DDS VFO 2 Construction Manual – Issue 1
Page 15
6
F
IRST TIME POWER ON
Before applying power check the board over one more time. Look for solder bridges and
components in the wrong way. A moment spent here may save a lot of frustrating time later on.
Once you are satisfied connect the DDS VFO to a power supply between 9 and 15V DC. If the
power supply has current limiting set this to about 100mA.
Apply power and check that the LCD backlight turns on. Also check with a multimeter that the
output of the regulator is between 4.75 and 5.25V DC. The power supply current should be
around 50mA. If the LCD installed is not the one supplied in the kit the current may be different
depending on the backlight characteristics.
If the readings are way outside this range turn off immediately and look for problems.
At this stage you may or may not see anything on the LCD. Most likely this is because the LCD
contrast has not been set. Adjust the contrast trimpot until the characters are clear and easy to
read.
Turn the power off then on again and check that the first thing displayed is the firmware version
number. This is then followed by the operating display.
As the DDS VFO has not been configured the LCD will display default settings. These are
frequency of 7.1MHz and a 1KHz Step. Verify with an oscilloscope or a frequency counter that
the DDS is outputting a 2.9MHz sine wave signal of around 300mV pk-pk.
Содержание DDS VFO 2
Страница 1: ...DDS VFO 2 Construction Manual Issue 1 Page 1 DDS VFO 2 CONSTRUCTION MANUAL ...
Страница 7: ...DDS VFO 2 Construction Manual Issue 1 Page 7 Figure 1 CPU ...
Страница 8: ...DDS VFO 2 Construction Manual Issue 1 Page 8 Figure 2 DDS generator ...
Страница 9: ...DDS VFO 2 Construction Manual Issue 1 Page 9 Figure 3 LCD Rotary Encoder and Power Supply ...
Страница 14: ...DDS VFO 2 Construction Manual Issue 1 Page 14 Figure 4 Component overlay ...