What use is an F-call? I love it when I get feedback about things I talk about. It helps me understand when I know what's going on and when I'm being a doofus. Recently I was talking about building an antenna in preparation for a contest. It was intended for 80m, but turned out to be perfectly resonant on 160m. Not what I had intended. And to add insult to injury, I broke one of the segments of my squid-pole. In the telling of my tale of woe, I received an interesting comment from a fellow amateur who has been around the block a few times. He pointed out that we work with harmonics all the time, 160m, 80m, 40m, 20m, 10m and so on. Wavelength halves, antenna size halves. Proportionally all of it is related. There is no need for me to build an 80m antenna with 80 meters of wire hanging off a 12m squid-pole to test my design, I can make a 2m version with 2m of wire and a 30cm centre pole. Something I could conceivably hold in my hand, rather than fill-up a back-yard, spend ages stringing up, attempting to trim and re-arrange. In hindsight, the comment was so obvious that all I could think was duh. Of course if it really was that obvious, I'd have thunk it up all by myself. Instead, I relied on feedback from another amateur to point me in the right direction. Next step is to set one up, and measure what is really going on. I can use a hand-held radio to transmit and even go about plotting the actual signal strength by measuring around it. A fine project for a rainy day, or a field-day. So, if you have a thought that might help out another amateur, don't be shy, share your insight. Who knows, both of you might learn something from the experience. The name of the amateur, Richard, VK6BMW - thanks! I'm Onno, VK6FLAB.