There's also a workaround related to a specific power up/down/up sequence you can do ... forgot the details.
I am using Futaba 8U with Hitec synth tx module.
When I switch on the tx, it sometimes occurs that tx warns me by an abnormal
sound indicating "speed brake".
It can be solved when I cycle the power sw off then on.
Is what you say this?
The receiver I use is a non-synth Futaba, and I never have a problem with the tx
to fly so far.
Tsutomu Mabuchi