IC-7600

I don't think I really have to say this, but update the firmware on your IC-7600 if you have an older unit.  The one that I picked up used had the original firmware on it and I was amazed how many new features (especially the waterfall) were included in the update.  Updating the firmware on any device is usually a good idea, but this one in particular was a big improvement.

Full disclosure here, I haven't done this mod on this radio yet.  I have opened up all of my other radios, but this is still on my to do list.  There are lost of reasons to do this modification.  My biggest reason is that in the event of an emergency, I want to be able to transmit on whatever frequency I need.

The 7600 is pretty simple to modify.  You will have to disassemble the unit slightly, but not very far at all.  First, you will need to remove the top and bottom covers and the handle.  You will then find four screens holding the front panel on the unit.  Remove those screws and lay it down gently (be careful of the ribbon cable!).  Remove the metal cover on the back of the face plate.  It is held in place with five screws.  

Now, with the metal shield removed, remove D59, D58, D57, and D56 for full TX coverage.  Remove D52, D53, D54, and D55 for full RX coverage.  D51 must always remain.  If you are unsure which diodes are which, please verify  before you start removing.  While it's possible to put them back if you mess up, it's certainly not easy and adds more chance of damage to the radio.  There are pictures online and videos on YouTube of  this process.  If you are still unsure, I'd be happy to help in any way I can.  

When done, reverse the process of disassembly and you're done! 

The 7600 doesn't have an IF output and the communication via USB is too slow for any kind of live waterfall display.  The radio does, however, have an IF signal that goes from the main unit to the RF unit that we can tap into.  You'll have to remove the cable that runs between these two connections J2001 and J6001.  As always, double check you are looking at the correct cable.  The nice part here is that this is easily undone by just plugging it back in.

The connectors inside the radio are TMP connectors.  I don't know about you, but I don't have any of these laying around and I didn't feel like buying connectors and a crimper to match so I found some TMP to SMA male cables on eBay.  You'll need two of these cables for this project.  Plug the TMP connectors on each board and run the SMA end outside the case.  You can drill new holes for these cables or run them next to an existing opening if there is enough space.  That all depends on whether you want to be able to fully reverse this process or not.

On the back of the unit you will need some kind of splitter.  Most people recommend the Mini Circuits ZFSC-2-1-S+.  I have on on order so I will update when I have this completed.  Connect both SMA connectors to the splitter and you're done.

You can now connect your SDR to the splitter on the back of the radio and tune it to 64.455 MHz and it will display the IF signal on the screen.  If you want to get really fancy, you can set up your SDR software of choice to control the radio too, but that will be for another day.

This mod will probably not do you any good unless you are using an external tuner.  If you are using the built in tuner, this is not needed.  There is a connector on the back of the radio that is used to control Icom's own amplifier. What we can do is trick the radio into thinking that there is an amplifier connected and it wants to tune.  This will cause the radio to output a low power tone for tuning.  I found several guides online, and they are all similar, but I wanted a nice looking solution.  

After lots of searching, I came across something called the Tuner Tamer by WB8LLN.  I sent Bob an email and let him know what radio I had.  He informed me he has some in stock so I ordered one.  Hopefully it will be here soon and I will let you know how it works.  The benefit of this particular solution vs other is that you activate it by pushing the button and when not using it, you can still use the internal tuner.