4. Construction
4.1 General construction tips
The kit comes as a main board, with pre-assembled DDS module, and a plug-in low-pass-filter module for
the desired band.
Since the low-pass filter module is a separate kit in its own right, please refer to
the separate instructions for constructing that kit.
Parts placement is defined by the printed legend on the PCB, so please observe it carefully, paying
particular attention to the correct orientation of the semiconductors.
The PCB is quite small and the parts are close together. You are recommended to use a low wattage iron
with a fine tip, and fine solder e.g. 1mm diameter or less. Take care not to overheat the PCB and risk
damaging it. A well-lit area and magnifying glass can assist. Be careful not to bridge solder across closely-
packed connections. Some of the joints are very close to each other. I recommend checking with a DVM to
make sure no solder bridges have been inadvertently created.
Note that components R2 and C7 are not required or supplied in the kit (R2 may be added by the builder if
lower LCD backlight brightness is desired). Q3 and Q4 are not supplied, additional BS170 transistors may
be installed here to increase the output power (see below). IC1 (the microcontroller) has an IC socket, in
case in future you wish to change the microcontroller e.g. for a firmware upgrade for new features, etc., or
in case you wish to program it yourself. Sockets are provided for the DDS module and the low-pass-filter
module.
4.2 Construction steps
Please refer to the parts placement diagram below.
Pay special attention to the orientation of the semiconductors. For IC1, the dimple in the PCB silkscreen
must be aligned with the dimple at the top of the IC socket and the IC.
The order of construction is not important but a good principle to follow is to install the smaller components
first, so that the larger ones do not prevent easy access. One suggested order of construction is described
below and I'd recommend following it carefully.
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