I recommend this also. While RT Systems does sell a version made for the 8600, I've had it trash my memories more than once. I found I can use RT's software as long as I only work with small groups of frequencies That seems to work most of the time. RT's software allows copy and paste operations above what Icom's CS-R8600 software allows. But Icom's software is much faster in all aspects over RT's software.Welcome to the R8600 club. I've had mine for a year and I feel I have not even scratched the surface of this beast. Get the ICOM programming software, pricey but worth it.
Some users use an external spreadsheet program like Excel that can be made to work well with importing things into the R8600's memory channels. RT's software does not allow changing several of the settings unique to the radio. Icom's version work perfectly and allows you to adjust about every possible radio setting via software.
Of course you can always get the software at a later date. That will give you some time to research the pros and cons of each software.
I ended up with both software programs for working with the 8600 memories. Each one has benefits over the other.
In addition to the Icom receivers forum here, there's a pretty active groups.io group for the 8600 also. It's definitely worth joining the Icom receiver related groups.io groups
I don't do Facebook but I've seen mention of some pretty active Icom Facebook groups as well. If you are into Facebook, the related groups would probably be worth joining.
Do you have a power supply?
The 8600 does not come with a power supply. They sell a matching speaker for big bucks that has an 8600 compatible power supply built in.
You really only need a well regulated 12 VDC supply capable of maybe 5 amps or more. That will give you a little breathing room as you are not running the supply near its current limit,
You should be able to find a decent linear 12 VDC supply for a decent price. I'd stay away from Switching type supplies. They are getting much better these days but many of them still emit RFI into the receiver.
Some users checked the Icom supply built into the matching speaker and found that it was not a regulated supply so it put out near 18 VDC with a small load. This higher voltage was making the users 8600's run much warmer than normal. Something to watch for as heat kills electronics.