706: Frequency Expansion

© 2003-2011 by Harold Melton, KV5R. All Rights Reserved. Rev.06/11/05

Shop for Icom radios here.

Frequency Expansion Mod for the Icom 706MkIIG

This modification will allow the MkIIG to transmit on most of the frequencies that it receives on.

Notes:

  • The author does NOT advocate any illegal operation. It is YOUR responsibility to stay within your authorized bands.
  • This is for the MkIIG ONLY. Earlier models use an entirely different procedure.
  • This procedure will RESET the radio to a factory-new condition. All memories and settings will be cleared. Write everything down first!

It is useful for:

  1. Accessing the Amateur 60-meter channels
  2. Authorized MARS and/or CAP operation
  3. Unauthorized operation on any frequency, only in immanent life/death emergency, only when no other means of communication are possible (legal but still legally risky)
  4. NOTE: Amateur Radios are NOT FCC TYPE-ACCEPTED to operate in other services — even if you have the license to do so! Don’t goof around in the legal gray area unless your leg is mashed under an 11-ton boulder! Remember that other (non-Amateur) radio services require not only a license, but also a radio that is FCC Type Accepted for that service!

Tools: The 706 uses components that are extremely tiny. You will need at least the following tools:

  1. 2.5x to 3.5x headband visor magnifier or jeweler’s loupe
  2. Bright light
  3. 15 watt pencil iron with a clean, lightly tinned, needle sharp point
  4. Fine-point tweezers
  5. Extremely steady hand

How to remove it (D2030):

photo
MkIIG ONLY - Top PCB - Red Arrow Indicates tiny SMT Diode to Remove.

  1. Some people just crush it with needle-nose. I don’t like that idea since it might damage the PCB.
  2. Take the tip out of your 15-watt iron. Chuck it in a drill. Turn it against a grinding stone, to a needle point.
  3. Reinstall the tip. Heat and re-tin it. Tap off the excess solder.
  4. Remove power cable from radio. Remove top cover slowly. Carefully unplug speaker.
  5. Using visor magnifier and bright light (and a very steady hand), catch one end of the diode with tip of iron (very lightly tinned).
  6. Gently pull upward with the iron. The diode will either rotate upward on it’s other lead - or it’ll break off.
  7. If you lift one end just a little, you can leave the diode there in case it ever needs to be reattached.
  8. Plug in speaker. Reinstall cover. Power up. Reprogram all your memories and settings. 

photo
The removed diode. The rod is a 0.5 millimeter mechanical pencil lead.
You can see the diode is about ¾ x 1 millimeter.


Disclaimer: The author assumes absolutely no responsibility, under any circumstances, for what the reader may do with this information. Building and connecting circuits, and performing adjustments or modifications, may damage your radio, void your warranty, and/or cause it to operate in violation of FCC rules and Type Acceptance, etc, unless you are very careful.

Continued…

14 thoughts on “706: Frequency Expansion
  1. Hi, nice jop thank you for it , i own icom 706 mkiig worked very will suddenly stop tx on hf all band tried to restarted no reaults, opened covers to see if there is any burns all components all clean , due to no work shop in my land , if you have any ideas it will great, by the way v/uhf working good .
    Waiting your advice,.

    73j

    • Probably either blown HF finals, or bad relay on filter board. Could be many many other things; an oscillator, RF driver, filter switching diode, etc. You’re gonna need to ship it to an Icom service shop, or sell it for parts and get another one.

  2. I am a commercial pilot and General class radio operator, and a dream of mine is to solo fly across the Atlantic, and I would definetley use an IC 706 onboard the aircraft. Can you please put up this info?

    • Put up what info? The mod in this article will allow 100w transmit in the whole HF band, you can use it (the 706) in int’l airspace/waters.
      Be careful/aware of jurisdictional restrictions.

    • Hello,
      The 706 has a general coverage receive from .03 to 200 MHz plus 400-470. You should be able to receive HF marine frequencies without any modification. Only the transmit is limited to the amateur bands.

      • ok, thanks, I was thinking that maybe there was a mod that can be done so this 706Mkiig could TX on frequencies similar to the Icom M802 Marine SSB radio ? Like 8 mhz area. Like these,–8.104 USB Seven Seas Crusing Assn. or Cruiseheimers Net USB on 6.516 / 6.224 / 6.227 / 6.230..

        • This article describe the mod in detail. Just be aware the radio is not FCC Type Accepted for transmitting in other (non-ham) radio services, so unless you’re gonna be in international waters… don’t risk it.

  3. Good morning,
    Thanks a lot for the information.
    I would like to open my Icom 706mkiig to the marine frequencies but on my radio the diode is missing.
    Any suggestion?

    • If all diodes are removed from that strip it’ll transmit on all freq except wfm broadcast band (88-108) – tho some parts at very low power.
      Looks like it’ll do vhf marine frequencies OK, but remember it’s not type-accepted for that.

  4. Hi! I need to expand Tx to 143 Mhz for my ICOM 706 MK2G but diode 2030 is missing! My 706 is coming from Japan ! Another method to get to 143 Mhz ?
    Thanks!

    • I was talking about transoceanic aviation, which uses SSB on HF aviation frequencies. Only the VHF aviation band uses AM.

      Anyway, I removed that section because nobody’s gonna use a 706 on transoceanic aircraft.

Leave a Reply

Your email address will not be published. Required fields are marked *