2
2.2 VFO tuning mode
14,060,050
The rotary encoder tunes the Clk0 output frequency. The tuning rate is indicated by the underlined
digit of the frequency display. In the above example the frequency is 14.060050MHz and the tuning
step is 100Hz.
Note that the lower frequency limit of the Si5351A synthesiser chip when using the supplied 27MHz
reference crystal, is 3.515kHz. The upper frequency limit has been found to be approximately
292MHz. The register configuration allows higher frequencies to be set but the chip refuses to output
any frequency above 292MHz. The Si5351A datasheet specifies an upper frequency limit of 200MHz.
The practical upper limit may be lower depending on your application, since at such high frequencies
the spectral purity of the output is degraded; furthermore the minimum tuning step becomes wider
than the 1Hz resolution of the tuning control.
Control functions:
Rotary Encoder:
Tunes the frequency in steps indicated by the underlined digit
Left button:
Enter “Select preset” mode
Right button:
A brief press enters the “Configuration menu editing” mode
Right button hold:
Press and hold, to enter “Select tuning rate” mode
2.3 Select preset mode
14,060,050
Pr.0 010,000,000
Use the rotary encoder to cycle through the presets which you have set up, in the configuration
menu. To choose a preset to load into the VFO, press the right button. To cancel preset selection
mode and return to VFO tuning mode, press the left button.
Control functions:
Rotary Encoder:
Scroll up and down through the list of configured presets
Left button:
Cancel “Select preset” mode and return to VFO tuning mode
Right button:
Load the selected preset into the VFO, and return to VFO tuning mode
