For BPSK31, the most common flavor of PSK31, the sideband does not matter. As long as you can see the station in the waterfall display, you can work it.

With QPSK31, however, the sideband does matter. You can choose either upper or lower sideband, just make sure that both stations are on the same sideband. Most QPSK31 activity is on the upper sideband.

Some operators think that a higher reading on the watt meter means a better signal. However, that is not the case. Rather, a clean signal is to be desired. One easy way to check the quality of your signal is to look at the automatic gain control meter on your radio. For the optimum signal, it should read near zero. Better yet, have the receiving station check you IMD (most software programs have this feature). For the most accurate measurement, you can purchase a IMD meter.

This being the case, a 35W signal with an IMD of -30dB is better than a 100W signal with a -19dB IMD. This shows that it is important to tune your transmitter for maximum quality, not maximum power.

To improve your IMD, try adjusting volume levels on the computer sound panel, sound card interface volume, as well as transmitter settings.

Check their website for info and pictures: http://www.amqrp.org/kits/nue-psk31/index.html