Yaesu MD-100 Desk Microphone & Yaesu FT-7900R

Discussion in 'Microphones, Speakers & Audio Processing' started by WA2NWN, Dec 2, 2019.

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  1. WA2NWN

    WA2NWN XML Subscriber QRZ Page

    Hello all,

    Have an odd question regarding using a Yaesu MD-100A8X Desk Microphone which is an 8 pin microphone. I currently use it fine with my Yaesu FT950 HF rig but find myself talking more on local repeaters. For 2m/440 I use a Yaesu FT-7900R with an MH-48 mic which is a six pin RJ12 connector.

    I am curious if I bought an adapter if I could use this MD-100 desk mic with the 7900R? I have found a nice website with a ham that makes all kinds of adapters for anything ham radio related. Only thing him and I could not figure out is if the voltage will be an issue. I attached two schematics below- the MD-100 uses 5v and the 7900 radio puts out 9v. Too me, that sounds like an issue. I do not care if the scan button on the desk mic works. Looking for some input.

    The link for the adapter is below:

    Thanks - WA2NWN

    Attached Files:

  2. WA2NWN

    WA2NWN XML Subscriber QRZ Page

    On a side note, this is my first post to the forums looking for help. I checked off the box to be notified by email- so I will see if that works. If I do not respond here my email is my callsign at gmail.com.

    Thank you!
  3. KD0RCB

    KD0RCB Ham Member QRZ Page

    If you look at the schematic of the mike below, youll see that in the THRU mode, the active circuits are not used, (they're bypassed) so the 5v B+ is not needed. But in the FILTER mode, the op-amps need the 5v to power them properly. I would think that applying 9v would either damage them, or severly shorten their life, if they work at all. If they short, they could then damage the 9v supply in your radio, too. You would have to wire in an external 5v source , to use the filter setting without damage.

    Attached Files:

  4. WA2NWN

    WA2NWN XML Subscriber QRZ Page

    Thank you! I agree with your statement.

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