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Thread: UHF MX300-S DES, DVP and DES-XL module interchangability.

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    Default UHF MX300-S DES, DVP and DES-XL module interchangability.

    I have been scouring the internet on the subject. Bottom line question. If I have a UHF MX300-S equipped with a DES or DVP module, can I plug in DES-XL module instead?

    I know VHF and UHF have different TX modulation considerations.



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    yes the modules are interchangable. Good luck on finding one though.

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    PM me what you are looking for on the MX radios, I still service / repair / program them from time to time. Don't think I have every seen a DES XL module but who knows what might be hiding in my boneyard.

    Andy

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    DES-XL for MX was very rare and only used by a few agencies like WHCA. The regular DES/DVP modules are 3 "units" side and the very rare DES-XL modules are 2 units wide, so they are significantly different from what I can remember. I have seen so few of them I honestly can;t remember if the connecting flex was the same, it might be, but the boards under the shield are different from what I vaguely remember.

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    I think they are the same flex. I will try and find a few old manuals and see if there is anything in them. Im curious now

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    Thanks Notarola. I am embarking on a conversion that involves hardware and knowledge that is long buried away. I would expect that if a DES-XL variant was developed, Motorola might have made it backward compatible somehow to appease the FED's who were not pleased with the 80% coverage of DES.

    Onto another question. 4 layer vs 6 layer MX boards. Was 6 layer to support the synthesizer, or was it to eliminate the Kapton flex for DVP/DES radios?

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    Quote Originally Posted by NC4AB View Post
    PM me what you are looking for on the MX radios, I still service / repair / program them from time to time. Don't think I have every seen a DES XL module but who knows what might be hiding in my boneyard.

    Andy
    What do you charge? I have an MX350 with MODAT that I cherish, and the TX audio has gone out on it. Everything is so damn brittle inside I'm afraid of making it worse.

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    Have you tried a remote speaker mike on the radio?

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    Quote Originally Posted by RFI-EMI-GUY View Post
    Onto another question. 4 layer vs 6 layer MX boards. Was 6 layer to support the synthesizer, or was it to eliminate the Kapton flex for DVP/DES radios?
    the 6 layer was to support the synth and to eliminate componants. It also cleaned up the board a bit. I believe that the encryption boards also used the same connection because moto didnt want to make a custom board/interface for the module. Back then few were interested in XL as they had already got the non XL DES.

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    Quote Originally Posted by Notarola View Post
    the 6 layer was to support the synth and to eliminate componants. It also cleaned up the board a bit. I believe that the encryption boards also used the same connection because moto didnt want to make a custom board/interface for the module. Back then few were interested in XL as they had already got the non XL DES.
    So am I correct in assuming:
    all MX300-S have a 6 layer board?
    all DVP/DES MX300-S have a Kapton interface overlay?
    all DVP/DES MX300-S share same Kapton interface overlay? Even VHF and UHF? I know VHF has different modulation scheme (direct to VCO vs offset element). Is the interconnect the same? Is the module different electrically? They do have different part numbers.

    I have a big gap in my manuals when it comes to early DVP/DES and Securenet stuff. I cannot find anything on the internet in the way of manuals.

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    Quote Originally Posted by RFI-EMI-GUY View Post
    Have you tried a remote speaker mike on the radio?
    I have not... Think I'll give that a whack this evening and let everyone know how I make out... Still need the radio fixed either way.

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    Quote Originally Posted by d119 View Post
    I have not... Think I'll give that a whack this evening and let everyone know how I make out... Still need the radio fixed either way.
    There are literally only a few parts to go bad. The mike cartridge, a blocking capacitor, the IDC module that plugs in, the IDC pot, the offset element. Since you have a MODAT board, there is probably a jumper removed (JU4?) and the MODAT switching the mike audio off during the duration of the MODAT. Then you have the control flex and the option flex.

    If the MODAT tones work, the Offset element is OK. If the remote mike works, the internal mike cartridge is bad.

    Personally, I would just open it up and reseat the appropriate modules and give the IDC pot a twist back and forth.

    Also, Motorola liked to use some black paper tape to insulate stuff in radios, even though fancy Kapton wiring was being used. I would check to see if you have any shorts between PC pins and the Kapton option flex.

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    The MODAT tones do work. Didn't get a chance to work on it last night, I'll try tonight and report back.

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    I found an old select IV SELCALL supplement for the MX3000, and in manual that the signalling tones and DC bias go into a separate pin of the IDC module, thus turning off the mike circuit with the 4.6V bias.

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    I have the MODAT supplement for the MX, fairly certain I have the R1801 stuff to program the PROMs as well. Haven't checked out the radio with a speaker mic yet. Will try to do when I can remember. I do want to get it fixed though.

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    Im still looking for the info on the encryption for the MX. I have it burried somewhere but its a matter of finding it.

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    Quote Originally Posted by Notarola View Post
    Im still looking for the info on the encryption for the MX. I have it burried somewhere but its a matter of finding it.
    Fingers crossed. That would be excellent. Thanks!!!!