Z-100 interfare to ICOM

Discussion in 'General Technical Questions and Answers' started by K9FV, Dec 4, 2004.

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  1. K9FV

    K9FV Ham Member QRZ Page

    I just purchased the Z-100 for use with my 756Pro and would like to build a interface. I understand the interface offered by LDG for the tuner will allow one to power the tuner from the radio, and most important, this interface will cause the tuner to going into the "Tune" mode without pressing the "TUNE" button on the Z-100.

    Can anyone provide details on the wiring of the interface? The power part is easy, just the TUNE part I am not sure of.

    Thanks for any info,

    73 de Ken
  2. W9GB

    W9GB Ham Member QRZ Page

    Ken -

    The Icom 756Pro already has a built-in autotuner ..... and normally connects to the Icom AH-4 tuner (optional).  Every Icom transceiver, since the Icom 735 has a 4-pin Molex connector on the back panel for connection to the AH-4 tuner accessory.

    Your LDG Z-100 (manual)

    The LDG to Icom interface cable provides both DC voltage and control signals between the radio and the autotuner using the Icom's connector for the AH-4 tuner

    You need a "reverse engineer" from someone who purchased the LDG cables for your radio. (IC-2 shown), or read through the links below, pull out your VOM or scope and build the cable.

    AC-1 cable (power and signal splitter)

    Unofficial Icom AH-4 web page (for interface details to Icom radios)

    AH-4 electrical interface spec.
  3. K9FV

    K9FV Ham Member QRZ Page

    W9GB, you are correct, all I need is to get my hands on one of the interface so I can figure out they did it, then I could build my own. I was just hoping someone could provide this info, LDG isn't very forthcoming with this info 'cause they wish to sell their own.

    You are correct, the 756 does have an internal autotuner, and as ICOM says it will tune up a 3:1 SWR - not very good now is it? Most external autotuners will tune a 10:1 SWR - and that is why I went to an external. I've been using the SGC231, but the circuit board has a very bad spot on it - and to this point I've not been able to come up with a repair - yet.

    Thanks for any other help,

    Ken H>
  4. W9GB

    W9GB Ham Member QRZ Page

    Ken -

    As I said, all it takes is 4 wires (and the LDG photos of their Icom interface cables show this).

    AH-4 electrical interface spec (for the 4 pins on the back of your 756Pro).

    The electrical interface above shows these four connctions on the Molex connector (back panel of 756Pro)

    1 - Green: Key
    2 - White: Start
    3 - Red: +13.8 volts
    4 - Black: Ground

    Your LDG has 2 back panel connections:
    One is for powering the unit (does it run off 13.8 volts? - then pin 3 and 4 go here)

    The other "Radio Interface" connection likely uses one or both of the 2 signals (pins 1 and 2) from the 756Pro (key and start).  
    I will let you read all of these links (its your project, not mine), but intuition says .....
    "Key" to let you know that the transmitter is keyed and "Start" for starting the tuning process.

  5. K9FV

    K9FV Ham Member QRZ Page

    Thanks for the info gb.... BUT I'm just not sure if the LDZ is wired the same as the AH-4 or not. The SGC is not wired the same, and the molex plug on the rear of the 706 (and perhaps other ICOMs) can be wired with a couple of different accessories. One I've made for the 706 is to cause the radio to go into "TUNE" mode by pressing the TUNE button - this is an output of 10 watts CW for about 15secs depending on the value of the capacitor wired in.

    I was hoping the wiring was just a direct wire from the molex connector on the rear of the ICOM radio for the Z-100 LDG tuner, but was not sure.

    Thank you very much for the info - I had read those links before I posted the first question, but was not able to see clearly if it was direct wiring or not. Next week (I just got the Z-100 this Sat) I will call LDG tech support and see if they will give any info, or simply tell me to "Buy the LDG interface" - But like most hams, I'm a bit on the cheap side, PLUS I just take a certian amount of joy in "building in myself" type thing.

    Thanks again gb for you interest and help.

  6. W9GB

    W9GB Ham Member QRZ Page


    Here is the photo of the LDG adapter (IC2 + AC-1) for both control and power functions.

    See the 4 wires of the molex connector.  OK.  Then we have breakouts of the 2 conenctors.

    The power coax connector for the Z-100 (they must tie to pins 3 and 4 on the Icom molex connector)

    The radio interface plug is 1/8" stereo ... that is where the pin-outs are unknown (tip, ring, sleeve) to match up with pins 1, 2 and 4 of the Icom molex connector.

  7. K9FV

    K9FV Ham Member QRZ Page

    Now it's Monday and I was able to call LDG they pointed me to the website with the info for connecting the Z-100 to ICOM radios. Very helpful folks.



  8. W9GB

    W9GB Ham Member QRZ Page

    Ken -

    The Icom 4-pin plug information is on other web sites, but the "key" piece of informaiton was the Z-100 wiring
    for their radio interface connector [3 conductor 1/8" jack].

    Key #1 (tip); Start #2 (ring); Ground # 4 (sleeve)

    Good luck with it !

    73 de w9gb
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