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Doublet

The main HF aerial is a doublet with a 130 foot top and fed with 33 feet of 4” spaced ladder line open wire feeder.

Due to the size of my garden the angle between the wires is only 70 degrees, the northern leg is a straight 65 feet but the southern leg is straight for 55 feet with the last 10 feet nearly vertical to about 4 feet above ground level.

The ends of the legs are about 14 feet above ground level with the apex / feed point at 30 feet.

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A 33 foot length of ladder line under construction, I used plastic plant labels doubled up and secured to the wire with tie wraps.

The wire is 2mm2 28 strand copper wire with light grey insulation and the spacers are 15” apart.

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To aid construction I made a jig from laser cut MDF, This ensured that the holes for the tie wraps were drilled centrally to the width of the spacers and the correct distance from the ends.

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Finally some sort of termination for the feeder was needed before it went in through the wall as 300 ohm ribbon cable,

I decided to incorporate a 6mm spark gap and 100K Ohm bleed resisters from each side of the feeder to earth, more to discharge rain and wind static rather than handling a direct lightening strike, the centre terminal is connected to a pair of copper earth rods.