Range test
You should be getting that kind of range with the antenna removed on a 10x.
I lost a Kangaroo when it went into failsafe on final because I range tested with the antenna installed but collapsed all the way. I think the best I got was about 200', but flew it anyway. That was with a JetCat V2.0 ECU. I was able to improve the range considerably with a Revolution whip antenna and a new RX (JR945). Then when I upgraded to V4.0 ECU it got even better.