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Thread: MCS2000 Loud RX PL in the speaker

  1. #1
    DoninIA No Longer Registered

    Default MCS2000 Loud RX PL in the speaker

    Hello all, new to the group.

    I just bought a MCS2000 VHF and have it all programmed up.
    My problem is that when I have Monitor ON, and I am using a repeater that sends PL, I can hear the PL tone in the speaker.
    The tone is extremely amplified. It's like the radio is not filtering it.
    Now when I turn Monitor OFF, the speaker returns to normal, PL seems to be filtered properly.
    I know years ago this was an issue with the HT1250 when it first came out and I believe a firmware upgrade fixed it.

    I currently have firmware version 5.80, so I'm hoping this is not going to require a firmware upgrade.
    This is just for amateur radio use.

    I've done some searching and have not found anyone with a similar problem.

    Thanks,
    Don


  2. #2
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    It's hard to diagnose this problem remotely, without actually trying several things. But here's a few possibilities:

    - Current/final firmware is R07.73. Unknown if this is the cause (no enhancement list available) but might be worth a shot.

    - Could be that the repeater's tone is overdeviated. Standard deviation (on a 5 KHz channel) should be about 700-750 Hz.

    - Is it possible the repeater itself is not filtering the PL from the RX input? If this is true, then there could be phase distortion you're RX'ing from the repeater output. This happens when two PL tones -- slightly out-of-phase from each other, are present on the repeater output (input + output mixed). Some radios have a really hard time with this. It can make an annoying out-of-phase rolling type of sound, but usually isn't too bad. Repeater requires a high-pass filter on the input audio. A Quantar does this job nicely

    - Emphasis/Deemphasis settings in your codeplug. If you have them disabled, this could contribute to the PL humming. When enabled, they filter the audio and amplify/process certain audio ranges.

    - Quality of speaker. Some have more bass response than others. Personally I like a bassier speaker at home, but higher-response sounds better in the car.

    Again, very hard to diagnose remotely. I do offer firmware upgrades for the MCS2000, but by no means am I trying to suggest it will fix your problem. I don't know.

  3. #3
    DoninIA No Longer Registered

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    Thanks for the reply Mars.

    I have thought about the firmware upgrade, going to contact you off list if I go this route.
    I don't have a lot of $$$ into this radio so that is an option.

    The repeaters tone is running about .8 Khz.
    This is on my repeater.
    I have tried others and still have the problem, BUT all those repeaters were set up by me (MSF5000's).

    As far as the PL from the receiving radio being passed to the TX audio, I guess I couldn't rule that out.
    I should be able to see a PL oscillation on my scope when I look at the TX audio.
    I will test that next.
    Again, the repeaters were setup by me and if I got one wrong, I'm sure they all are.

    I've tried turning RX Emphasis on/off, no change.

    As far as a speaker, OEM Motorola.

    Back to firmware, the techs that I have talked to thought that if this was an issue, it certainly would have been resolved by 5.80.

    Again, thanks for the reply.
    I think I'll try lowering the PL deviation and see what happens.

    Don

  4. #4
    DoninIA No Longer Registered

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    Update,

    Mars, I have lowered my PL deviation to just under 700 hz and I can barely hear the PL
    in my speaker, Monitor ON or OFF, interesting.

    Looks like I will be going mobile with the service monitor arghhh.

    Thanks for your help !

    Don...KI0EO...

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    PL deviation should be under 400 hz unless your using a high tone like 200hz plus then 500 hz is more than enough.

  6. #6
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    Not for a wide band system. If you go less than 500 Hz you are going to have problems. 750 Hz is spec, most people run about 600-800 or so.

  7. #7
    DoninIA No Longer Registered

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    Agreed, I never go below 600 Hz. Big M spec is 750 Hz.
    I set my MSF5000 to have a maximum deviation level at around 800-850 Hz.
    This was a little high, but it gave me the best audio linearity with my repeater controller.

    Although my radio is much happier now, it's still odd that when I switched between Monitor ON/OFF I could mute the PL.

    Don

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    Quote Originally Posted by Notarola View Post
    PL deviation should be under 400 hz unless your using a high tone like 200hz plus then 500 hz is more than enough.
    PL deviation is supposed to be 15% of total system deviation;
    So for a 5kHz wideband system that would be 750Hz
    for a 2.5kHz system, a.k.a. narrowband that would be 350 to 375Hz