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Thread: JRC repair tips and tricks

  1. #1
    Administrator N8YX's Avatar
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    JRC repair tips and tricks

    We don't have a forum area for discussing repairs to late(r) model gear so I'll park this thread here until such time as we create one.

    JRC gear has to be used to be appreciated. I was peripherally aware of the stuff until around this time a couple of years ago, at which time I got hold of a DOA NRD-515. None of the equipment can be considered boat-anchor, hybrid, etc. as it's all solid-state. Even the earliest amateur and commercial (marine) gear used some pretty sophisticated concepts and techniques in the equipment lines, particularly at the RF end of things. The results are some of the quietest receivers and the cleanest transmitters I've ever played with. If you can sound better than an FT-102, you're doing something right - and I can A/B the JRC and Yaesu rigs at will.

    My current inventory of the gear includes NRD/NSD-515s, the NDH-51x memory units, several NRD-525s, a couple of NRD-535s, a JST-135 and a Raytheon RAY-152. The latter is actually a re-badged JRC JSB-176, which is a stripped-down JST-135 with a marine-style display/front panel unit and a mission-specific firmware set.

    The -525, 535, -135, -152/ -176 all share some common DNA in their various circuits - especially where the plug-in cards are concerned. Some are re-usable across models; others aren't. As I walk through various repair procedures and configuration options I'll try to present a road map of what's what.

    Note that I won't be covering the NRD-545 or the JST-145/245 series of equipment. Those are the last amateur/hobby models which JRC produced before they pulled out of the amateur market altogether, and use different architectures than their predecessors.
    "Everyone wants to be an AM Gangsta until it's time to start doing AM Gangsta shit."

  2. #2
    Administrator N8YX's Avatar
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    Tip 1 - ALWAYS check the rig prior to power-up

    I got a decent deal on a complete RAY-152 setup which had a couple noted problems. Distortion on SSB; dim back light. After the rig was unpacked and visually inspected I put it in the lineup with an antenna connected and proceeded to test it out. The radio is spec'd at 150w PEP and whomever was using it prior had the power control (internal adjustment) set to almost DOUBLE this value. Yeah, that'll distort. Remove covers, start servicing procedure. Eventually I discovered the balanced modulator was allowing some BFO leakage, resulting in ~200mW carrier in SSB TX. Definitely noticeable to my area 10M buddies. Studying the schematics, I saw a SN16913 DBM used as a balanced modulator, similar to what Yaesu did in the FT-817. Unlike Yaesu, there is no Carrier Null pot included in said JRC circuit. I decided to inspect the board to see if it had simply been omitted, but my JST-135 doesn't have one either - and it's very clean (in proper tune).

    Hmmph.

    Removing the board suddenly revealed the nemesis of JRC - their choice of mechanical SSB/CW filters. These were packed with a foam substance which turns to a gooey mess and greatly affects the passband of the filters.

    https://people.zeelandnet.nl/wgeeraert/koku/koku.htm

    I've repaired at least ten of these things since acquiring my first JRC receiver so in I went. Better...but still some BFO leakage present. The radio went on my test bench, where extender cards were used to elevate the Filter Unit (CFH-38A) out of the card cage for inspection. Application of power resulted in Factory Smoke(TM) being emitted from somewhere behind the front panel.



    See the "Phones" jack in the pic below (not my rig)? Somehow in a previous life it had been snapped off internally - and as luck would have it, the jack's Ground lug hit just the right place (the +9V rail for the front panel) to cause a filter choke to burn up and render the radio inoperative. Mind you, this rig passed the Rattle Test before I put it on the bench the first time.

    When I disassembled the front of the unit to inspect things I found a couple more potential time bombs...but we'll address those as soon as the parts to fix this mess arrive. Also need replacement EL panels - and looks like I'll be making (trimming) my own.

    wir.skyrock.net.jpeg
    "Everyone wants to be an AM Gangsta until it's time to start doing AM Gangsta shit."

  3. #3
    Pope Carlo l K6BSO's Avatar
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    Look on the bridge of any large ship and you’ll likely see two brands of radio: Icom and JRC. Both are big in the maritime sector.
    My Dearest Karma
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  4. #4
    Administrator N8YX's Avatar
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    Quote Originally Posted by K6BSO View Post
    Look on the bridge of any large ship and you’ll likely see two brands of radio: Icom and JRC. Both are big in the maritime sector.
    And this is why JRC stuff rarely appears on the used market - though DSC and GMDSS requires might change that. People love the radios from what I've gathered.
    "Everyone wants to be an AM Gangsta until it's time to start doing AM Gangsta shit."

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