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These instructions are for placing the maximum inductance at lug L on SW2
( ) Before beginning, refer to W5USJ Chuck Carpenter's excellent coil graphic Click Here to View.
click here to see the #1 lug position location for reference.
( ) Remove and clamp the shaft of the switch in a vice
( ) Solder one end of a 2" wire to the center lug . The opposite end of this wire will go to the 10 o'clock pad later.
click here to see the 7 & 10 o'clock pad locations for reference.
( ) One end of the buss wire will be soldered to pad 7 (Gnd) on the pcb during final assembly.
( ) Slide the T106-2 toroid down the bus wire until it rests centered on the switch lugs with the red side up.
( ) The first 3 turns are 1 turn per lug.
( ) Leave about a 3" pigtail.
( ) Begin the winding sequence by threading the long end of the buss wire up, out, around, and down through lug #7. This will begin the grounded end of the coil, 1 tap up from ground. Refer to the schematic.
( ) Continue the winding sequence by bringing the wire UP through the center of the core, around the outside of the core and through lug #6 Be sure to get the first winding started correctly by referring to this picture.
( ) The remaining single turns are made in the same manner, ending the single turns at lug #5.
( ) The turns then continue CCW, but with 2 turns per lug rather than one, finally reaching lug #10 where the coil is terminated, and soldered. Lug #10 is left floating.
( ) Ensure that the correct number of windings are placed between each lug as you wind. After passing through a lug, go around the core twice, and then through the next lug, then around twice again and through the next lug, and so on.
( ) Verify that there are 21 total turns by counting them around the inside of the core.
( ) The lug/wire joints are soldered after all the windings are completed.
refer to this picture.
( ) When finished winding the coil, ensure that the switch contact has selected the highest inductance postion i.e. the #10 lug.
( ) During final assembly place the knob pointer at position L and tighten the set screw.
Continuity Testing Your Coil:
( ) Attach one ohmmeter lead to the center lug wire with a small jumper.
( ) Then probe each lug by placing the tip below the solder joint, forcing the checking current through the solder joint.
Probe placed correctly on a lug.
( ) All lugs should show 0.00 ohms. If one doesn't, touch it up with a hot iron and a bit of solder and recheck.
( ) Remove the sub-assembly from the vise and set it aside until later, it will be installed last.
Congratulations! Your inductor/switch sub-assembly is now complete.
Click here to continue.