Icom SM50 schematic

Discussion in 'General Technical Questions and Answers' started by N9ALE, Sep 16, 2021.

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  1. N9ALE

    N9ALE XML Subscriber QRZ Page

    Does anyone have a readable schematic for the Icom SM50 microphone. The ones I find on the web are of such low resolution as to be unreadable.

    Thanks
    Jon
    N9ALE
     
  2. W9GB

    W9GB Ham Member QRZ Page

    BD72825F-F5E6-47A8-B85C-D318489FB32F.jpeg
    Jon -

    Since the Icom SM-50 is a current production microphone,
    you just need to download from Icom (Japan) Support !! (I also attached the PDF)
    https://www.icomjapan.com/support/manual/1608/

    Icom America : Knowledgebase Support
    http://icom.custhelp.com/app/home
    Icom SM-M50 Stand Microphone Instructions (Icom America)
    http://icom.custhelp.com/app/answers/detail/a_id/2440/kw/sm-50

    Icom SM-50 Stand Microphone Instructions (Icom Japan)
    https://www.icomjapan.com/uploads/support/manual/download/SM-50_JE_IM_2.pdf
     

    Attached Files:

    Last edited: Sep 16, 2021
  3. K7MEM

    K7MEM Ham Member QRZ Page

    Jon,

    The only schematic I found was on IZ0HCC's web site. If you click on the schematic, it is opened in a bigger window and then can be expanded. Even then it's not very clear, but I saved the expanded schematic to disk and then opened it in IrFanview. In IrFanview, I blew it up to 200% and then ran a sharpening filter. This brought out all of the annotation. I can read all of the reference designators and parts values. To me, the schematic is clear enough. Is that good enough?

    Or, you could email IZ0HCC and see if he has a better copy. His email address is on his site.
     
  4. N9ALE

    N9ALE XML Subscriber QRZ Page

    Martin,
    WOW, Thank you so much. I really appreciate your help!
    I hope to catch you on the bands some time.
    Jon
     
  5. W9GB

    W9GB Ham Member QRZ Page

    Agree, the notations are not sharp.
    Electret microphone pre-amplifiers fall into three (3) main categories:
    • Bipolar junction transistor (BJT), discrete circuit
    • JFET, discrete circuit
    • Op-amp circuit, like OP172
    The FET and follow-on BJT (pre-amp) was very common for 20th century designs,
    found in numerous amateur radio magazines (QST, CQ, HR, 73) as well as Handbooks.
    ==
    In recent years, Op-amps like the Texas instruments OPA172 has become popular.
    https://www.ti.com/lit/ug/tidu765/tidu765.pdf
    Electronics Lab
    https://www.electronics-lab.com/project/low-noise-mini-electret-microphone-preamplifier/
    78B2584F-8C69-4A8A-8BFC-0AE30CC4A28A.jpeg
     
    Last edited: Sep 25, 2021
  6. N9ALE

    N9ALE XML Subscriber QRZ Page

    Thanks for the links. The Electronics-lab site looks very interesting.
     

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