To what extend do I need to worry about nearby power lines causing interference
Actually, we have had very few problems associated with power lines
or transmission towers. In general, it is the other
sources of EMI/RFI that are of most concern, such as CRT computer monitors
that are in the VLF range. Most of these devices have a horizontal sweep
of 24.8 KHz and NLK, one of our transmitter stations, transmits on... 24.8 KHz.
Our initial testing was done at a school with power lines (transmission
towers), and we never saw any trouble from them. However the computer lab
in the classroom next door did. The solution, we found, was to move the
antenna about 10 feet (3 meters) or more from the troubling source(s) and
the SID monitor will work fine -- if the source is more intense then further
away is better... It doesn't have to be outside or on a roof, but these
seem to work best as they will not be disturbed.