Category: AD9951

Constructing a high performance transceiver for voice communication on 14MHz

  Abstract A general and good practice in engineering is a steady process of improvement. This  article describes the construction of a high performance transmitter/receiver for SSB (voice) communication covering the 14MHz (20 meters) high frequency amateur radio band. Various modules that have proven high performance, liability and ruggedness in recent constructions will be combined…

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DDS and spurious signals – The role of the post-DDS-amplifier (Part I)

Abstract When building a direct-digital-synthesis (DDS)  frequency generator, the engineer has to take into account one inherit shortcoming of this state-of-the-art technology: Spurious signals that are an unwanted product of generating a radio frequency signal with a synthesizer. These signals occur in a wide range of frequencies and are a limiting factor for receiver performance…

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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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