DDS VFO Construction Manual – Issue 1
Page 13
7
O
PERATION
Power on
When the DDS VFO is powered on the version number is displayed briefly. This is followed by
the operating display shown in Figure 3.
Figure 3 Typical LCD operating display
Tuning
To tune the DDS VFO rotate the encoder clockwise to raise the frequency and counter-clockwise
to lower the frequency. The frequency will change by an amount equal to the Step value.
Frequency steps
To change the current frequency step press the encoder push button for less than 1 second and
release. Each press cycles through the available steps which are 1KHz, 100HZ and 10Hz.
Tuning Lock
To lock the encoder from changing frequency
press the encoder push button for more than 1
second. A lock message will be displayed on the upper right of the LCD.
To unlock press the encoder push button for less than 1 second.
Voltage Display
The power supply voltage is displayed in the lower right hand side of the LCD. This is updated
every 500mS. If the voltage falls below 8V a low voltage warning message is displayed to
indicate the power supply is too low for proper operation.
7.100.000
1KHz
13.8V
Transmit frequency
Power Supply Voltage
Frequency Step
