Yes, I added an on/off switch. I have the German enclosure. I added the switch just above the earphone jack. Seems like a good place.
I drilled the enclosure with the right size drill. The enclosure is aluminum so it was an easy drill. Bolted on the switch. Connected the switch in the RED (positive) wire. When it's off, it's completely off.
BTW, I now needed to re-align my unit. In the NAQCC sprint last night, I was disapointed. Turns out that the sensitivity was way down, and I could hear stations on my big rig that were silent on my QCX. So this morning I went through the alignment process again. Don't know why, but aligning R27 (I/Q) helped in aligning C1 for peak. R24 and R17 (audio phase adjust) seems to like it best when I crank them down all the way - clockwise. Is this expected?