Self Supported

`4-Square for 80 / 75 M- Loading Coil`

Design by Eric Smitt K9ES

A 3 inch PVC Schedule 80 straight coupler has a 4 inch outer diameter. Use this to wind the coil, made from ¼ inch soft copper tubing (used for hooking up the ice maker in refrigerators and readily available in 25 length rolls at Home Depot or Lowes), winding 8 turns, leaving a 1 ½ inch end beyond the coil at both ends of the coil. This end will be soldered to the brass strip which will then wrap around the fiberglass to attach the coil in place. The brass strip is readily available at hobby stores, and is light enough to cut with tin snips, yet strong enough to support the copper ends of the coil.

The brass is soldered to the copper tubing at the ends, and then wrapped around the fiberglass. A pair of holes is drilled into the braqss (3/16 " drill), and a stainless steel screw (8-32 x 2 inches) is then placed through the 2 holes, with a self locking nut securing the screw. The screw is tightened to secure the brass and copper tubing coil to the fiberflass, without overstressing the fiberglass. The 3 wires from below and above is stuck into the open ends of the copper tubing and soldered. This coil can be compressed or stretched to change inductance as required for initial tuning. The goal inductance should be slightly below 5 microhenries..

The coil is mounted 17 feet above the bottom of the fiberglass where the fiberglass is around 1 inch diameter. Placing the coil any higher could be done, but the antenna will flex more in the wind.

Another closeup of the coil showing the wires soldered, and then wrapped on the fiberglass....

*Basic Information*	*The Pivot Support*	*DX-Spyder Fiberglass & Vertical*
*Loading Coil*	*Tuning Stub*	*Radial Ring*
*Phasing Lines*	*Tuning*	*Comtek Controller*

Pulley System

Performance

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