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Thursday, September 02, 2010

The Variable Capacitor & Magnetic Loop Antenna Project - update 2 Sept 2010







After some tinkering.... I decided to use a single cable for both RF and DC... I planned to make use of the FT897D ability to tune the antenna instead of having a separate box just to tune the variable capacitor. Since the FT897D has a built-in circuit to control the YAESU ATAS screwdriver antenna, it should be able to do the same on this project.

I took some gears from an old CD player and a motor, coupled it with the motor controller that I made sometime ago for the Screwdriver Antenna project. I still need to make the Bias-T circuit before I can test the motorized capacitor. So far, with manual tuning, I can tune to 10m & 20m. I decided to abandon the wide-band loop project as I realized it require a much larger capacitance. It is very tricky to get a high maximum capacitance while having a lower minimum capacitance...

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