Dont forget though that electricity is vital ! the smaller sets dont need much, but for any long term disaster an off grid power source is vital.
PV or wind are the obvous sources, with a generator worth considering
Yes, our 100w rig does consume quite a bit of power when transmitting. Worth bearing in mind that one tends to be listening and scanning more than transmitting. In this case the equipment uses much less power. Solar or wind is a much better solution than generator. I've been involved in numerous "field days", operating from remote locations where a generator has caused a lot of interference problems.
The secret is in the antenna. TBH, our 100w rig is overkill (although a friend of mine would disagree - he's not happy with anything less than a kilowatt
). We have had great long-distance results with our little 5w portable, by making sure that we are in a good "take off" location, and through careful antenna design. And that runs on AA's if needed! Certainly a little 7Ah gel battery will keep it going for ages.
"Proper" amateur radio requires the correct licence and it is an offence to use such equipment without a licence. Who cares after the SHTF ! but I would strongly advise against breaking the law whilst times are normal.
A foundation license is quite easy to get. The course takes, typically, a weekend and is a combination of technical, procedural and legislative information. There are a couple of practical tests and a short multi-choice test at the end, and that's it. As of a couple of years ago, the license is now "for life" - you don't have to renew it each year. The technical stuff is easy - Ohm's law is about as complicated as it gets.
My best advice if anyone was interested, would be to find a local club (go to the RSGB website) and pop along for a couple of evenings. Most clubs offer foundation license training and assessment, and the members are usually very forthcoming at getting newcomers going and into the hobby. My son and I started as complete beginners. The local club organised a course for the scouts (he was a member, I was a leader), and they couldn't have been more helpful at getting us going - even lending us some equipment until we'd bought our own.
TBH, the best reason for getting licensed, apart from staying legal, is that you learn about the technology and how to make it work. Post-SHTF, it would probably be quite a useful skill. Not up there with medicine and carpentry, but useful nevertheless.
It's also quite fun, and definitely not just about being hunched over a microphone in a draughty shack. Some things us amateurs get up to...
Amateur Radio Direction Finding:
Sort of like orienteering, but using directional receivers to locate hidden transmitters
SOTA (Summits On The Air):
"Bagging" mountain tops by climbing them and then logging contacts with other radio operators, using lightweight kit.
Contests:
Making and logging as many contacts (usually long-distance) as possible within a set period (usually 24 hours). (This gets taken VERY seriously, especially by the Europeans!).
DX-Peditions:
Travelling to remote, usually inaccessible, locations, setting up camp and a base-station for a few days, and making as many contacts as you can.
All of the above involve pushing your equipment to its limits in order to get the best results, and that's where the learning happens.
"73's" as we say. ("Have a nice day")