American Radio Relay League (ARRL) including DXCC: http://www.arrl.org/home
British Amateur Radio Teledata Group (BARTG): http://bartg.org.uk/wp/
British Amateur Television Club (BATC): https://batc.org.uk/
British QRP Club (GQRP): http://www.gqrp.com/
British Railways Amateur Radio Society: http://www.brars.info/
British Young Ladies Amateur Radio Association: http://bylara.org.uk/
Coax Calculator: https://www.qsl.net/co8tw/Coax_Calculator.htm
CQ Magazine: http://www.cq-amateur-radio.com/
International Amateur Radio Union (IARU): http://www.iaru.org/
International Lighthouse Lightship Weekend: https://illw.net/
International Short Wave League (ISWL): http://www.iswl.org.uk/
International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html
Jamboree On The Air (JOTA): https://www.jotajoti.info/
Mills On The Air (MOTA): http://www.mills-on-the-air.net/index.php
Northern California DX Club (NCDXC): http://www.ncdxc.org/
Ofcom: https://www.ofcom.org.uk/
Practical Wireless: https://www.radioenthusiast.co.uk/
Radio Amateur Old Timers’ Association: http://www.raota.org/
Radio Museum: https://www.radiomuseum.org/
Radio Society of Great Britain (RSGB): https://rsgb.org/
Radio User: https://www.radioenthusiast.co.uk/
RAIBC (supports radio amateurs & SWLs with disabilities): http://raibc.org.uk/
Royal Air Force Amateur Radio Society (RAFARS): https://www.rafars.org/
Royal Navy Amateur Radio Society: http://www.rnars.org.uk/
Royal Signals Amateur radio Society: https://rsars.org.uk/
Sisterhood Of Amateur Radio: http://www.soar-yls.com/
Spaceweather.com: http://spaceweather.com/
Spot the International Space Station: https://spotthestation.nasa.gov/sightings/
Summits On The Air (SOTA): https://www.sota.org.uk/
UK Microwave Group: http://www.microwavers.org/
Vintage & Military Amateur Radio Society (VMARS): http://www.vmars.org.uk/
WhatsMyLocator: https://www.whatsmylocator.co.uk/
Worked All Britain (WAB): http://wab.intermip.net/default.php
Yasme Foundation: http://www.yasme.org/