First of all, get yourself a good digital voltmeter/multimeter. As a serious kit builder, you will use it a lot.
Most of the wall AC/DC power adapters are notoriously mislabeled. If you want to use one for your project, measure its voltage under no load and full load. Make sure it is not higher than 12 Volt. Many of them do not have a good voltage regulator built in. Don't use the QDX as the test load. I use a combination of power resistors. Under full load, also measure the AC component. It should be less than about 50 millivolts.
About power measurement: Most commercially available (low-cost) power meters are not accurate enough to be used to optimize the output power of a multiband QRP transmitter. If the power meter is built for measuring high power as well, then they may be 50% or more off on QRP power levels. They are not calibrated for all the bands we are interested in. Over the years, I found a simple method to measure RF power with reasonable accuracy and low cost. I use the dummy load of QRP-Labs with its peak voltage sensor output. Under load, I measure the DC voltage of this sensor output. I add 0.5 Volt for the diode loss then I multiply the result by itself (square it). I divide the result by 100, and you will get the accurate value of the power injected into the dummy load in Watts. It works equally well for all shortwave bands.?
