To reiterate, and relate my experiences. You must have a computer radio to buddy box the DX6i, the manual states this.

I tried a JR Quatro and had no luck. So I hooked up my JR 6102 and it works flawlessly.

I am told, though I cant be sure, that the DX7 does not have this limitation so I assume this is a case of we got what we paid for..