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Advice Building Allstar/Echolink Simplex Node

Discussion in 'Echolink/IRLP Tech Board' started by K2HNL, Nov 8, 2018.

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  1. K2HNL

    K2HNL Ham Member QRZ Page

    I've acquired most of what I think is required to build a node but need to overcome one hurdle; and that is understanding the requirement or lack thereof for COS. I have purchased some Baofeng 888s radios, a SYBA SD-CM-UAUD, and I already had numerous Raspberry Pis. I have found a video on Youtube to modify the SYBA sound card but my problem is that the documentation on the repeaterbuilder website indicates that there is no hardware COS with this sound card. I'm not familiar with Allstar or COS and whether it is a requirement to make a simplex node.

    Can I just wire the sound card for PTT, audio in/out and wire that into the 888s? Or do I need COS to work on the sound card?

    Radio modification instructions:

    Sound card modification instructions:

    Sound card purchased:
  2. KA9JLM

    KA9JLM Ham Member QRZ Page

    COS is pin 48 (Volume Down) on the CM108.

    You can set a CTCSS tone in the 888 and set your node to use PL Tone instead of COS.

    Have Fun.

    Attached Files:

    Last edited: Nov 8, 2018
  3. K2HNL

    K2HNL Ham Member QRZ Page

    Unfortunately it's a CM119 based sound card. So there isn't an issue omittig COS? ImI still not totally clear on the function of COS with regards to allstar nodes. Is it being used just like PL to block out unwanted transmissions?
  4. KA9JLM

    KA9JLM Ham Member QRZ Page

    The CM119 is the same pinout, Just a newer chip.

    COS is used for a receiver that has a COS line, Repeater receivers can use it.

    The 888 does not have it, So PL is used in most cases.

    PL is used to stop interference from locking your node into transmit if squelch breaks.

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