Re: Should I lower QCX power when using to send WSPR? If yes, how?
QRP Kits / Pacific antenna makes a stepped attenuator kit that sells for $25 and it will easily handle 5 watts in.
I would reduce the supply voltage to the QDX to lower the output to about 2.5 watts (or less) to keep the PA running cool and then use one of these attenuators at the output.
I would think that 41 dB in steps should be sufficient for your needs and it would easily allow you to vary the output according to your needs.
P.S. There is a graph in the QDX manual with two curves (for 3:3 and 3:2 ratios on L1) showing the RF power out vs supply voltage.