Magnetic Loop – Capacitor Box

After building several tuners it was time to build a magnetic loop that I could set up outside in my garden.
I built a magnetic loop for the 80m band to the 30m band.
The magnetic loop has a circumference of 6 meters and a diameter of 1.9 meters. The material I used is 2.2cm copper tubes used in sanitary installations.
Visit the website to calculate your magnetic loop.

To get the loop into resonance on the frequency we want to use it, we need to add a capacitor. For this antenna, I chose an air variable capacitor. The capacitor was made by HA8DU and bought via a Dutch reseller.

Magnetic Loop Air Variable Capacitor

The capacitor is controlled by a Nema 17 stepper motor., which on his turn is connected to the automatic magnetic loop tuner.

Magnetic Loop Air Variable Capacitor

On the capacitor, I’m using a 60 teeth GT2 pulley, and on the stepper motor a 16 teeth GT2 pulley. The belt is a GT2 280mm rubber band, reinforced with fibreglass. Do not use a belt with steel wires.

Magnetic Loop Air Variable Capacitor

To connect the capacitor to the loop I used soft copper bands and fastened them with hose clamps.

Magnetic Loop Air Variable Capacitor Magnetic Loop Air Variable Capacitor

If I would have to make this loop antenna again, I would switch the positions of the tube clamps and the hose clamps. Also, would I turn the capacitor 90°. But now, for the moment, this is fine 😉

Magnetic Loop Air Variable Capacitor

All closed up. Next step is to tape the box with Duct Tape and make sure all other holes are sealed with silicone. Then I’ll paint the loop black and search for a better way to attach the coupling loop.

AliExpress parts list:

Nema 17 stepper motor bracket:

Nema 17 stepper motor 45 Nm, 1.5A:

GT2 Pulley 16 teeth:

GT2 Pulley 60 teeth:

GT2 Rubber Belt:

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