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 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
