Use this site to render the horizon panorama from any place on earth. –

Create an account and create antenna coverage plots here:

Very good explanation of the sun and HF radio propagation:

Coax loss calculator:

Great site w many topics covered- baluns, antennas, etc:

Mag loop antenna info and links:

Another good mag loop info source:

Ferrite vs air choke data (mixes and coax types are silly but principle is point):

Faraday cage info:


Site w real time APRS info heard from the ISS (use it to see if you make it in etc!):


Misc and random- 

Motorola Micor squelch explained: