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Thread: Strange MTR2000 problem

  1. #1
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    Default Strange MTR2000 problem

    I have a VHF 100w Mtr2000 that shuts down immediately on ptt. All control board lights go out and the radio resets.
    The error log only shows station reset. Station diagnostics shows everything tested passed, unless the ptt box is checked, then itís resets as soon as testing begins. If I reduce the tx power from 100 to 60w every thing is ok. At around 75w it starts shutting down. Now for the strange part. I have a spare VHF 100w MTR2000 that I use for testing modules. I first though was either a PA, or power supply problem. I installed the power supply from the good working MTR, reset the power output to 100w and keyed up the station. Full power output, no reset, no error logs. Power supply problem right? I installed the suspect supply on the doner station, keyed it up full power, 100w no reset. Next I moved the PA from the problem station to the doner; instant shut down on tx. It seems that whenever the original PA and power supply are paired together, the problem occurs, when paired with different modules, they are ok. Looks like the complete station is headed to the depot. Anyone have an idea what is going on?


  2. #2
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    Sounds like the power supply is weak, and the PA draws a bit more power than it ought to.

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    Quote Originally Posted by aloha View Post
    Sounds like the power supply is weak, and the PA draws a bit more power than it ought to.
    +1

    The original RFPA has a problem, and continued use has weakened the power supply. I'd run it at 50W until it died. 3db down is not that big of a deal.
    Bow wow wow yippie yo yippie yay

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    Quote Originally Posted by JMINN699 View Post
    I have a VHF 100w Mtr2000 that shuts down immediately on ptt. All control board lights go out and the radio resets.
    The error log only shows station reset. Station diagnostics shows everything tested passed, unless the ptt box is checked, then itís resets as soon as testing begins. If I reduce the tx power from 100 to 60w every thing is ok. At around 75w it starts shutting down. Now for the strange part. I have a spare VHF 100w MTR2000 that I use for testing modules. I first though was either a PA, or power supply problem. I installed the power supply from the good working MTR, reset the power output to 100w and keyed up the station. Full power output, no reset, no error logs. Power supply problem right? I installed the suspect supply on the doner station, keyed it up full power, 100w no reset. Next I moved the PA from the problem station to the doner; instant shut down on tx. It seems that whenever the original PA and power supply are paired together, the problem occurs, when paired with different modules, they are ok. Looks like the complete station is headed to the depot. Anyone have an idea what is going on?
    Are you measuring power directly out of the PA or further down line like after isolator and duplexer?

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  5. #5
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    Out of the PA. I swapped out a third power supply and it shuts down like the original, so it looks like a PA problem. It will run fine when set down to 50 watts. I think that I will let it run at 50w and see how long it lasts. We have a replacement on order. Sure wish Motorola would make a real service manual available, but I guess that really won’t help since they won’t sell board level replacement parts.