DDS Version 4 Build By G6AJW Dave Lucas G6AJW

Direct Digital Synthesizer VFO For Bitx

By C.V.Niras/VU3CNS

cvniras@hamradio.in 

The Project is publised in hamradioindia website



The DDS Version 4 is an excellent project for using with any tcvr. Many Ham's are now purchasing the PCB and building the DDS 4 Project.

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PIC16F628A and AD9850 or AD9851. PIC16F628A is an 18-Pin microcontroller

with 2K byte program memory, it is a FLASH-based and a member of the versatile PIC16F62XA family of low-cost, high-performance, CMOS, fully- static, 8-bit microcontrollers. PIC16F62XA devices have special features to reduce external components, thus reducing system cost, enhancing system reliability and reducing power consumption.

Features

1. Range 0 to 70 MHz by 1 Hz step.

2. Freq setting in 1, 10, 100Hz, 1, 10, 100KHz, 1, 10 MHz by using a low

cost mechanical encoder with a variable tuning rate. 3. 2 rows X 16 character LCD display.

4. A 4 x 3 Keypad used for easy freq entry.

5. IF, CW, SSB offsets settings when used with Transceiver/ Receiver. 6. Software calibration to WWV or equivalent. 7. Two VFOs and split freq operation.

8. 19 user memories, memories freq + mode (i.e. LSB/USB etc.)

9. All settings are held in EEPROM and are permanent (but user can

change it any time).

10. 4 Band selection and 4 Mode selection outputs.

11. When operating below IF frequency, clockwise rotation of rotary

encoder decreases DDS out put frequency but increases the display frequency.

12. RIT operation.

The PCB for the above project were designed by Tony Fletcher of UK and also mentioned earlier on this blog. Since then many have build the DDS. Hopefully we will be publishing the info as how the DDS
work's with the Bitx, but it is a complete solution for a multi band Bitx.

The Latest to build the DDS 4 is G6AJW  OM Dave Lucas from U.K who has very kindly granted me permission to publish pictures of his build DDS 4, he is also going to make the Bitx Vr 3 and hopefully very soon he would let us know as to how the Bitx 3 works with DDS Version 4.

 Here are the pictures of DDS 4 build by  . Dave Lucas G6AJW.

                                     

    Length= 203mm height =76 mm width =152mm

                     

   Inside View of the constructed DDS VER 4

  Front And Side View of DDS VERSION 4

     DDS VERSION 4  Build BY Dave Lucas .