NOTE: Photos below show PCB revision 1, but they are very similar!
1) Solder in the socket for IC1.
To avoid confusion or mistakes later, align the
dimple at one end of the socket, with the
dimple illustrated on the PCB. The dimple
should be at the end nearest the right-hand
edge of the PCB.
2) Solder in all capacitors and the quartz
crystal (note there is no C7).
Be careful not to mix up the 22pF and 10nF
capacitors. The two 22pF capacitors are the
ones on each side of the crystal.
3) Fit and solder switches S1 and S2, if not
using off-board switches.
The switches are in a convenient location to
press with your left and right index fingers
when holding the module in your hands, with
the LCD facing you. However, it is certainly
nicer to fit off-board switches as well, on a
front panel (see later “hardware options”
section).
4) Wind and install the toroid
The toroid can be mounted horizontally or
vertically. I prefer the horizontal method as
there is enough space for it, and it keeps the
toroid away from the LPF module which is
plugged in above. When winding the toroid,
remember that each time the wire goes
through the centre of the toroid counts as one
turn. 35cm of wire should be enough for 25 turns. Trim the ends of the wire, scrape the enamel off
and tin them with solder. As an alternative to scraping the enamel off, the wire ends may be held in
a hot blob of solder on the iron tip for a few seconds, and the enamel will bubble away. Check
continuity on the board with a DVM.
5) Solder the sockets for the DDS module and
the low-pass-filter board.
Some care needs to be taken with the
alignment, to ensure that there is a good fit
when the plug-in boards are added. One
method is to build the LPF kit board first, and
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