver in a whole new category not
only for me but the others in attendance. Of the R390A's I own, 3 are capable of sensitivity performances in the .07-.08uv for 10db S/N + N using the 4 kc filter and standard AM detection. I know of few receivers
available today at any price able to duplicate of that level of performance |
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Courtesy: Les Locklear - Gulfport, MS |
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