ozQRP MDT, Construction Manual

Page: 22 / 42

MDT Construction Manual – Issue 2 Page 22
9.2 B
UILDING THE
PCB
It’s advisable to print out the parts list and tick off the components as they are installed. The
PCB has a silkscreen component overlay with components designators, but you might like to
print Figure 20 as an additional reference when installing the components.
Step 1: PCB
Remove the PCB from its protective bag. The PCB comes shipped with the SMD dual tuning
diode pre-installed. This is the only SMD device in the kit.
Step 2: Resistors
The resistors are all 5% ¼ watt types with easy to read colour bands.
If in any doubt about reading resistor values measure them with a multimeter first.
Pass the pigtails through from the top and bend out slightly underneath to hold them in place.
Turn the PCB over and press down slightly to press them against the surface and solder. Cut off
the excess pigtail with side cutters.
It is easier and less confusing to install a group with the same value rather than to cover a
section of the PCB with mixed values. You will also find it more convenient to install 5 or 6
resistors at a time rather than inserting them all before soldering as the pigtails will more than
likely get in the way.
Step 3: Diodes
See Figure 9 to identify the positive or Cathode end of the diodes before installation. The small
Zener diode looks like a signal diode so make sure you don’t get it mixed up. You may need a
magnifier to identify them correctly. Form the leads before inserting to reduce stress on the
body when pulling through the PCB.
Figure 9 Diode identification