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flex 6400 with two mics

Gene - K3GC
Gene - K3GC Member ✭✭
Can two mics be attached simultaneously to my flex 6400.  I presently have a radiosport  attached ti the female 1/8 and a male RCA to the PTT .  I would like to add the HFM2 via a 1/8 splitter and the PTT.  Both mics would be attached simultaneously.  That way I would not have to be crawling  behind the rig every time I wanted to change mics.
Is this doable or am I about to enter feedback **** of one sort or another


  • Dan-N7HQ
    Dan-N7HQ FlexRadio Employee, Community Manager admin
    edited June 2020
    We would not recommend that method - there could be impedance and signal loss issues with a Y connection. 

    A far better method is to connect your microphones to a small mixer and send the output of that to the line-level input on your FLEX-6400.  There are a number of such products, but you will need to make sure they are not susceptible to RFI. 

    I use a mic preamp combined with a line-level mixer to accomplish what you are describing.  The line mixer has two discrete outputs that allow me to mix every device with an audio output to my shack speakers and two microphones + any other source to several radios.

    Dan, N7HQ
  • WK2Y
    WK2Y Member ✭✭
    edited June 2020
    And perhaps other might be able to recommend mixers that are not susceptible to RFI?
    Thanks and 73,
  • K0FLY
    K0FLY Member ✭✭✭
    edited June 2020

    I have not done what you are asking, but  I would try this approach,

    Connect FHM-2 (needs bias) to the MIC " input and the Radio Sport Mic to the "Line" input (accessory connector). 

    The mic connected to the 'LINE" input  will need an external  audio amplifier to bring the input  level up to -10dBv which is required by the radio.   Select which mic to use with SSDR.  Velleman kits makes a audio preamp that should increase the signal to  the required  level, it costs  $11 (Part number K1803).  

    The accessory connector also has a PTT input pin.

    Gayle K0FLY

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