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Thread: Motorola Alert Monitor.

  1. #1
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    Default Motorola Alert Monitor.

    Looking for any info on these units. Tried a quick google search and nothing.

    I have two of these units. Mainly I'm looking for a model number break down and frequency ranges.

    Here are the model numbers of the two I have.

    M01CNB3100A- I know this one is low band currently hasImageUploadedByTapatalk1366582340.825068.jpg a rock in it for 39.04

    M03CNB1100A-this one is VHF hi with a rock of 151.340


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    These are great units, what seems to fail is the power supply filters seem to go bad and they induce hum. Changing out the caps seems to fix this issue. Some had decoders in them, either PL or two-tone or both. There were even some two frequency ones. They have a great receiver, albeit wide band now, but I still use mine, and mine are all PL. You will need vibrasponders for PL decode.

    Surprisingly easy to tune, and ICM still makes crystals for them, just give them the model number. What is difficult to find are the power cords. These run on 12vdc or 110v.

    If yours has an internal battery, might want to check on that puppy and make sure it isn't leaky.... Oh, and did I mention the AWESOME audio??

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    Quote Originally Posted by com501 View Post
    These are great units, what seems to fail is the power supply filters seem to go bad and they induce hum. Changing out the caps seems to fix this issue. Some had decoders in them, either PL or two-tone or both. There were even some two frequency ones. They have a great receiver, albeit wide band now, but I still use mine, and mine are all PL. You will need vibrasponders for PL decode.

    Surprisingly easy to tune, and ICM still makes crystals for them, just give them the model number. What is difficult to find are the power cords. These run on 12vdc or 110v.

    If yours has an internal battery, might want to check on that puppy and make sure it isn't leaky.... Oh, and did I mention the AWESOME audio??
    The two units I have don't have any internal batteries and they both run off 110v.

    The low band one I have has a PL board in it. The high band one is just a receiver with no signaling boards at all.

    From what I hear there is a guy in Ohio that will narrow band these.

    The one on 39.04 I would like to re crystal for 46.36 if possible.

    I know when it comes to some of the Motorola stuff some of them have different freq ranges.

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    And they seem to have no issues with any power supply hum. I do have a regency ACT R1 that has a humming issue.

  5. #5
    wd8qwr No Longer Registered

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    No need to NB the low band radio. 46.36 isn't a NB freq.
    HB versions aren't that hard to do, if you can find the IF crystals. I think Comm-Spec carries them.

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    Quote Originally Posted by wd8qwr View Post
    No need to NB the low band radio. 46.36 isn't a NB freq.
    HB versions aren't that hard to do, if you can find the IF crystals. I think Comm-Spec carries them.
    I'm fully aware about the LB one. I recently got my hands on a Federal Voice Alerting Receiver aka Plectron R9000, That is on the LB freq I wanted.

    The HB one I wanted to NB but to be honest it works just fine the way it is, just have to raise the volume a little more.

  7. #7
    wd8qwr No Longer Registered

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    You can improve the S/N by changing the IF crystals and retuning, but that is about it. It has been 30 years or so since I modified one. We are on a 6.0Kc channel, so I know what you mean by turn it up. I have never done the Plectron.