Wednesday, 18 May 2016

Yaesu FTM-100DR wideband TX modification

If you've been keeping up with my blog you'll know I have one of these radio's. So far it's been a great radio for the money (I got it on sale at HRO for less than $300). I need it to transmit on some none Ham frequencies and so need to modify it so that it will transmit out of the Ham bands. This modification is commonly knows as the "MARS/CAP mod".

There's nothing new under the sun and certainly not on the Internet so that's where I went looking first. A Google search led me this document which outlines the modifications for both the FTM-400 and FTM-100 radio's. It's wrong!!!!

Or rather, it's not quite correct. Whilst the document correctly outlines the modification procedure for the FTM-400 it only outlines the procedure for the European version of the FTM-100DR. It's all about removing the resistors y'see. Using the pictures in the above document I noticed that the EU resistor was already removed in my radio. Erm ..... WTF? So it does appear that the modifications for the 400 are the same as for the 100.

Original picture from here

Take the top cover off your radio and orient it with the mic socket facing you. In the bottom left will be a white sticker with a slot in it for the firmware upgrades. Carefully remove the sticker to reveal the backup battery and a screw as above.

If you have an EU version the resistor that would be removed for the US version is already missing. The same is true in reverse for the US version. In short, you will remove the relevant resistor so that in the end you will have no resistors in either the EU or US position. My US version already had the EU resistor removed so all I had to do was remove the US resistor.

Click on the above picture for a better look at what to remove. The usual caveats apply; I won't be held responsible for your bad soldering work. If your car explodes when you key up on your local CAP repeater that's your lookout.

The radio will reset itself when you first power it on. You'll need to make sure that either you back it up before carrying out the mod or somehow reprogram the radio when you turn it back on again. This part is still causing me issues but that's another story.

###### UPDATE 20160518 ######

Reprogramming the newly modified radio is a bit of a nightmare. All of your saved memory files will no longer work. I tried to restore the radio memories etc from the backup I had made to its SD card but the radio displayed an error whenever I did it.

The fix was to move the SD card to the laptop running the programming software. I read the SD card into the software then saved it as a CSV file. Returning the SD card to the radio I formatted it and then performed a backup to the SD card.

I then returned the SD card to the laptop and read card in again. Now that I had an active file I "Inport" (there's lots of spelling mistakes in the Yaesu software) the CSV file and then send all the data back to the SD card. Finally I moved the SD card back to the radio and read in the memory information. The radio rebooted when it was done reading the file and there were all my memory channels restored.

Why didn't I use the programming cable? This is gonna sound silly but you need 2 people to do this when you remote mount the radio. I couldn't set the radio to clone mode and then run to the trunk to press the buttons on the laptop before the radio timed out. I'm sure this would have been a less painful way to reprogram the radio. Maybe next time I'll enlist some help?


  1. What is the new TX frequency range?

    1. The usual 138-174/400-512MHz. I don't make any claims as to how good it is out of the ham bands though.

    2. if this worked for you, I would very much like to know the manufacturing date of your radio, as I am trying to figure out the approx. time yaesu changed this radio in such a way that this no longer works. This method on a 2016 or newer ftm100 or 400 will result in region error.

      also I would like to know if you had programmed a region INTZO the radio prior to doing this modification? perhaps that has something to do with it.

  2. Dont want to be a pain in the ass, but can you confirm TX up to 512MHz?
    Am particularly keen on being able to TX @ 477MHz
    Some radios stop at 470MHz when modded.

  3. Nope. I cannot confirm this. And even if it did generate RF at those frequencies it would probably be pretty low power and also deaf on receive.


  5. It will not let me into menus... it shows region error where the call sign usually is on power up and just stays on that screen. I could send you an email with a pic.

  6. Did you figure out a solution to the "region error" message? My radio is doing the same thing

  7. No I have not.... can't find any documentation in it either... as of now it's still a brick... if you figure something out please do tell... thanks. Devan.

    1. ************
      Can't seem to spell my own name

    2. Did you try replacing the resistor you removed?

  8. Wow, it's a pain to re-program the first time.... I had to to little different than yours. first upload after back up, import etc. had to be with just one frequency in memory.... when I got that in, now I can write on the sd all memories, still no connection with cable to PC for some reason.

  9. I have this japan Version ftm-400xd. I remove & it's region error. I installed again and back to normal. Any others suggestions to modify the tx below 144mhz (

  10. this is obviously NOT a correct way to mod these radios. I did the exact same process and also received the region error on my ftm-100dr japan made radio. this documentation should be removed, its only bricking radios, and not too many people can probably solder or replace such a TINY resistor back in place.

    for those that can, it's only a 0 ohm resister put in place as a "place holder" solder, wire, or whatever method you can do to make contact from one side to the other of the resistor points, and the radio should work again.

    Hope this helps....

  11. I love it when people do NOT read all the info before proceeding to mod their gear. Then crying when it does not work.

    I quote the following from the instructions,

    "Or rather, it's not quite correct. Whilst the document correctly outlines the modification procedure for the FTM-400 it only outlines the procedure for the European version of the FTM-100DR"

    Again it is for the EU radio! NOT the US version

    By NOT fully reading ALL the instructions you are always taking the risk of bricking any gear.


  12. There are 3 resistor locations to confirm when doing this mod. There are two resistors close to each other- near the battery + terminal, close to the edge of the board. If you have a US version and remove the resistor such that there are no resistors installed either of these locations, you will get a region error. For the US version, you must leave the resistor installed that is the closer to the battery (of the noted two). It is the third resistor that is removed on the US version. This is the resistor marked "remove for us version" in the pic. it's the one just 'north' of the + symbol on the pcb.