Filter Modulator ver2

Board information - version 2

PCBs supplied after 28 February 2017 are Version 2 and include the modifications to improve spectral performance.

Notes on the pictured example: Q01 not fitted (out-of-stock at the time), L50 replaced by hand-wound inductor (original lost in carpet) and R50A bridged to allow 5V input on J51.

General notes: Do not fit L10 or C11; they are not required if using a linear regulator. R33, R34 and R45 are not fitted as they are not required.

The Version 2 the parts list and schematics are available for download:

• xls parts list file - includes the extra components for V2

• Board layout

• Block diagram

• Block Diagram with IC Numbers

• Circuit schematic - part 1

• Circuit schematic - part 2

• Circuit schematic - part 3

Although the board includes the options to fit a switching voltage regulator (an R78E5), the regulator introduces spurs at -50dB on the output spectrum , so is not the recommended option.

DO NOT FIT L10 or cut the track beneath it as it does not suppress the spurs and introduces voltage drop, which upsets the modulator balance.