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IC 551 PTT via Serial Port

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  • captcurt2000
    Hi All: I would normally not want to post a hardware related question here, but have gotten nowhere on the icom pages. I am trying to set up my Icom 551 for 6M
    Message 1 of 1 , Dec 4, 2009
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      Hi All:

      I would normally not want to post a hardware related question here, but have gotten nowhere on the icom pages.

      I am trying to set up my Icom 551 for 6M MS ops via WSJT. I use an interface for all my other radios that operates the PTT lines via an opto-isolator directly in the PTT line to ground. My small Kenwood FM rigs, Drake twins on HF, the TS-700s all work fine this way. It requires no external power to be applied to the interface box.

      The IC551 will not go into transmit this way. It appears that the opto won't actuate the relays in the ic551 directly. So I added a Darlington-connected output transistor after the opto. It too works fine with all the other radios but not the 551. THe only difference with the Darlington set-up was the transmit light would actually turn on in the radio but the relays still wont switch.

      Before I go to the trouble of adding a powered relay in the interface box to get contact closure, is someone using anything similar with an IC-551 they can share the method that works?

      THanks

      Curt
      KU8L
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