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Thread: Motorola MTM800E RF Power Uplift

  1. #1
    Member Reputation: 21 AnRegs's Avatar
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    2012-11-19
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    Question Motorola MTM800E RF Power Uplift

    Hi all!

    I found out that MTM800E is very low power model, it's actually does 3W of RF or something. But PA MOSFT is powerful enough and consist driver based on MRF1518 and final based on MRF1535 (35W). I believe that radio can easily do 10W of power output as MTM5000 series.

    Any ideas what to hack in codeplug for this?

    Quotation from Service manual:

    The RF Power Amplifier consists of attenuator R5413, R5414, R5415, pre-driver IC U5401, driver transistor Q5421, and output transistor Q5431. The overall RF gain of the power amplifier string is fine tuned by the BIAS1 voltage from the controller, which is applied to VCNTRL pin 1 on pre- driver U5401. The BIAS1 signal is buffered by amplifier Q5501. The operating bias point of driver Q5421 and PA Q5431 is set by BIAS2 and BIAS3 respectively, buffered by Q5521 and Q5542.

    In codeplug I see PA_bias1_tune_table parameter and 8 softpots inside. Is it right place to play?

    Or I can switch entire power class of radio somewhere in codeplug internals?
    Last edited by AnRegs; 2018-07-13 at 03:46 AM

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  3. #2
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    Default Re: Motorola MTM800E RF Power Uplift

    If You will set too big bias current, You will blow the PA. Do You have service monitor that can measure TETRA radios?

  4. #3
    Member Reputation: 21 AnRegs's Avatar
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    Default Re: Motorola MTM800E RF Power Uplift

    Yes, I have TETRA service monitor. But there is no tuning technology is MTM800E DSM / BSM. Also, how can I blow the PA if I need only 10W when MOSFET can do up to 35W?
    Last edited by AnRegs; 2018-07-13 at 07:50 AM

  5. #4
    Member Reputation: 21 AnRegs's Avatar
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    Default Re: Motorola MTM800E RF Power Uplift

    Unfortunately, we were able to get only 4-4.2W of power output as maximum. PA_bias1_tune_table[x] and power_tune_table[x] were changed many times and in all places, but no luck with reaching 10 watts. I can suppose that Class 2 radios (10W) are HW different or Class # is set by some other unknown way. I was unable to find a place in codeplug where radio class is set, only some class for Data. And radio_class parameter what is already set to 2 in all fields (0/1/2), and as result, doesn't look like right thing to play with.

    Any ideas, guys?
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    Last edited by AnRegs; 2018-07-14 at 04:31 AM

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