Softrock Lite II 05_Band Pass Filter

Install Band-specific Capacitors

Install the band-specific capacitors.

See band-specific chart for values

Check	Designation	Component	Marking	Category	Orientation	Notes
[____ ]	C04	band-specific
[____ ]	C03	band-specific

Wind and Install Band-specific L1

Install the band-specific coil, L1.

Band-Specific Details

See band-specific chart for values

• BOM Notation

  Wind the band-specific number of turns of #30 wire onto the band-specific toroidal core. E.G., "38T #30 on T25-2 (17")" means use 17 inches of #30 wire to wind 38 turns onto a T25-2 toroid

• Turn Counting

  Each pass through the center of the core is counted as a turn when winding the inductor.

• Coil Orientation

  L1 is mounted vertically and supported by its leads.

• Lead Preparation

  Be sure to remove the enamel coating on the wire before attempting to solder an inductor lead to its associated mounting hole. The enamel coating on the #30 wire provided in the kit does not heat strip very well but may be stripped by use of a small folded over piece of Emory paper where the lead is pulled through two facing surfaces of the Emory paper multiple times to sand off the enamel coating on the wire end.

Check	Designation	Component	Marking	Category	Orientation	Notes
[____ ]	L1-core	band-specific
[____ ]	L1	band-specific

Wind and Install band-specific T1

If T1 is not wired correctly to the six holes on the Lite circuit board it can result in very low receiver sensitivity. You should carefully read this section and study the photo below showing how to mount the transformer.

• Band-Specific Transformer Details

  See band-specific chart (or BOM, above) for values

• BOM Notation

  The winding details will be in the form: "nnT/2 x mmT bifilar #30" on Txx-x (LL")". This translates to:
  • Using a toroid Txx-x and LL inches of #30 wire, wind a primary with nn turns
  • then, using LL inches of #30 wire folded in half, wind the 2 secondaries on top of the primary for mm turns

• Primary Winding

  The primary winding is of the band-specific number of turns. Wind the primary winding with the specified number of turns of #30 AWG enameled wire so that the primary winding starts and ends at about the same point on the core and is uniformly spread around the core.

• Secondary Windings

  The secondary uses lengths of #30 wire, twisted together into a bifilar pair that has approximately 2-3 twists per inch and is wound over the primary, using the band-specific number of turns.Wind the secondary windings with the windings starting and ending just slightly clockwise around the core from where the primary winding starts and ends.

• ID and Tag the Winding Leads

  After striping and tinning each transformer lead at about 1/8 of an inch from the core, determine the two pairs of leads of each of the secondary windings by use of an ohmmeter. I like to use short lengths of insulation from hookup wire to identify two of the 3 sets of leads in these transformers.

• Transformer Orientation

  (Refer to the graphic, below): Correct wiring is with leads from one side (the "a" side) of the core going to a group of three holes and the leads from the other side (the "b" side) of the core going to the other group of three holes as shown below.
• Note the photo below shows the holes for the primary ("P") and each of the two secondary ("S") leads, with the "a" and "b" designating from which side of the core the particular winding's lead should go.
• for example:
  • The primary winding's "a" lead would go into the left-hand "P" hole
  • The primary winding's "b" lead would go into the right-hand "P" hole
  • The first secondary winding's "a" lead would go into the left-hand "S" hole in the middle row of winding holes
  • The first secondary winding's "b" lead would go into the right-hand "S" hole in the middle row of winding holes
  • and so on …
• Be careful when threading the leads through the holes to avoid their getting tangled up with nearby components!

Check	Designation	Component	Marking	Category	Orientation	Notes
[____ ]	T1-core	band-specific
[____ ]	T1	band-specific