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ICOM IC-746PRO MARS Mod

Discussion in 'Radio Circuits, Repair & Performance' started by K3WVU, Mar 5, 2008.

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  1. K3WVU

    K3WVU Ham Member QRZ Page

    Just bought a new 746PRO and did the MARS mod by removing the W1603 and W1604 jumpers. No problem with the HF MARS frequencies, but now it won't transmit about 146 MHZ (which is the European limitation). Has the MARS mod changed for the newer versions of the rig? I'm waiting for a reply from ICOM, but I wondered if anyone else had run into this.

    Oh yes, in case anyone is wondering, I am a Navy MARS member.:confused:

    73

    Dwight
     
  2. W0LPQ

    W0LPQ Ham Member QRZ Page

    Did you perchance, ask your MARS director about the mod, maybe he has different info?

    No idea. Have a Pro II and will never mod it ... dropped MARS years ago. I do know that some Icoms when you do the mods, will kill the band edge beeps and some presets and repeater offsets.
     
  3. K3WVU

    K3WVU Ham Member QRZ Page

    It's the correct mod

    ICOM is as perplexed as I am. They said that somehow, the matrix has gotten changed. It's off to ICOM for the rig. $$$$$$$$$$$$$$$

    I've performed the mod on about a dozen or so ICOM and other rigs. This is the first one that gave me any trouble (it also has smaller smd jumpers than any of them, including an ICOM IC-T7H).

    I guess I keep using my trusty ol' 718 until we get the sexy new 746PRO fixed.
     
  4. NN4RH

    NN4RH Subscriber QRZ Page

    This has got to be a first for this forum! A MARS mod by an actual MARS member! What will they think of next? ?
     
  5. K3WVU

    K3WVU Ham Member QRZ Page

    Yeah, no kidding. I've sold some MARS modified stuff on Ebay, and invariably, I'll get questions like: "does it do 11 Meters". I usually answer that operation on 11 Meters activates a built-in ID signal that the FCC can track. Of course, none of these morons will bid over $100 anyway.
    The second most common question comes from EMTs or firemen who want to know if the rig operates on their public service frequency. When I tell them that the equipment is not type accepted for use there, the usual response is ,"that's OK, I'm authorized to transmit on those frequencies. Again, none of those guys ever bid; they just ask questions.
     
  6. WA9SVD

    WA9SVD Ham Member QRZ Page

    SOME of them do NOT know better; they aren't radio-literate or FCC rule-literate. I see no problem with answering them truthfully and honestly, as you apparently do.
    The problem comes from those so informed (or should already know better) insist they have every right to use modified equipment on other than Amateur frequencies.

    I suppose they DO have the right.

    They also have the right to remain silent, to appear before an FCC adiminstrative judge, to pay an NAL...
     
  7. WA9SVD

    WA9SVD Ham Member QRZ Page

    Sorry if a legit mod went wrong. That's why it's best to submit your MARS documents and radoi information directly to the manufacturer, to ensure accurate and up-to-date information and instructions. As all the manufacturers state, they reserve the right to make modifications at any time. Production methods may indeed entail a physical modification to circuit boards, so "old" instructions for a year, or two years, or even ten years ago may not apply to the radio purchased today.
    Good luck. Hope it's a simple fix.
     
  8. W0LPQ

    W0LPQ Ham Member QRZ Page

    Larry, your comment about manufacturers making changes to radios reminds me of one our old VHF-20 Airborne VHF/AM transceivers. This radio is now long out of use and cannot be used for overseas flight ... but we made several changes (mods) to the synthesizer, due to parts going obsolete. At one point we had to completely relayout the circuit board. That was a real bear, since the space constraints on the original board made it very difficult to re-engineer a new board ... parts did not get smaller, but the major SMO chip got larger from the manufacturer..!

    Everyone who makes this stuff, makes mods down the road as parts become obsolete and they try to re-engineer new chips to do the original function. Aviation has the added expense of recertifying the changes.
     
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