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MFJ-1204 won't key PTT on IC-735

Discussion in 'General Technical Questions and Answers' started by W7GGG, Feb 14, 2020 at 1:24 PM.

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  1. W7GGG

    W7GGG Ham Member QRZ Page

    Hello All,
    I am new to all of this, I have a IC-735 that I picked up and just got a MFJ-1204D8, I am trying to use WSJT-X, everything is working except I cannot figure out how to get the 1204 to key the PTT on the 735. The audio is going to the rig, I can hear tone on the rig when I use the tune function., but it will just not key up. The USB speaker volume is turned up to 100%. I did open the 1204 and check the dip switches and checked continuity between block and din pin and everything is good. I just can't figure out what I am missing. Any help would be great.
  2. W7GGG

    W7GGG Ham Member QRZ Page

    Ok so the pinout in the mfj manual was wrong for the ic-735. I jumpered it correct and get the it to key and I can hear the signal but it's like it's not transmitting anything the s meter does not move at all. I also had to remove the mic since it doesn't mute it. Any thoughts?
  3. K7MEM

    K7MEM Ham Member QRZ Page

    I have a IC-735 and it works great for digital modes. Granted, I really only use it on PSK-31 and CW. My interface is all home brew and I attach through the rear ACC(1) connector.

    It wasn't clear to me whether you use the microphone connector or the ACC(1) connector. The details of my interface are on one of my Web Pages. Maybe the connector pin outs can be of some help.

    Your symptoms suggest that audio is not getting to the right place. It's easy to put the IC-735 into transmit, but without audio, there isn't any output. Also, when you are in the transmit mode, the meter is showing power out, or the lack there of. It's only a S-Meter in the receive mode.

    There are a few things you need to know about the IC-735. First, if you use the ACC(1) connector, the VOX is bypassed. This can cause a problem for software that relies on the VOX. The VOX is only available through the microphone connector.

    Second, I forgot what the second thing was. The third and fourth thing too, probably. It will come back to me in time. Isn't getting old fun? Always a new adventure, all over again.
  4. KP4SX

    KP4SX Premium Subscriber QRZ Page

    Oh, I remember that second thing all to well. :oops:
    W7GGG likes this.
  5. W7GGG

    W7GGG Ham Member QRZ Page

    Thanks. I figured it out. Even though I had to re pin since the mfj manual isn't correct for the 735 I had the mic and speaker reversed so I got it working now.

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