Bought a cheap mCPX off eBay that had a broken 3-in-1.  Fixed the 3-in-1 and converted to brushless using C05XL and super-FET XP-3A (double FET’s).

Main motor PWM signal (from resistor on back of board) is 1kHz.  On the 9x using OrangeRX TX module throttle ranges from -72% (completely off) to +72% (solid full throttle signal).