ozQRP MST3 Construction And Operation Manual page 35

Step 13: Crystals
The crystals have been closely matched in frequency, so they can go in any position. The PCB
has a solder mask which should insulate the crystal metal cases from the PCB tracks, but to be
sure mount them slightly above the PCB. Once the crystals for the filter are installed solder a
wire across the top of the metal cases and down to a spare pad in the PCB groundplane set aside
for this purpose. The carrier oscillator crystal also has a PCB ground connection hole adjacent to
the crystal.
Step 14: Antenna wires
The antenna wires are difficult to solder to the pads once the PCB is installed in the case so
solder short lengths to the ANT and GND pads now. As the length is quite small you can use
hook-up wire and twist them together or use shielded cable if preferred.
Step 15: Power MOSFETs and regulators
The reason the larger regulators are left to last is simply because they sit high and near the
edges and may get damaged as the PCB is turned over and back as other components are being
installed.
The 7808 voltage regulator is installed with the metal tab facing to the edge of the board.
Mount the IRF510 MOSFET with the metal tab facing towards the edge of the board and with
about 5mm of lead length between the board and body.
The IRF4905 MOSFET is positioned so the metal tab faces towards the middle of the board.
Install the 78L08 8V regulator (REG1) and 78L05 5V regulator (REG2) as shown on the
silkscreen component overlay.
It is very important to check that the 78L05 regulator is inserted next to U1. If the 78L08 is
installed here, the ITM will be destroyed.
MST3 Construction and Operation Manual – Issue 1 Page 35