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Thread: MTR 2000 VHF 100W out-of-band operation

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    Question MTR 2000 VHF 100W out-of-band operation

    So this website, http://www.repeater-builder.com/moto...0-900-mhz.html references how to move the 900MHz MTR 2000 into the amateur band.

    Thinking this might be possible for 150-174MHz 100W stations that have full coverage receivers but band stops in place on the transmitter, I used the above referenced modification to change the lower VHF band limit from 150MHz to 136MHz.

    To my surprise, it actually worked. The station produces rated power on 146MHz along with PL, however the transmit audio deviation is extremely low, and there is a lot of background noise and hiss.

    I would assume this is due to a lack of soft-pots and software deviation controls below 150MHz.

    I verified that the station does indeed work properly within it's "factory" bandsplit.

    Curious if any programmer types out there might want to take a look at the software and see if it's possible to move the alignment parameters of the transmitter further down in range.

    It's all done in the MPS.EXE file. It doesn't appear the software actually needs anything but MPS.EXE, it's a fairly simplistic, old Windows based program.

    It would be pretty cool to get these things working in the amateur band... A lot of surplus stations would suddenly become more valuable.


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    This is not the solution, but a contribution:

    http://batboard.batlabs.com/viewtopi...&hilit=mtr2000

    For those not BB members the essence was:

    VE3TUH modded his VHF high power, high split PA, tricking the station into thinking it is a VHF full band 40 watt PA as follows:

    Change R4560 from 1.5 K to 4.7 K
    Change R4564 from 1.5 K to 4.7 K
    It is a fine thing to be honest, but it is also very important to be right

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    As posted above:
    VE3TUH modded his VHF high power, high split PA, tricking the station into thinking it is a VHF full band 40 watt PA as follows:

    Change R4560 from 1.5 K to 4.7 K
    Change R4564 from 1.5 K to 4.7 K

    After that got posted on that other site, I was hounded by several guys who pretty much expected me to hold their hand through the mod.

    I agree re the 40 watts, I have a few repeaters out there (not all MTR) and run them all about 1/2 power. Have not burnt out a pa yet. I did allow the local radio shop into one of my sites once, and they kindly left one of my repeaters powered up, and unterminated. The circulator probably saved that one, as it was id'ing into an open for a few weeks. Was not too impressed with the radio shop.

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    mtr2000 pa.pdf

    ok, never done that. Board layout is attached as a pdf.

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    Presumably this follows the typical Motorola approach of a resistive divider on one of the A-D converter inputs with different values depending on the split.

    Could you please post the resistor values for the 132 - 154 MHz high power PA for those who are prepared to take a chance on the matching of the PA finals?
    It is a fine thing to be honest, but it is also very important to be right

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    Sure. R4560 and R4564 are both 15k, 132 - 154
    R4560 and R4564 are both 1.5k, 150 - 174.
    You shouldnt have any trouble, I would have done the mod this way and kept high power, but I have some needs in the commercial band too.
    Schematics are awesome things.

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    What would it take for you to scan that entire service manual as a PDF? *drool*