c) It is normal for the 125MHz reference oscillator (metal can on the right) to get hot in operation.
5. Hardware Options
5.1 Explanation of connections
The table to the right details the
purpose of the connection points
around the right-hand and bottom
edges of the PCB. The pin-spacing is
0.1-inches and a suitable connector
could be used if desired. These are
further described in the following
sections.
Note that the cluster of connections at
the left board edge are for fitting the
connector to the relay-switched LPF board kit. They can be ignored for now.
Connections A0, A1 and A2 allow options concerning the LCD backlight, as described below. For basic
operation, simply connect A0 and A1.
5.2 Connection for basic operation
For the most basic operation of this kit as QRSS transmitter using 5V supply, it needs only a power supply
and RF output connection.
To allow use of a higher voltage
supply for the PA, the PA voltage is
not connected to +5V on the PCB. So
to run the transmitter using the 5V
supply, be sure to connect a wire
between the +5V and PA pins, as
shown by the short red vertical line in
the diagram (right).
5.3 Alternative button mounting option
If you wish you may use an external pair of buttons to control
the kit. The button input signals are available at the edge of
the board, labelled S1 (left button) and S2 (right button). The
buttons should be of the push-to-make variety. The left button
should be connected between the S1 signal and ground;
similarly the right button should be connected between the S2
signal and ground.
9
Label
Group
Description
5V
GPS
+5V supply to GPS module
Gnd
GPS
Ground connection to GPS module
RxD
GPS
Serial data input from GPS module
Pps
GPS
1 pulse per second input from GPS module
Tune
Future
No connection – for future enhancements
Sin
Options
RF output from DDS, 1V p-p sinewave
Out
Options
RF output from DDS, 5V p-p squarewave
S2
Buttons
Optional external button S2, switch to Gnd
Gnd
Buttons
Ground for optional external buttons
S1
Buttons
Optional external button S1, switch to Gnd
Gnd
Power
Ground connection to Power supply
+5V
Power
+5V power supply
+PA
Power
PA power supply – may be connected to +5V
Gnd
RF
Ground for RF output
RF
RF
RF output
