HFU HF Underground
Technical Topics => Equipment => Topic started by: smith on January 20, 2020, 0214 UTC
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Im thinking about setting up a beacon below 3 MHz, Id like to use a loaded vertical of some sort, how do I go about tuning it without a variable capacitor using just an inductor if possible, can anyone make some suggestions.
Does anyone know anything about the antennas used in the 2 mhz hifer beacons?
Thanks
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You are asking to tune the inductor instead of a capacitor. One way to do this inexpensively is to use what is called a "wandering lead". See the yellow wire with the alligator clip on the end of it in the photo I have linked to. Essentially you will tune the inductance by choosing the tap point on the inductor.
https://www.mfjenterprises.com/Downloads/MFJ-65/MFJ-65.jpg (https://www.mfjenterprises.com/Downloads/MFJ-65/MFJ-65.jpg)
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You'll need to tune out the 'reactance' so you will need a capacitor.
It's simple and called an 'L' match, real name is Conjugate Match.
Buy one of those cheapo VNAs to measure the properties of your antenna.
Oh, you'll need a Really good earth, lots of radials!
Str.