Band 4: 16-30 MHz Introduction

General

See the detailed techniques for winding toroidial coils

Theory of Operation

This stage builds and installs the filter "chain" for Band 4. Refer to Jan G0BBL's Design Plots to see the performance characteristics of this chain.

1 turn Remember, when winding toroidal inductors, a single pass through the core counts as 1 turn. You might want to review Leonard KC0WOX's excellent 10-minute video on winding toroidal coils.

(go directly to build notes)

Band 4: 16-30 MHz Schematic

(Resistor testpoints (hairpin, top, or left-hand lead), as physically installed on the board, are marked in the schematic with red dots)

(Click for Full Schematic)
Band 4: 16-30 MHzschematic (go directly to build notes)

Band 4: 16-30 MHz Bill of Materials

Stage Bill of Materials

(resistor images and color codes courtesy of WIlfried, DL5SWB's R-Color Code program)

CheckDesignationComponentMarkingCategoryOrientationNotesCircuit
L10-coreT25-6 toroid coreyellow yellowToroid  Band 4: 16-30 MHz
L11-coreT25-6 toroid coreyellow yellowToroid  Band 4: 16-30 MHz
L12-coreT25-6 toroid coreyellow yellowToroid  Band 4: 16-30 MHz
wire 4#30 enameled magnetic wireMisc  Band 4: 16-30 MHz
C1627 pF 5%27JCeramic  Band 4: 16-30 MHz
L122 uH 27T #30 on T25-6 (16")yellow yellowCoil  Band 4: 16-30 MHz
C17100 pF 5%101 101Ceramic  Band 4: 16-30 MHz
L102 uH 27T #30 on T25-6 (16")yellow yellowCoil  Band 4: 16-30 MHz
C1827 pF 5%27JCeramic  Band 4: 16-30 MHz
L110.53 uH 14T #30 on T25-6 (10")yellow yellowCoil  Band 4: 16-30 MHz

Band 4: 16-30 MHz Summary Build Notes

Band 4: 16-30 MHz Detailed Build Notes

Top of the Board

Band 4: 16-30 MHz Top View

Install the Capacitors

Per Jan, G0BBL, solder the Ceramic Capacitors with a clearance of 1/16" to 1/8" (2mm to 3mm) away from the PCB surface.

CheckDesignationComponentMarkingCategoryOrientationNotes
C1627 pF 5%27JCeramic 
C17100 pF 5%101 101Ceramic 
C1827 pF 5%27JCeramic 

Wind and Install the Coils

CheckDesignationComponentMarkingCategoryOrientationNotes
wire 4#30 enameled magnetic wireMisc 
L122 uH 27T #30 on T25-6 (16")yellow yellowCoil 
L102 uH 27T #30 on T25-6 (16")yellow yellowCoil 
L110.53 uH 14T #30 on T25-6 (10")yellow yellowCoil 

Band 4: 16-30 MHz Completed Stage

Top of the Board

View of Completed Top

Band 4: 16-30 MHz Testing

Visual Check

Test Setup

Using very good lighting and magnification, carefully inspect the solder joints to identify bridges, cold joints, or poor contacts.

Pay especial attention to the joints on the inductors. If necessary, touch up the joints with your iron and/or some flux.

Continuity Tests

Test Setup

  • This tests for continuity in the "chain" of inductors for this band
  • The graphic below shows two continuity chains and their associated test points on the bottom of the board.
  • The "A and B chains"are shown using lettered dots and lines. :
  • For each of the two segments (A-A and B-B), measure the resistance between the dot pairs - you want ~0 ohms.
Continuity Tests

Test Measurements

TestpointUnitsNominal ValueAuthor'sYours
Point A to Point Aohms00_______
Point B to Point Bohms00_______