More radios
Going back to the amateur radio thing, I have a Trio TS-520 (pic at the top of www.k4eaa.com/types.html). It's a little tricky to set up and tune (you need to be able to read a vernier scale to tell the frequency, and before you transmit there are three separate adjustments that you need to make). All the electronic bits are easy to get, even the three valves that form the 100W power amplifier (the bit that needs the three adjustments). The thing is, it is *measurably* more sensitive and has clearer audio than modern radios costing literally 100 times as much as I paid for it. Also, because of that valve amplifier and its three adjustments, you can pretty much connect up anything approximately correct as an antenna and it will work. Try that with a transistor amplifier and very expensive smoke will come out.

I've always been interested in space, and used to sit and watch satellites go overhead. You can see the ISS go by if it passes just before sunrise or just after sunset - go to www.heavens-above.com and stick in your location to find out when. Even if you can't see it, though, you can sometimes talk to the guys aboard on the 2m (144MHz) band. When they're not about, they run a packet radio "digipeater" which listens to a burst of digital data you send, and retransmits it. Since they're 250 miles up, this covers a huge part of the world at any one time. You can hear it with an ordinary handheld scanner - sometimes even when you're inside, if they're right overhead.

Length? 468 divided by the frequency in MHz will give you it in feet.
(gordonjcp, Sun 7 Nov 2010, 11:06, Reply)