What Use Is An F-call?

What use is an F-call? As I've said many times before, Amateur Radio blows me away. Every week I see new and imaginative things that this community achieves through trial and error, from contacts across new bands, coordination of new activities such as fox-hunts and SOTA activations. We are a fool hardy lot, climbing up hills to "activate" them, or doing the same thing for light-houses, or museums. There's a surfing contest where you collect callsigns to spell the locations of surfing beaches as outlined in the Beach Boy's "Surfin USA" song, which includes an Australian beach as well. It's wonderful to hear about Amateurs talking to other Amateurs, both using portable gear, both standing on top of a summit and exchanging reports across the country. Recently an F-call decided that he wanted to try to build a cavity from bits purchased at a hardware store. Complete with video of the achievement, testing and SWR measurements, a $15 experiment to see if he could do it. Wanting to learn mor