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Long CW key and headphone cable, isolation? shielding?

BL7IB Member ✭✭
edited October 2019 in FLEX-6000 Signature Series
I am new to Flex6400.

I am going to make a cable to extend the CW key input and headphone output to another room.    The cable will run approximately 25 meters.    Should I choose shielded cable?   

Before I buy Flex I presumed shielding everything is good but another post recommend no STP (Shield Twist Pair network cable) to prevent ground loop.    

Should I build isolation circuitry to prevent RF get into the CW key input / headphone output?  (such as 4N35 optical coupler for CW / back-to-back diodes for audio)    or does FlexRadio already did this internally?


  • K9SO
    K9SO Member ✭✭
    edited October 2019
    Hi Rocky,

    I would keep it simple. I have my local radios in another room like you intend to do and run simple 8 conductor unshielded Ethernet cable to key my radios using a Winkeyer at the operating position. I have done this at more than one location and run big QRO at both QTHs with no problems.

    I'm close to 25 meters too ... you can always double up the unused pairs in the CAT-V cable if you're concerned about ohmic losses. . 

    I see no issue in doing this with three of the wires for direct use with a paddle either. 

    Headphone audio is fairly high level too so I wouldn't anticipate any problem with that.

    Low level Mic audio is a different story and would almost certainly need shielding. 


    Fred Glenn,
  • BL7IB
    BL7IB Member ✭✭
    edited October 2019
    Thanks for reply.   I am not QRO so I will try to build with simple unshielded cable.    

    Before I buy my Flexradio I played with another QRP radio that the CW key input directly go into the microcontroller without protection.     I believe it is not the case with this well-engineered radio.

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