Projects for the amateur radio engineer. Hardware, software, electronics and test equipment for the amateur community.
The heart of this transceiver is an ATmega128 microcontroller (MCU). It controls the vast majority of functions within the radio. E. g.: Frequency generation of the 2 DDS systems, audio tone and AGC decay time, T/R-switching, the presets for transmitter gain on the 6 bands independently, display and panel lights etc. etc. And, due to…
The two DDS oscillators are mounted to the side of the cabinet. They are sited close to the microcontroller board to keep leads short. Right on the left you can see the small dual-tone oscillator for testing and tuning. Next is the AD9834-equipped local oscillator (LO), centered the AD9951 that serves as the VFO. Right…
Abstract An SSB radio for the HF bands will be presented. Featuring 12 to 20 Watts of output power (depending on DC supply), full DDS frequency generation, covering 6 major frequency bands (1.8, 3.5, 7, 14, 21 and 28 MHz) within the short wave amateur radio spectrum. The rig also features colored LCD and front…
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…
In this paper we will discuss a single sideband amateur radio transmitter/receiver for the 40 meter band that has been designed to ensure good performance characteristics with reasonable number of parts (no “overkill” in component use), particularly concerning the receiver. Circuit simplicity and over-average performance were to be combined. The background: Some years ago I…
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)…