Arghhh! Last night, on the workbench, I plugged in four different batteries in succession and the tx and rx bound instantly each time. Taxied around the rec room floor and all looked good.
This morning at the field the first battery bound instantly and I got in a nice fifteen minute flight (timed).
The second battery, when connected, took about 5 to 10 seconds to bind, but did bind, but then after a few minutes of calm flying the plane became unbound! The motor turned off and the controls surfaces went to neutral. The plane settled into a slow shallow decent, unfortunately into a fence. Damage repairable, but man that's frustrating.
TX batteries were fresh
TX antenna was straight.
Tx power did not go dead during lost contact (light stayed on).
When I disconnected and reconnected that same flight battery the plane bound and appeared to be ready to go again (plane was too damaged to fly, at least prudently)
I flew my t-28 um afterward (same tx) for a half hour with no binding problems at all.
It's not a range issue. As you will find in any Spektrum Tx manual the signal is weak of the end of the antenna. If it is pointed at the plane it can contribute to loss of control. I have experienced this myself with an AR500 Rx and DX5e. 200 feet away and antenna pointing right at the plane. Lost all control. Looked down at my Tx and saw the antenna pointing right at the plane, which I don't normally do. Flipped it up and regained control. This is the only time I have lost control with this combination.
Holy crap! I left a message with HH tech support and they called back within ten minutes. The guy listened to the problem (very sorry to hear about my crash) and announced he's sending a new rx in the mail. I guess I've become so accustomed to lousy customer service I've come to expect it from everybody. What a nice change!