Foundations Of Amateur Radio

Foundations of Amateur Radio Have you ever had your radio on, listening around, say on 40m and heard the following: "CQ, CQ 40m, this is VK6FLAB, calling CQ 40, CQ 40m, calling CQ" Apart from the fact that the station calling seems pretty desperate for a contact, you're tuned to 40m, why on earth would you actually mention that, what's the point of telling me what band you're calling on, when clearly I'm hearing you on that band? The answer to this question is in harmonics. At the heart of every radio is an oscillator, set to some or other frequency that forms the basis of all that happens around it. In order to arrive at different frequencies, we add and subtract, double and halve frequencies, all combining to arrive at the various frequencies and bands we use. I'll use some fictitious numbers here to give you an idea of what's happening. Imagine that you have a 3.5 MHz oscillator. With it you can double it to 7 MHz, double that to 14 MHz, double it again to 28 MHz, that's 80m, 40m, 20m and 10m, just