MFJ Enterprises:   MFJ and Affiliates Retail stores                    Impedance Matching Design Tool
  HRO:  Ham Radio Outlet Store                                           Distance and Bearing Calculator
  EZNEC: W7EL Antenna Modelling Software                                 Magnetic Loop Design  (Open File as Excel App)
  DX Engineering:  Ham Radio Equipment and Supplies                      LOTW ARRL Logbook of the World
  ICOM America:  Amateur Radio Transceivers and Accessories              DX Watch  DX Cluster 
  KENWOOD Radio: Amateur Radios and Accessories                          Toroid Specifications  Toroid core reference
  YEASU Radios: Amateur Radios and Accessories                           DX Expeditions  Club Log DX Listings
  QTH.com: Ham Radio Classifieds                                         FCC Home Page  FCC Cores Login
  QRZ.com: Ham Radio Callsign Database                                   RF Exposure Applet JS RF Exposure Calculator
  Alpha Delta.com: Antennas and related products                         LB Cebik Radio Page  W4RNL Antenna Compendium
  GigaParts:  Ham Radio retail store                                     Homebrew Projects:Collection of Homebrew Circuits