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These instructions are for placing the maximum inductance at lug A on SW2
( ) Before beginning, refer to W5USJ Chuck Carpenter's excellent coil graphic Click Here to View.
( ) Trial fit the switch onto the pc board and mark the 1 and 4 lug positions on the wafer for future reference. Starting the winding at lug 4 allows the knob's set screw to sit in the shaft slot when the pointer is on A - very solid feel and the knob won't loosen.
click here to see the 1 and 4 lug position locations.
( ) Then remove and clamp the shaft of the switch in a vice.
and 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.
( ) Pass the buss wire through lug 4 from the inside out, solder it to lug 4 and trim off any excess. like this. Note: lug 4 is the open (top) end of the coil as shown on the schematic.
( ) Then thread the T106-2 core down the wire so that it rests on the switch with the red side up.
( ) Begin the winding sequence by bringing the wire down around the outside of the core, then back underneath, up and around the core, and then thru lug 3, and back UP through the center of the core. Be sure to get this first winding started correctly by
referring to this picture.
There should be two windings on the core at this point.
( ) The remaining turns are made by threading the wire through the lugs and
UP thru the center of the core (as in sewing), and working your way CCW around the core .
Ensure that the correct number of windings are placed between and through each lug. As you wind, the first winding will begin at pos 4, go around the core twice, and then through lug 3, then around the twice again and through lug 2 and so on. For the first 9 lugs (#4 through #6 counting CCW) there will be 2 turns between the lugs. The remaining 3 lugs wil have one turn between the lugs - making a total of 21 turns with the single turns nearest the ground end of the coil.
Before soldering, double check your work by counting the number of turns around the INSIDE of the core.
Refer to the schematic. The lug joints are soldered after all the windings are completed. refer to this picture. of the first few turns and lugs
( ) Leave a 3" pigtail from the bottom of the core. The end of the winding will terminate at the 5 oclock position, and is soldered to the 7 oclock pad, which is ground. Refer to this picture to ensure that you have it correct.
( ) When finished with the winding, rotate the shaft so the switch contact has selected the highest inductance postion i.e.the 4 o'clock lug. The knob's set screw will then center in the shaft's slot, making a firm switching feel, and the pointer will be on position A. The last winding, after passing thru Lug 5, will be soldered to the 7 o'clock pad. during final assembly.
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.