Look at it this way, the radio world for our uses is split into two sections 1: Above 30Mhz (Vhf/Uhf) Police, Fire, Aircraft,etc.) Range Approx. 50 Miles.) 2: Below 30Mhz (HF) This is the Shortwave Band.
It is for the most part all AM mode, and is devided into AM (Broadcast Stations: Radio Canada, BBC,
Voice of America, Radio China, etc) USB Upper Side Band ( Military Air, Marine, Airline Long Distance
Operational Control, Amateur Radio Operators, etc) Range World Wide.) LSB Lower Side Band ( Same
as USB.)
Below 30Mhz the most important part of your system is the antenna.
There are some top of the line recievers that will recieve both, but while you are searching the HF band the local Fire Companies may have a working fire and you missed it. Two radios is the way to go. Twenty radios are better, but get started with Two for now.
Remember one very important thing, The only reason to get up and go to work every day is so we can buy more radios.
Good Luck
73s