2 Radios, 1 mic

Discussion in 'Microphones, Speakers & Audio Processing' started by K5LCY, Jul 27, 2020.

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  1. K5LCY

    K5LCY Ham Member QRZ Page

    So I have a Heil PR22 that I need to connect to a FT-950 and FT-991a. I have successfully connected it to the 950. I have a 8-pin to 4-pin adapter for the 950 and wired a 4-pin connector to the XLR cable. The mic works well on the 950 and I use the rear PTT with a switch to key the radio.
    On the 991 its a different story. I tried to use the 4-pin adapter I made from RJ45 ethernet cable but it did not work as wired for a typical 4-pin mic. I have tried to rewire the 4-pin plug on the RJ45 cable but I cannot seem to get the correct connection. Has anyone successfully built a connector for a 991 and a XLR mic?
    If I have to buy the Heil cable I will for the 950 but then can I use a simple 8-pin to modular adapter or will I have the same issues? I have limited space and I want to keep the wiring as short and simple as possible.
    Thanks in advance for any help you can provide.
  2. KA3NAM

    KA3NAM Ham Member QRZ Page

    Have you tried to make an adapter to go from the PR-22 to the 991a directly? The quick and dirty way to do this is to take the shield from the PR22 (typically pin 1 of the XLR) and connect it to pin 4 of the 991a mic connector (RJ-45). Then you can use either pin 2 or 3 and connect that to pin 5 of the mic connector of the 991a (RJ-45).

    Preferably I'd use a transformer or build a simple op-amp to convert from balanced to unbalanced.


    Attached Files:

  3. K1VSK

    K1VSK Ham Member QRZ Page

    Much easier to connect a key to two radios
  4. K5LCY

    K5LCY Ham Member QRZ Page

    Well thanks for the diagram, I was trying to use the wrong pin-outs.


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