On the ground range checks are a waste of time... You will get different results with different locations and surface types. Anyone who does a range check with the receiver antenna within 8 to 10 inches of the ground, is I'll say it again wasting his time! Keep in mind you will never fly with no transmitter antenna, right... So given your poorest range check results.... with your transmitter antenna where it's supposed to be and fully extended... your on the ground range at worst will be 700 feet. Normally that distance should be plenty of distance before you become airborne where the effective range multiplies exponentially.

So learn to do a good range check, and make corrections before flying:
1. Find your ECU unplugged (NO Turbine components functioning base line range) the receiver antenna needs to be 3 to 4 feet above the surface! This means fail-safe free operation all transmitter orientations, (360, up & down). With a well matched receiver & transmitter, assuming a JR10X system that distance should be no less than 225 feet, and more normal with good matched alignments near 300 feet.
2. My suggestion is not to fly if the ultimate range with turbine running @ full power is less than 225 feet. So if your starting with a base line of 225 feet your more than likely going to have to do some installation magic as suggested by wojtek.. You will probably have to do a little of both, installation corrections and Trans. / Rec. tweaking.

The most reliable range checks are done with the transmitter antenna fully extended, just like your going to do when flying. They are a pain in the butt to accomplish, but after doing a Real Range check you'll know for sure your ready to fly safely. Base line distances should be between 2100 & 2630 feet. The very poorest trans. ant. fully extended range check, turbine @ full power should not result in a fail-safe distance of less than 1800 feet.
Please don't assume your 940s receiver is any better than any other... shoot I've got plenty of old 910 Z types that are as good as any dual conversion. The only way to know is to check them. One of the best ways to do that is to have several same type receivers and compare them all. You will find out very quickly no two receivers are the same, no two installations give the same results. My experiences have shown me that about 50% of all rec. / trans. combinations can be tuned & aligned better than they come out of the box!
Lee H. DeMary
AMA 36099