The Best Technical Reference for the R390A/URR free PDF

Discussion in 'Tuners' started by transmaster, Aug 20, 2014.

  1. Punker X

    Punker X AK Subscriber Subscriber

    Messages:
    3,917
    Location:
    Panic in Detroit
    Another ET here that also worked on them.. We had one in the ET shop all the HF receivers were R-1051's by my time.
     

     

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  2. AdamAnt316

    AdamAnt316 Collector of heavy things Subscriber

    Messages:
    2,008
    Location:
    MA
    Hey, an R-390A thread I somehow missed back in the day. I lucked out on one, plus a Collins R-392, many years ago. Both had been stored in the back room of my high school's electronics shop for many years, after being left there by a long-since-departed instructor. Apparently, there had been a couple more R-390As in there at one time, but all but one (plus the R-392) had disappeared over the years, leaving behind the examples which didn't work.

    I first discovered these radios during my junior year in the shop. At the time, I had a Hallicrafters S-118 as my main shortwave rig; picked up signals OK, but was extremely drift-y, and pretty far from their best work. I had little idea what these radios were, except that they were very large, and I was intrigued by the mechanical-digital tuning system, which was unlike anything I'd seen on a radio before. I inquired about the sets, only to be told that they didn't work, and to not bother plugging them in. :(

    Three long years passed. Some time after I graduated, I heard that the school was being renovated, and that the electronics shop would be moved to a smaller room in a different part of the building. I started paying visits to my old shop, dropping subtle hints about the boatanchors here and there. Finally, during one visit, the second or third thing out of my old instructors' mouth was "Hey, Adam, you want these old radios?" Needless to say, they got loaded into the back seats of my Dodge Spirit in record time!:banana:Here are some pictures of the pair, taken shortly after their acquisition:
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    First up was the R-390A, since I didn't have a power supply capable of the 28V@3A used by the R-392. I hauled it onto my workbench, and started looking it over. I'd heard many things about the 3TF7 ballast tube being a common issue, so I pulled it from its socket for an inspection. It looked fine at first, but on a closer glance, I noticed a tiny gap in its filament. Could it be that easy? :idea: I bought a replacement on eBay, restuffed the can capacitors, replaced some known trouble caps in the IF deck, hooked it to my variac, and started cranking up the juice. To my amazement, it worked on the first try, rewarding me with AM/shortwave reception I'd never experienced from any other radio! :D It soon displaced the Halli S-118 as my main shortwave rig, where it remained for several years. Here is a picture of it at work:
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    I have owned numerous shortwave receivers in the years since. From similar military receivers like the R-392 (which required more fixes than the R-390A, but did get repaired) and R-1051B/URR (a fine receiver, but a pain in the ass to do anything with besides tune to a specific frequency), to more civilian-grade boatachors like the Hammarlund HQ-129X and National NC-183D, to more modern "canoe anchors" like the Panasonic RF-4900 and the Drake SSR-1. After all this time, I still have a soft spot for the R-390A. It's currently in the basement, waiting for me to modify an old Bud cabinet to fit it, and perhaps a little more preventative maintenance, but it shall soon reclaim its rightful place in my shortwave listening rig. :cool:
    -Adam
     

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