Icom Handheld Dual-Band Radio Mod

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Introduction: Icom Handheld Dual-Band Radio Mod

This Instructable demonstrates how to modify a standard Icom IC-T7H hand-held dual-band radio transceiver to both receive and transmit on a wider range of frequencies.

Original:

2 Meter: 144.0-148.0 MHz
70 Centimeter: 420.0-450.0 MHz.

Modified:

2 Meter: 118.0 - 174.0 MHz
70 Centimeter: 400.0 - 470.0 MHz.

Hopefully this will be the first of many ham radio related Instructables I will post.

Side note:

This modification should only be made in preparation for emergency situations where communications out of regular ham bands are necessary, at no other time should an amateur radio operator transmit on frequencies outside of ham bands.

Step 1: Step 1, Disassembly

There are 10 screws that need to be removed to gain access to the internal control circuitry.

Four above the battery compartment

Two at the top of the battery compartment

And two at the bottom of the battery compartment

Remove these screws and set them aside carefully so they don't get lost or knocked around and then proceed to step two.

Step 2: Opening the Tranciever and Identifying D15

After removing the ten screws the radio should separate fairly easily into 3 parts,

The top "controller unit"

The back-plane "logic unit"

And the battery compartment cover which is just a piece of metal.

Next take a second to locate D15, a 3 pin diode in the lower right of the back-plane logic unit.

After locating the diode and checking out the rest of the awesome circuitry head to step three.

Step 3: Remove D15 and Reassemble

At this point you need to remove D15

There are many ways to do this and I'm no pro myself but I suggest desoldering the single pin on the bottom side of D15 and then simply using a toothpick or small instrument to lever it out.

Be very careful not to damage any other components in the process and use low heat on your soldering iron if you use one.

After you have removed the Diode reassemble the radio using the screws removed earlier and rest easy knowing in an emergency your radio can now reach out to a much broader audience.

Modifications such as this simply make your radio a more versatile tool, but keep in mind, like any modifications to RF equipment it is likely the FCC would frown on this unless used for emergency purposes by a licensed ham operator.

Until next time,

BlastwaveLabs

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    32 Comments

    I have safely completed this modification and I have to say, WOW! it works great! I had to buy a new Soldering iron to do the mod because the bit I had was not small enough to remove the component without destroying other components. I was able to modify three radios total. Thank you for the information and remember to abide by the rules of the FCC.

    hi friends..I bu aic-t7h mod...but this stop to send tx when a push the ptt. It receive normal..But dont transmit. When I push the ptt, I see that send sinal but not work microfone.

    how do i get a communicaty code coz i work on the doors in the uk in lancashire

    I have a baoefeng uv-5re...is there a way to modify it to receive cb radio frequencies? Thanks

    1 reply

    Nope. Since CB is in the AM spectrum between 26.965 & 27.405 MHZ and the ICOM handi talkie is 144-148 & 420.0-450.0 MHz FM, it would not be possible. They do make a CB handie talkie that is availablee for under $100.00. That would probably be your best bet.

    Established in 1989, as one of the core
    and leading manufactures of wireless 2 way radios.

    BFDX is the first group of wireless communication equipment
    research and development enterprise to integrate the hardware, RF, and software
    in China.

    tracy@bfdx.com

    www.bfdx.com

    This is legal in an emergency. Doesn't mean you may not need a lawyer but what jury will convict if you helped save life? Handsome boy BTW.

    Mike

    1 reply

    LOL I just talk to little kids on 462.562 megahertz running 50 watts with NO GMRS liscense, the kids arent gonna tell a difference

    Will this work on a Baofeng UV-5R? Would it be pretty much the same diode? I am getting 2 in a week for my friend and I. Also, someone said you wouldn't be able to hear people but they could hear you. Is that true? One last question following that. Would it work in close range to a network? E.g. our High schools frequency for maintenance is listed on a database, so if we were at school could we listen to them? or still would they only hear us?

    1 reply

    A baofeng already is unlocked, and will transmit and recieve from 400 to about 470 and 136 to 174 aprox.

    The baofeng uv-82 for a few bucks more additianally transmits and recieves on 400 to 520 megahertz

    You will be able to hear them and they will be able to hear you if you have the right frequency and the right CTCSS tone, which can be decoded on the baofeng

    Email me at electricity440@gmail.com for more questions

    if i do this i would be able to rx and tx on 160 to 161 MHz right. evn though it ould be illegal unless in an emergency i would still be able to right? another thing the pin you have to desolder is the one on the left side of the diode right? please reply' 73's KC2VDM

    1 reply

    This Mod opens up every freq that you can listen to on the receive section.
    With the proper length antennas you can transmit from 118-174MHz 2 meters
    and 400-470MHz 70cm. The whole 9 yards but better to stay in ham bands to stay legal.

    You could also put in a small spst switch in series with the diode. That would enable you to turn on/off the mod at will.

    3 replies

    Good idea definitely, that would prevent any accidental transmissions off band and keep the mod handy, instead of having to breakdown the radio to make the mod in some kind of emergency situation. Cool idea.

    There are memories to put the Freq's in that you use. To go into the VFO is ah deliberate act and very unlikely to have an accidental transmission that way. Short of some un-authorised person, accidental transmissions off band are not likely.

    Yeah but the insides are so tight there be no place to put the switch short of just letting it hang. Mod is done. Radio not broke. No need to add stuff.

    will this work on other icom radios also? like the IC A24?

    1 reply

    Any info on the theory of why this works or how you discovered the info?

    1 reply

    Probably they used the same boards for commercial bands, civil bands and ham bands. They just limit the bandwidth to suit their need and don't have to design and produce multiple boards. Emergency or not, FCC law states that at NO TIME is a ham to transmit outside the allowed bandwidth for any reason. It is a felony to do otherwise. My elmer (the one who helped me get my license) worked at a major radio equipment manufacturer with a gentleman who did that. That gentleman got 4 years in jail when he was caught. Where I live, we had a tornado knock the police, fire and rescue communications off the air for 72 hours. I am a ham with a local group that serve at the leisure of the regional emergency services. We were called to step in and provide communications. We used our radios, our repeaters and frequencies to fill their need. We rode with police fire and rescue in shifts for the entire 72 hours.