ozQRP MST3 Construction And Operation Manual page 31

Step 7: Transistors
The 2N3904 transistors are orientated to match the screen silk component overlay. The BD139
pins are shown below:
Leave the IRF510 and IRF4905 power MOSFETs and the voltage regulator installation till
later.
Step 8: Connectors
The MST3 board utilizes polarized pin headers for most external connections. If preferred the
wires may be soldered directly to the PCB, but the connectors make for a professional looking
build, plus allow easy disconnection and testing if required. The connectors have a vertical
polarizing piece and the connectors are installed with this piece towards the centre of the PCB.
The power connector is a 2 way screw terminal block and the terminal openings face towards
the edge of the PCB.
Install the 8 pin IC socket for the ITM.
Step 9: Filter headers
The plug-in filter boards use 2.54mm (0.1") pitch male/female connectors. The male connector
is soldered to the plug-in board while the female connector is soldered to the main PCB.
The LPF input and output connectors each have 4 pins. This allows the LPF to be inserted in
either way as the filter circuit is symmetrical.
The BPF boards have defined inputs and outputs and so use a 3 pin and a 2 pin connector to
ensure they are plugged in the correct way.
MST3 Construction and Operation Manual – Issue 1
E
C
Printing on front.
B
Page 31