Here is a simple way to construct neat, sturdy tapped inductor coils for antenna matching units or VFOs.

• Choose plastic plumber pipe of desired diameter with thick wall thickness.
• Cut the pipe to desired length. Make holes for the mounting screws.
• Make a V-shaped groove along the entire length of the tube.
• Wind the coil with, say, #18 copper enamelled wire as tightly as possible. Solder the ends on tags mounted at the ends of the tube with screws, as shown.
• Take a suitable piece of wire or lassing thread or plastic sleeve of appropriate diameter and wind it in between the spacing of copper wire to ensure uniform spacing. Since the copper wire is not yet wound tightly, it will be possible to space the turns evenly along the whole length of the tube.
• Take a small screw driver with blunt edge / any rod with blunt V-shaped edge and hammer down very slowely the copper wire into the V-shaped groove leaving those turns where you would like to take out the taps. This will make the coil very tight and the windings will now hold their positions.
• Remove the wire used for spacing the turns. Remove the enamel from the tap positions and tin these points with solder.
• Coil is now ready for use!