Can't figure out the MOX feature in my new FT-891. Supposed to give carrier output, i.e. for adjusting an external tuner when working SSB. In the '891, the process appears to be: F key > Function 2 > MOX > press the MULTI knob. When I do that, I get a few more amps on the d.c. power supply and the red transmit light comes on, but zero RF output, in any mode. Only way to tune the antenna is set CW mode, use a straight key, and go key down. No help so far in the Yaesu Op manual, Advance manual, Google, etc. What's the secret?