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3.5mm microphone cable extension

Mike VisichMike Visich Member
edited April 7 in SmartSDR for Windows
Looking to extend my 3.5mm 2-Pole microphone cable from my HEIL Pro-Set Plus to my 6400.  Was thinking of the following 3-Pole extension found on Amazon.


The manual makes the following point about the headphone jack - CAUTION: Do not use a mono (TS) plug as this will short-circuit the right channel signal to ground.

Assuming there is no problem for the microphone, but better to be safe than sorry!

73 Mike 


  • edited March 25
    Something to think about there is a lot of space under the radio to run your cable . I was going to do the same thing until I found that out that it gave me enough wire image
  • Ha GeiHa Gei Member
    edited March 25
    The mic is mono anyway. The shorting  issue has to do with distributing slices to left/right ear

  • James SkalaJames Skala Member
    edited March 25
    I wish I could find a over the counter computer headset that I could use some sort of y cable to the flex 6400
  • Logan KE7AZLogan KE7AZ Member ✭✭
    edited March 25
    My 6600 sits in a re-purposed TV cabinet (from the old days when a 32" CRT TV was a 'big screen'.  Cabinet cost twice as much as the TV.) next to my computer/ operating desk. I used the AmazonBasics version of this cable to extend Mic, Headphone, Key, and PTT to my desk.  I labeled the wires on both ends to make it easier to keep track.  Tie wraps keep the wire bundle manageable. I route the bundle to a desk side drawer and use the "curly Q" Heil cable to the headset.  When done, it all tucks into the TV cabinet, the doors are closed, and the ham radio station "disappears."
  • Toby PayneToby Payne Member
    edited March 26
    a Stereo 3 pole commonly known in audio world as "ring tip sleve" will work on the mono connection you are using. The use of a tip / sleve Mono connector in a stereo jack will short the ring to ground which is the sleve. That is what the warning is about.
  • Mike VisichMike Visich Member
    edited March 25
    Thank you ALL!
    I'll order the cables.

    Stay Healthy & hope to see you on CQ World Wide WPX this weekend!

    PS:  I have one of the TV cabinets.  It's now a coat closet! 
  • KD0RCKD0RC Member ✭✭
    edited April 7
    You cannot plug in a two pole jack into the mic connector on a 6400.  You need a 3.5 mm (1/8 in) TRS (aka stereo plug) wired as follows:

    Tip = mic+
    Ring = mic -
    Sleeve = Ground

    Len, KD0RC
  • LarryLarry Member ✭✭
    edited April 7
    My Heil Pro headset with the condenser mic (requires bias voltage) has a two pole tip/sleeve male plug. It plugs directly into the mic female connector on the back of my 6400 and functions properly.

    I know the hand mic that shipped with my radio had a Tip/Ring/Sleeve connector.
    I was not able to find a good answer in the manual as to if the mic input connector on the 6400 (not M model) is 2 conductor or 3 conductor connector?

    Larry - KB5WWW
  • KD0RCKD0RC Member ✭✭
    edited March 26
    Ah, good to know.  Grounding the mic(-) line must be OK to do.  The mic connector on either flavor of the 6400 is a 3 conductor jack. From the hardware manual:

    The MIC connector accepts a 1/8-inch (3.5mm) stereo (TRS) plug and provides a pseudo-balanced microphone input. Pseudo-balanced means that the mic (+) and mic (-) lines are balanced all the way to the input of the A/D converter, where the mic (-) line is DC grounded. The connector may be used with dynamic or electret microphone elements. A software enabled 3V bias voltage through a 2.1k Ohm source impedance may be applied to the Mic (+) line for electret microphones.
    Note: The PTT signal is not accepted by this connector.

  • KD0RCKD0RC Member ✭✭
    edited March 26
    My first statement is apparently not correct, see response below.

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