No side tone on handheld radio with Lightspeed headsets

Discussion in 'Avionics and Upgrades' started by bkspero, Nov 6, 2018.

  1. bkspero

    bkspero Pre-takeoff checklist

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    Looking for help with an odd problem. I just got a new Rexon RHP-530 Com handheld radio. It comes with a headset adapter cable for use with aviation headsets having the standard 2 plug connection. The radio has side tone which the manual says is automatically activated when the headset adapter plugs are inserted into the radio sockets.

    Surprisingly with I tested the radio with my Lightspeed Zulu 3 headset it had no side tone. It broadcast and received fine, but I could not hear my voice during broadcasts. So I tested it with 3 other Lightspeed headsets and got the same results (a Sierra, a QFRXCc active noise reduction headset, and a QFRXC passive noise reduction headset). Next I tried an ASA HS1A PNR headset and it worked normally (got the side tone)!. After that an old Sigtronics headset and it also produced side tone???

    I called Gulf Coast Avionics, who sold me the radio, and they tested the same model radio with headsets from Lightspeed, David Clark, and Bose. No side tone with the Lightspeed and normal side tone with the DC and Bose. The radio works great with any headset not made by Lightspeed.

    Neither Gulf Coast nor Lightspeed could explain how this could be. So I am reaching out for help to POA. Anyone seen this before? What are possible causes and fixes?

    BTW, the radio has a side tone volume adjustment. I tried the full range of settings with my Z3 and it had no effect. I also tested with the headset switches in both Stereo and Mono. No change other that in Stereo there is only sound in one ear cup.
     
  2. wanttaja

    wanttaja En-Route

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    When all you have is a hammer, everything looks like a nail, so....

    I'm guessing it's something to do with the headset audio impedance. The Rexcon has an output impedance of 4 ohms. Standard aircraft headsets run 150-300 ohms, and the "adaptors" don't correct that.

    I'm speculating that the sidetone audio is more sensitive to impedance mismatch, for some reason. Wonder if the Lightspeed runs towards the top of the allowable range.

    Two solutions would be to either switch headset brands or build an impedance matcher....

    http://www.bowersflybaby.com/tech/amplitude.html

    Ron Wanttaja
     
  3. Ray Eaker

    Ray Eaker Pre-takeoff checklist

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    I don't have that headset but have used others with my Yaesu handheld and never heard side tone.
     
  4. Scrabo

    Scrabo Pattern Altitude

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    I have the JHP version of the Rexon and a Zulu 3 , I can check later, also have an old softcomm set somewhere. Also have a Yaesu handheld and can do some research
     
  5. bkspero

    bkspero Pre-takeoff checklist

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    Just looked over the notes from my testing and I have to correct my original information. I got no side tone with my Zulu 3 and my Sierra, but I did get side tone with my old Lightspeed QFRXCc ANR and QFRXC PNR headsets??? Repeated the tests today just to be certain, and confirmed those results.

    I also have an old Yaesu radio (was Vertex when I bought it), and while it doesn't transmit consistently when a stereo capable headset is attached (one with a TRS headset plug), it does provide side tone when it transmits (either with any Mono (TS headset plug) only headset or when the stars align just right with a stereo capable headset).
     
  6. Ryan F.

    Ryan F. Line Up and Wait

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    I don't get side tone with my IC-A23 and Bose A20, or Zulu 2. It seems to just be the way they work. But I have an old radio and an old cable. Who knows.
     
  7. Ray Eaker

    Ray Eaker Pre-takeoff checklist

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    Switching the HS to mono might help.
     
  8. bkspero

    bkspero Pre-takeoff checklist

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    Thanks for the suggestion, Ray. I thought the same thing so when I tested the headsets I did it both in stereo mode (those capable of stereo) and in mono mode. Since the radio is a mono source, operating the headsets in mono mode caused sound to emanate from both earpieces while operating in stereo mode caused sound to come from only one earpiece. The stereo/mono setting had no effect on the presence or absence of side tone.
     
    Ray Eaker likes this.