DDS VFO 2 Construction Manual – Issue 1
Page 5
1
I
NTRODUCTION
The DDS VFO 2 is designed as a companion for the MST3 transceiver board although it could be
used with many other Superhet or Direct Conversion radios. It is simple to use having only one
control yet offers many advanced features. A kit of parts, with the DDS chip already loaded onto
PCB and blue backlit LCD, is available from
DDS VFO Features:
1.
Stable frequency – no more drift!
2.
Simple to operate using a single rotary encoder control with press button switch.
3.
Bright 16 character by 2 line LCD display. Can also be used with a non-backlight display
to reduce current consumption if needed.
4.
Output frequency range of 10KHz to 10MHz. Frequency range can be extended by
‘overclocking’ (see text).
5.
Selectable 10KHz, 1KHz, 100Hz or 10Hz frequency steps.
6.
RIT control allows fine adjustment of receive frequency without affecting the transmit
frequency.
7.
Display of power supply voltage.
8.
Display state of USB/LSB and TX/RX inputs.
9.
Programmable IF frequencies. Separate high and low side IF frequencies ensure the
displayed frequency is the same as the transmitted frequency when changing sidebands.
10.
Programmable option to save the current frequency and step value into memory. These
are re-loaded at power up.
11.
Fine adjustment of frequency in configuration to allow for master clock tolerance.
12.
Voltage display can be trimmed in configuration to allow for voltage reference errors.
13.
Can be configured without an IF Offset to allow use as a signal generator or with Direct
Conversion transceivers.
14.
Draws only around 50mA at 13.8V DC (with LCD backlight).
15.
Spurious outputs at least -45dB.
16.
Typically 300mV pk-pk sine wave output (200 ohms).
17.
High quality double sided PCB with ground plane, plated through holes, solder mask and
silk screen.
18.
Simple and easy to build using through hole components apart from one SMD chip. To
assist constructors the PCB comes shipped with the SMD chip already installed.
Summary of Contents for DDS VFO 2
Page 1: ...DDS VFO 2 Construction Manual Issue 1 Page 1 DDS VFO 2 CONSTRUCTION MANUAL ...
Page 7: ...DDS VFO 2 Construction Manual Issue 1 Page 7 Figure 1 CPU ...
Page 8: ...DDS VFO 2 Construction Manual Issue 1 Page 8 Figure 2 DDS generator ...
Page 9: ...DDS VFO 2 Construction Manual Issue 1 Page 9 Figure 3 LCD Rotary Encoder and Power Supply ...
Page 14: ...DDS VFO 2 Construction Manual Issue 1 Page 14 Figure 4 Component overlay ...
