The cable that came with my H9 Alpha trainer (JR Sport) had a Y on one end, with plugs for both JR and Futaba. I never tried it with a Futaba, but I think it would have worked with a Futaba as the buddy box. At least that's what the manual said.

I donated my free AMA buddy box to the club after I soloed, but I have an extra 4ch JR Sport TX that I pulled the crystal out of to use for training my kids.

One thing to be careful of when using a computer radio for training, is that all of the settings will not always work on the buddy box, especially dual rates and expo. You should always try to set up your trainer without using these settings.

Good luck