Category: DDS VFO

Programming the AD9834 DDS chip

This is a software project for building a VFO with the 75MHz clocked AD9834 synthesizer chip by Analog Devices. Due to the Nyquyst theoreme with a maximum clock rate of 75 MHz a frequency of 37.5 MHz can be achieved. When overclocking the chip to 100 MHz (which has been succesfully tested in many cases)…

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Improving spurious emissions performance in QRP transceiver DDS VFO: Replacing AD9850 by AD9951

The next step in improving my homemade QRP multiband transceiver was to reconstruct the DDS VFO. This was not urgently neccessary but after some months of continously operating the rig I was not 100%  satisfied with the spurious performance of the AD9850. The AD9850 is a DDS device with only a 10-bit digital-analog-converter (DAC). These…

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