DC to Daylight

What use is an F-call? From DC to Daylight is a term that until I became an Amateur, I'd never heard of and since becoming licensed I've bumped into it more than a couple of times. Once you sit and think about it, the notion, from DC to Daylight makes perfect sense, but what does it mean? I'll start off with that I'm not talking about Cheap Therapy for your Inner Problem Child - the Rock band based in San Jose, California. So, DC, or Direct Current, as opposed to AC, or Alternating Current does not change frequency, that is, the positive and negative poles never swap over, so the frequency that they switch at is 0Hz or zero times per second. If you reverse the poles, the frequency at which you do that, say flick a switch once every second, the frequency is 1Hz. AC does it 50 or 60 times per second, or 50 or 60 Hz. As you keep increasing the frequency, you'll come past 160m, just below 2MHz, 80m around 7MHz, etc, onto 2m around 145MHz, 70cm and up to WiFi at 2.4GHz, then 5.8GHz, eventually, you'll get to a frequency of around 400 THz, where you'll bump into visible light where the wavelength is 750nm. So, DC is 0Hz, Daylight is 400 THz, so from DC to Daylight means from 0 Hz to 400 THz. Said in another way, DC to Daylight means "all frequencies". Of course, you could point out that there are frequencies above daylight, indeed there are. It's really a short hand term and as amateur radio terms go, it's one of the more explanatory ones. Now all you need is a DC to Daylight radio, and you'll be able to listen to everything that goes on anywhere - provided you have an appropriately tuned antenna - Hi Hi. I'm sure there are terms you've come across that make no sense. Have a look around, or better still, contact another Amateur and work it out together. The only silly question is the one you didn't ask. I'm Onno VK6FLAB