[Elecraft] Atmospheric Noise

[Ron D'Eau Claire]

Something else to consider is that the offending noise may not be
atmospherics at all. Newer 'wall wart' power modules used on many
electronics to drop the mains voltage to what the unit needs are often
switching power supplies. I have at least one that generates a broad-band
hash that has no specific frequency but which simply blankets he HF spectrum
from 160 up through at least 20 meters with what sounds exactly like typical
QRN. 

I wouldn't have suspected it wasn't "atmospheric" except that my noise level
is frequently very low on 40 and 80 - often about S2 - and suddenly it
seemed that every evening I listened it was about S7! Finally the light
dawned and I pulled the plug on the new gadget installed clear across the
house and the S-meter fell back to S2. 

As Don noted (and several others including Edwin have confirmed with their
suggestions) the *only* way to reduce the level of broad-band noise is to
reduce the bandwidth. All the suggestions made are various ways to reduce
the ultimate bandwidth heard. 

For me, it's a big tradeoff. I like a wide bandwidth because my brain much
more comfortably recognizes the tone of the signal in wide-band noise than
when the noise is focused on the same frequency as the signal as happens
when the bandwidth is narrow. In every case, there's a bandwidth setting
that provides the optimum between compressing the noise into one frequency
entering my ears and having the bandwidth too wide so that the sheer total
noise power is disturbing. 

But the bottom line is that there's nothing like a "quiet band". Be sure
that "band noise" is really not something you can shut off! 

Ron AC7AC