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Thread: Sudden onset poor sensitivity 5100ES UHF380 split

  1. #1
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    Default Sudden onset poor sensitivity 5100ES UHF380 split

    I bought, probably going to regret it, 10x 5100ES UHF380 portables last year, went through them, all great. Slight tuning, nothing major I can remember. I then sold some to ham friends so we could play on P25. I think they came out of a cache; clearly were not in service anywhere. Most still had the plastic display protector. So here I am thinkin Id gotten a good deal.
    I know of two now that were operating and rather suddenly lost a significant amount of sensitivity. The first one, he didnt know exactly when it happened, but it was on and at some point it just didnt hear as good. The second, it was like mid-conversation and he could hear the change in the receiver.
    I havent gotten those two back to look at, however, I had 4 left from that batch and I just tested them. Three are doing between -112dbm and -114dbm to open squelch. which is about 6-8db less than I would expect with wideband analog. There is one good one that opens right at -120.
    Has anyone seen something like this and poked around with one before, or am I gonna have to start at the bottom and try to trace it out
    Thanks.
    Oh, these are 6.16.x FW radios.


  2. #2
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    PIN diode tx/rx switch is known to go bad on these radios. Common fault. That's probably the first place I'd look.

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  4. #3
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    Ok, so I have to get the other two radios back in, but I discovered I didnt have 4 radios go bad while sitting. I didnt realize this, but it appears they have a birdie internal noise on 440.0000, which is the SNP pair my repeater is on. Some are affected more than others. If I reprogram them to 440.025 they all do about -122 in analog wide. What a relief. I just have to go get a new pair and move my repeater. Kinda a PITA but Ive already got these and at least I dont have to spend money getting new radios.