As a special treat for all radio amateurs we present a general-coverage AM/FM/SSB receiver with a wide range of features, which uses a DDS chip in the VFO section and also has a DRM output that can be fed into a computer. The receiver is controlled by a modern 8-bit Atmel RISC processor. The frequency readout is on a clearly legible 7-segment LED display.
Although the AT90S8515 used in the project is no longer recommended for new designs, it is still generally available (December 2006). A suggested replacement is the ATmega8515, which offers AT90S8515 compatibility thanks to its SC8515 compatibility mode fuse.
Inductors L11 and L14 have been transposed on the component overlay. This may be corrected by transposing the component references in circuit diagram Figure 2. In the components list, L11 should be marked as 1μH2.
The PCB design has a length of copper track missing at pin 19 of the MAX7219. The connection should be made with a piece of wire. Updated Gerber files were sent to ThePCBShop on 2 March 2007 The corrected parts list and PCB artwork (pdf file) may be downloaded from our website.
Depending on the response of the readout to fast turning of the rotary encoder, and the encoder used, the value of capacitor C40 may be changed a little.
Although on MIX1 the marking is with pin 6 instead of pin 1, the device can be mounted as shown because of its internal symmetry.
For SSB reception, the amount of frequency pull that can be obtained from the CSB455 device (X3) will depend on the exact type and brand. The CSB455 supplied by Barend Hendriksen and used in our prototype gave good results. Suggested methods of obtaining sufficient pull from nondescript CSB455 devices may be found on our Forum.
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