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Wireless Microphones - what test gear can I use to diagnose?

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    Wireless Microphones - what test gear can I use to diagnose?

    I'm getting asked mote and more often to look at faulty Wireless microphones.

    I've already got several lying around at the workshop I don't know what to do with and I've been asked to look at two more in the last week alone!

    There seem to be a mix of UHF and VHF ones.

    Problem is I don't know how to go about diagnosing the faults. I have all the usual test gear for repair work , various meters and scopes etc.... but I can't even figure out the basics like how to determine whether the microphone is actually transmitting or if the receiver is not receiving.

    I can't even say with 100% certainty I'm being given the microphone with a matching receiver!

    Googling 'wireless microphone repair tutorial' didn't find anything useful.

    How do I go about repairing these?

    Rich
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    #2
    Re: Wireless Microphones - what test gear can I use to diagnose?

    you need to know the frequency's
    or intended frequency's - as drift could be the problem.

    get a frequency counter that is sensitive to RF from ebay/ali-express for 10€
    and if it covers the frequency's, a baofeng radio for another 20-25€
    a UV-6R or a UV-82.

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      #3
      Re: Wireless Microphones - what test gear can I use to diagnose?

      Thanks for the info
      I had a look at the Baofeng (both models) but they seem to specifically not cover the wireless microphone bands.

      From the internet i found the following (for Spain)

      Spain
      No individual license required / License exempt frequencies
      •30 MHz band, 50 mW ERP, 25 kHz, see IR-98
      •174.100 / 179.300, 50 mW ERP, see IR-99
      •188.100 / 194.500, 50 mW ERP, see IR-99
      •470 -786 MHz, up to 50 mW ERP, 200 kHz, see IR-216

      Note:-Secondary use. There should not be any interference to other emissions from the same band.-For use in public spaces, multimedia productions, artistic and sport events, of temporary character.-Compatible with TV service in the zone of use.
      •823 -832 MHz, 20mW EIRP hand-held, 100mW EIRP body-worn, 200 kHz
      •863 -865 MHz, 10mW ERP, 200 kHz, see IR-100•1785 –1805 MHz, 20mW hand-held and 50 mW EIRP body-worn
      •30 MHz band, 50 mW ERP, 25 kHz•UN36: 470 -786 MHz

      •UN118: 863 -865 MHz
      •UN119: 1785 -1805 MHz
      •UN48: 1785 –1805 MHz
      •UN-95, UN-106 and UN-127: 174.1 -194.5 MHz
      •UN151: 823 -832 MHz

      I'll have look for an RF frequency counter. Any suggestions for a good model to cover these frequencies? It has to be cost effective for the amount of repair work I am likely to get

      best regards
      Rich.
      Last edited by dicky96; 03-16-2019, 06:31 AM.
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        #4
        Re: Wireless Microphones - what test gear can I use to diagnose?

        the baofengs can go over a wider range than advertised.
        i'll try to find the details.

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          #5
          Re: Wireless Microphones - what test gear can I use to diagnose?

          I have a service monitor for this type of work, You might try one of those usb receivers like rtl2832 https://www.adafruit.com/product/1497
          with sdr software https://www.rtl-sdr.com/big-list-rtl...rted-software/
          Last edited by R_J; 03-16-2019, 12:17 PM.

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            #6
            Re: Wireless Microphones - what test gear can I use to diagnose?

            Winradio WR-G33WSM (in certain countries also available from SHURE) is the standard for wireless microphone spectrum scanning:

            http://www.winradio.com/home/g33wsm.htm

            Nick

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              #7
              Re: Wireless Microphones - what test gear can I use to diagnose?

              @R_J
              That looks like it will do the job of testing if the mic is actually transmitting and it's cheap too. Would the software tell me the frequency the mic is transmitting on (like a spectrum analyser) or do I also need an RF frequency counter?

              The link you gave me was for the USA. Although I live on the little spanish island of Gran Canaria, I usually pick up this sort of kit on one of my regular trips back in the UK as things cost more to post here and often go missing. Is this the same thing on ebay.co.uk? https://www.ebay.co.uk/itm/USB2-0-Di...frcectupt=true

              @N Salis - had a look at the Winradio but it seems to be around 100 times the cost of RTL2832!! That seems a really weird difference in price for two things what appear to do basically the same job. Unless I completely misunderstand what these two products do.
              Last edited by dicky96; 03-16-2019, 04:34 PM.
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                #8
                Re: Wireless Microphones - what test gear can I use to diagnose?

                There are different software available, some are free, and yes they can display the frequency like a specrum analyzer, I don't know how accurate it is but you could check it with a known transmitter, radio station, airport beacon etc.
                I have a rtl2832 a friend gave me, he used it to listen to air traffic and upgraded to something else.
                I think I was using sdrsharp software to try it out. and you can get different plugins for the demodulation etc.

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