I wired my first QMX for 9V, and have been very happy that I did.
I also use a PD power bank and 9V trigger cable for it, and it has worked very well.? The powerbank measures right at 9.0V, but at transmit there is about a .2V drop in the cable, so I am always transmitting at about 8.8V, which is a fine safety margin, even for FT8.? Note that because of the steeper voltage curve for a 9V build, you don't need to reduce the voltage as much for the same margin.
And the power bank I chose is an Anker 10000mAh unit that is smaller than the QMX - a perfect match, which gives me several hours of operation.
Stan KC7XE
