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Discussion in 'Radio and Communications' started by MwapeM, Nov 27, 2015.

  1. MwapeM

    MwapeM New Member

    Nov 4, 2015
    Help me on my stations RVR transmitters. Allow me to give detailed information here.

    The first transmitter was reported faulty by showing zero forward power on the display and low signal close to transmitter with no signal 50 meters away. When checked, we physically saw that the combiner resisters at the RF output were burnt.

    The second transmitter was reported faulty by having only signal close to the transmitter. When checked, the forward power was zero on the display. Checking the parts also showed burnt output resistors.

    I suspected even the output mosfets were bad also. I tried to do some on circuit testing using voltmeter. My observation was that the mosfets are supplied with 50 volts dc. two mosfets in one transmitter showed full 50v on both sides where as one showed 1.5V. This to me suggested either those showing full voltage are faulty or the one dropping the voltage. The other transmitter is showing the opposite. It has two mosfets dropping voltage and one showing full voltage.

    So I am thinking of getting all the RF modules with full voltage in one transmitter and those with 1.5 v in the other. What do you say. Also can the transmitter work without the combiner resistors. Help me repair these transmitters.

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