That's a cool test..........

Part two of the test i was told the sats are self heating so 1 hr at -20 no power then connect battery.

Hey buddy.

Have you actually popped the 3GX in the freezer to?
While i never had this problem with my 3GX's, I have seen this quirk at the field. On power up the 3GX puts the servos hard over. Disconnecting and reconnecting the power see's the unit power up normally.
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Hi Ian, its not my 3gx I am waiting for him to come back to me on how He is testing them but he has two DSMX that dim and flash when they get cold ? Started with what seems like mini lock outs when he was flying on a cold day.

What does a flashing sat mean? Lost power and re-gained it with the same channels selected on the bind i.e. brown out? I think...
Maybe look for loss of voltage to RX or sats at low temperatures - the electronics should be good to minus 5 or 10.
Possibly poor electrical connections as crimp contacts lose their springiness, or low volts supply?
My thumbs wouldn't work at plus 4 in the wind today...

Hi All,
It was my 450 3GX which kicked off this trail of investigation with Jason. Basically, the model performs faultlessly in warm weather but when the temperature drops to around three degrees, weird things happen. The symptoms were intermittent binding of one or both DSMX sats (taking ages to bind) and when they did bind the LEDs would flicker (not flash) like there was a loose connection or the BEC was dropping out. Intermittently it would seem to go into lockout in the hover, for a fraction of a second, with the model suddenly dropping by a foot and then recovering. I assumed it was the 3GX, with early units suffering problems when cold. Armed with an oscilloscope and freezer spray I systematically started to freeze and check individual components. I started with the ESC looking for cold start problems with the BEC....nothing. Next I froze hell out of the 3GX....nothing. I then cooled each DSMX sat in turn....bingo, with very little cooling the fault was immediately repeatable. I swapped the sats for two DSM2 ones from my Goblin and bingo, no matter how much I cool the sats or the model, everything appears to be tickerty boo with instant rock solid binding. Next I need to check for variation in data rate from the DSMX sats when cold. I reckon the rate changes and falls outside the capture range of the main receiver/3GX. From what I can gather spektrum changed the satellite communication protocol significantly when designing DSMX effectively removing a redundant message frame (probably used for error detection and correction in DSM2) and adding additional information to this frame to allow support of up to 18 channels instead.