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Thread: xpr8300 PA failure

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    Default xpr8300 PA failure

    when the PA on the 8300 goes out, should there be something in the RDAC Event log? no red alarms on the status.. RDAC kinda useless? RSSI goes up when i key up analog on the freq. So i know antenna system is okay.


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    XPR8300's are famous for losing their output power. Thats one of the reasons for the 8400, but no they don't normally show any alarms when they fail.
    "Don't worry about what I am, cause I'm a state agent so what you need to do is make sure your doing the right thing **** boy" -J. Dewitte

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    Quote Originally Posted by Magnus View Post
    XPR8300's are famous for losing their output power. Thats one of the reasons for the 8400, but no they don't normally show any alarms when they fail.
    I know, thats why i did the full speed fan mod to keep it cool... guess it wasnt enough.
    When i get it down im gonna put a temp sensor on the Heatsink as well as a PTT sensor and connect it to a netdruino, so i can monitor whats happening, and cut of the TX if temp get to high.

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    In my personal experience, RDAC and XPR-8300 repeaters are a useless combination. Even if you open up an XPR-8300 repeater and start disconnecting TX/RX modules, RDAC will still show everything as green. Handy! I'm hoping this has changed in newer RDAC revisions, but likely not.

    No idea if things are better with the MTR-3000 or XPR-8400. Haven't bothered to waste any more time on RDAC once I discovered this.

    Cheers,
    SD.

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    The only thing RDAC is real handy for is checking to make sure all your repeaters are still networked and for looking at RSSI remotely.

  6. #6
    syntrx No Longer Registered

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    On the subject of XPR8300 PA failures... there are a few NIB 8300's around for decent prices.

    i'm going to put a VHF system on air, but probably only running 30W or so. With the full speed fan mod and light duty cycle, is this machine likely to survive OK or am I asking for trouble?

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    We got them to be reliable at about 20w for a fairly well used system.
    "Don't worry about what I am, cause I'm a state agent so what you need to do is make sure your doing the right thing **** boy" -J. Dewitte

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    I find the biggest thing is if your running ARS or not, we enabled it for a small GPS tracking experiment and even with just 4 or 5 radios on the repeater would be running at almost continuous duty.....whether or not the software was polling for GPS didnt make much difference... Also make sure you put a wattmeter on it and use tuner for checking the power settings, the CPS settings are rough indicators, last one I checked there was 8 watts difference between what CPS reported and what was coming out of it...

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    I have 4 of the original 8300 R01.00.xx hardware models, part of the original Dealer Demo Packs and while I have not lost any PA's, several other repeaters in our IPSC networks have. What we found was that the problem was the original mechanical method of transferring the heat away from the PA IC on the board to the underside of the chassis top cover was flawed. Motorola did not make use of the screw down method to transfer the heat. The double sticky transfer tape was the problem. Some shrunk over time and hot/cold cycles, others simple appeared basically not being sufficiently effective at transferring the heat.

    No problem with the cooling of the heat sink riveted to the top of the chassis cover and I never have run the fans at forced high and I run high power in both analog and digital with no failures to date (up to 4 years now on several). It is my understanding that R01.03.xx hardware versions actually changed the method or type of material between the cover and the PA. I don't open the covers simply to inspect as that breaks the mechanical bond needlessly. All IMHO, anecdotal and as always, your mileage may vary.
    -- Mike, NO7RF, Mazama WA

  10. #10
    madden No Longer Registered

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    Motorola is still selling the P8's and P10's (C5 Amplifier), those are a cheap way to get your 83/8400 up to 100W continuous duty and have it set way low at 5W. For half the cost, you get a more efficient Power RF increase than the MTR3000.

    I have installed over 200 XPR8000 series units and almost 60% of the 8300's have had PA failures... and continue to do so at least once 1-2 years. We did come up with a solution of added heatsink to the unit for protection..but just started reccomending the C5's without issue. We have about 50 or so C5's that are running a city-wide system that were originally installed back in 95 with some radius repeaters..we just reused them for the 8300's without a failure yet, in almost 20 years of operation. Nor have I ever seen a C5 go down that we have installed.

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    More info on the C5 amplifier please. Unfamiliar as to what you're referring to. Am interested in this.

    Thanks!

  12. #12
    syntrx No Longer Registered

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    Sounds like he's talking about rebadged Crescend amps.

    http://www.crescendtech.com/products...ut_power=20-50

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    Our local provider has used Crescend amps on 8300's before and they seem to be pleased with them.
    Cyrus

    Bubbles: I'd like to see that Red Blue Green c***sucker put one of those together, duct-tapin' it.