Long ago I built several VLF (audio freq) receivers with various active and passive filters. The better ones were too big to take into the field and the better ones didn't perform well. Some number of years ago I got one of Steve McGreevy's little WR-3 series receivers (see http://www.auroralchorus.com/wr3gde.htm) and it was considerably better/handier than anything I'd built. The analog filtering is good enough to drop hum to pretty low levels when in the country a half mile or more away from power lines but it's still pretty bad when lines are closer.
A few years ago DL4YHF added a very nice hum filter to Spectrum Lab and it works very well. I can actually place the receiver a hundred or so ft from the house (I'm sort of in the sticks anyway) and get good results receiving the various tweeks, whistlers and other things that comprise sferics. McGreevy's site contains a lot of recordings that he's made in remote areas. Also check out Renato Romero's site at http://www.vlf.it/. His book, Radio Nature is quite good and is now avail in English translation through the ARRL. Steve, KB1TCE --- In digitalradio@yahoogroups.com, "Rudy Benner" <ben...@...> wrote: > > I would be interested to hear your comments about the Natural Radio stuff. > > ve3bdr > > > From: pseudospark > Sent: Friday, July 23, 2010 8:48 AM > To: digitalradio@yahoogroups.com > Subject: [digitalradio] Re: Cool Spectrum Analyser > > > > I've been using Spectrum Lab for years for the reception of "natural radio" > VLF sferics in the 100 Hz to 20 kHz range. It has very effective 50 or 60 Hz > filtering which permits the receiver to be used surprisingly close to > residential power lines. > > Steve, KB1TCE > > --- In digitalradio@yahoogroups.com, "Rudy Benner" <benner@> wrote: > > > > http://www.qsl.net/dl4yhf/spectra1.html > > > > should keep you out of trouble for hours and hours, let the grass grow. > > > > ve3bdr > > > > > > > > > -------------------------------------------------------------------------------- > > > > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 9.0.851 / Virus Database: 271.1.1/3025 - Release Date: 07/24/10 > 02:36:00 >
