VLF

The latest version of the Gyrator series of VLF receivers (first developed in the 1990s) is the Gyrator III, a revision of Arthur Stokes' Gyrator II by Guglielmo Di Filippo (observer A-93).

Circuit diagrams and wiring for the Gyrator III are available here in Microsoft Word and PDF formats: .doc, .pdf

Active Observers (Data submitted within the last year)

When the ultraviolet rays from the Sun hit the Earths atmosphere the energy they possess work to knock electrons off of the atoms and molecules that the atmosphere is made up of. These free electrons make up a region of the atmosphere known as the Ionosphere. The region is strongest on the daytime side of the earth since it is dependant on the energy from the solar ultra violet rays.

VERY LOW FREQUENCY (VLF) RADIO STATIONS
                                     
           Station            Station     Frequency        Radiated
             Site               ID          (kHz)            Power
                                                             (kW)
  U.S. Navy                     
       Cutler, ME                NAA          24.0            1000
       Jim Creek, WA             NLK          24.8             250
       Lualualei, HI             NPM          21.4             566
       LaMoure, ND               NML          25.2             500

SID Monitoring Overview
AAVSO SID Program

Rodney Howe, Solar Section chair & SID leader

So, what are we looking for? Here are a couple references of SID events and their influence on the ionosphere: