There was a good response to my video post on radio circuit modules a few days ago. So here's another. In this video I discuss calculating tuned circuit values in your head. That could be handy for various transmitter, receiver and antenna projects.
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From Dale - W6BYU
ReplyDeleteI enjoy your “daily antenna” blog, and marvel at how long you have managed to keep it going. I had enough trouble doing one article a month for a newsletter, but those were longer.
However, I’ve tried to post comments a couple times and don’t know that they have showed up, since I don’t have a Google login.
But I wanted to note a simple formula that I use for calculating coils and capacitors in my head that also gives reactance.
For a coil, the inductance for a 200 ohm reactance is given by the wavelength (in metres) divided by 10.
For a capacitor, the capacitance for a 200 ohm reactance is given by the wavelength (in metres) times 3.
So for 80m, it would be 8 uH and 240 pF.
I can then scale from there as needed.
No, it isn’t exact, but close enough to give a good starting point, especially with hand-wound coils that won’t be precise anyway. It’s actually quite easy to work out problems while driving the car or mowing the lawn, and a 200 ohm reactance is a reasonable value for many tuned circuits.
Keep up the good work!