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Thread: MCS2000 - excessive PL bleed on RX?

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    Default MCS2000 - excessive PL bleed on RX?

    Hi everyone. I have two 900 MHz MCS2000s. Aside from the characteristic "lazy squelch" just before they mute, they have another annoying problem. On RX, the receiver seems to pass PL tones rather loudly -- enough so I can always tell when my MCS2000 is unmuted without looking at my radios. I do not have this problem with my 900 Maxtrac. Under the same circumstances (frequency, antenna, etc.), the Maxtrac produces nice pure audio.

    Has anyone else noticed this? Might this be a problem that a firmware update could fix or does the MCS2000 just allow RX PL to bleed through more than other radios?

    Thanks,

    Norman


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    I have no experience with the 900MHz units, but haven't noticed this as an issue with other bands. Is it any PL, or perhaps just the higher 192Hz+ range? Any difference with 'hear clear' on or off?

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    Quote Originally Posted by Ice-T View Post
    I have no experience with the 900MHz units, but haven't noticed this as an issue with other bands. Is it any PL, or perhaps just the higher 192Hz+ range? Any difference with 'hear clear' on or off?
    Hi Ice,

    I've noticed this problem with any PL, unlike my Maxtrac which produces nice clean audio using the same PLs. Most of the guys in my area don't like Hearclear, so I have it turned off.

    Norman

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    I have always found the hear clear to sound 'punchy" . I modified a ton of 900 maxtracs to disable the hearclear on rx. The pl bleed through is bad on some of the radios. I remember "discussing" it with Moto in the past. Although they denied any problem I remember tracing the issue to a wrong value cap in the high pass filter circuit (.01 instead of a .1?? ). This only happened in a certain production run so that explains why some radios have it and some dont.

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    Something makes me think there's an ANCIENT SRN about this PL issue. I can search for it later. What firmware version is installed in your radio, Norman?

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    Is the problem just on RX, or does it do it on TX as well?

    I have seen several radios that were programmed for narrowband hear a wideband signal, and the PL deviation from the wideband radio is about double what the deviation would be for a narrowband radio. This may be what you're experiencing. It's a shot in the dark, but it might be a lead for you.

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    Thanks for your note. No problem with TX -- just on RX. Not many 900 systems out here, but the few that are are mostly narrowband. I hear what sounds like unfiltered PL on all of my channels on the MCS.

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    Please post your firmware version, Norman. Current firmware is R07.73 (final release)

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    Hi Mars. I'm at 05.58. I knew I wasn't current, but sounds like I'm pretty out-of-date.

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    Yes. I'm not sure how old that is, but I can tell you some of the older ambulance radios I've upgraded had 5.22, and hadn't been touched since early-mid 2000. Quite possible you have decade-old firmware in there.

    If you'd like a bump, I can do it. Anyone else who has MCS flash hardware is also welcome step forward. By no means am I trying to pimp the post.. LOL

    I'll also check my archives for you tonight and see if there's anything mentioned by Moto in a dated SRN about your PL issues.

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    Cool -- thanks Mars. Please let me know if there are any significant changes since 05.58 that might improve my situation (conventional HAM use).

    --Norman

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    Quote Originally Posted by Norman View Post
    Cool -- thanks Mars. Please let me know if there are any significant changes since 05.58 that might improve my situation (conventional HAM use).

    --Norman
    I wish there was a list of fixes/enhancements for MTS/MCS firmware. Unfortunately Moto never did release one.

    I just finished uploading my motherload of archived Service Release Notices (SRNs) for older products. You may wish to peruse through them to become familiar with the types of things newer firmware addresses.

    https://www.p25.ca/SRN/SRN_Mobile/ and https://www.p25.ca/SRN/SRN_Mobile_Data/

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    I've got this same PL issue with an M3 MCS 2000 UHF-H. It's running the "latest" firmware.

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    Im pretty sure its a hardware problem. Try a tone of 100hz and then 136.5 and see if the 100 is ok and the 136 bleeds through.

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    Yes -- the "bleed through" happens on all my channels which have different PLs.

    Thanks for all your comments. I'm glad to know I'm not the only one experiencing this. The MCS2K is nice to have but is harsh on the ears, especially on busy channels. No longer my favorite radio. Long live Spectras and Maxtracs!

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    scope pin 1 of U203 and see how much Pl is there. once again try a low medium and high pl tone to see if there is any rolloff. It is sounding like the AFIC U200 is not functioning correctly. This might be fixable by forcing one of the control lines low to bypass hearclear.
    It is a 900 meg radio your having issues with correct? also try a DPL and see if you hear the "wubble wubble" (great technical term LOL).

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    Thanks for the tip Notarola. Not sure when I'll be able to get around to scoping U203, but I'll keep that in mind. Yes -- it is a 900 MHz MCS2K. I do love the term "wubble wubble".

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    On the software end try disabling hear clear. When I was modding maxtracs we enabled hearclear on tx and disabled it on rx. A simple mod forcing enabling the hearclear board with a transistor on PTT. I remember loking at some info on the hear clear and if i remember correct the board likes unfiltered rx audio in hearclear mode.