On Fri, Mar 16, 2018 at 1:32 PM, jrusgrove at comcast.net < jrusgrove at comcast.net> wrote: > VLF enthusiasts > > Anyone have an overnight spectrogram from last night including the 18 kHz > frequency range? https://www.dropbox.com/sh/2vl4l049763m863/AAC63yTp04SSMoI3t6lSKoqna?dl=0