I originally bought a Mini6 for my Nexstar trainier and brought it out to the field and noticed that I was getting a lot of hits on it. I tried it several times (ch29 and a 6EXAP Tx) and still had this problem. Tried a friend's Supreme IIS and didn't have a single hit. Took the Mini6 back and exchanged it for the SupremeIIS and have not had a problem. If I use a nitro plane, I will stick with a dual conversion. Check out Ebay, there is a vendor selling new SupremeIIs for about $40 with the crystal and $3 shipping. I would go that route.
Best of luck,
Curtis