Main Board Construction; General - ozQRP MST3 Construction And Operation Manual

7 M B C
AIN OARD ONSTRUCTION
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ENERAL
The MST3 is built on a high quality fiberglass PCB. The PCB is double sided with the majority of
the tracks on the bottom side with the top side forming a ground plane.
To assist construction the component overlay is screen printed on the top side and a solder
mask is included to help guard against solder bridges.
The ground plane is substantial and can sink quite a bit of heat from low wattage soldering irons
so ensure you use a good quality iron that can sustain the power required. You may find that
sometimes solder doesn't appear to flow through to the top side. This is not necessarily a
problem because the plated through holes make a connection to the top side automatically.
Another point to consider is that plated through holes consume more solder than non-plated
holes and makes it more difficult to remove components. So check the value and orientation of
components before soldering!
There isn't a 'best' scheme for loading the components. If desired you can build sections at a
time and test them out, but it is not really necessary and in any case some sections rely on
others before they will operate. The suggested procedure is to load the smaller components and
those that sit closest to the PCB first. This includes resistors and diodes, and then work
upwards, leaving the electrolytic capacitors and the TO220 devices till last.
If you did want to build and test stages one at a time, you would need to first install the power
supply components and the relay to allow voltage around the board.
MST3 Construction and Operation Manual – Issue 1 Page 27