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5.1
Power connections
Connect a well-smoothed, clean DC power supply. Refer to your chosen power supply option (see section
4.3). For the recommended assembly with the LM317LZ voltage regulator acting as 5V regulator on the
ProgRock board, the input supply voltage should be in the range 7-12V.
5.2
GPS connection
If you connect a positive-going, 1 pulse-per-second (pps) signal from a GPS receiver such as the QRP
Labs QLG1 GPS receiver kit, then ProgRock will automatically use this to discipline the Clk0 and Clk1
outputs.
IMPORTANT: When not in use, connect the 1pps input to Ground! Receivers with a very
short pulse e.g. 10us will not work (for example, Trimble Thunderbolt).
The Si5351A Synth module’s Clk2 output is used by the microcontroller to count the frequency of the
Si5351A’s 27MHz reference crystal. The processor makes corrections to the configuration of the Si5351A
synthesiser to compensate for any error or drift in the 27MHz crystal oscillator. It takes a few minutes to
get the ProgRock output frequencies accurate within 0.1ppm. Calibration is faster on subsequent uses.
When using GPS discipline, the Clk2 output is NOT available for normal use. The configurations which are
entered for the Clk2 output are simply ignored. To use Clk2 again, you must disconnect the GPS 1pps
signal, and switch off/on the power supply to ProgRock to cause a system reset.
