Author Topic: Some Mods for the Delta 44 sound cards.  (Read 3180 times)

Anton Janovsky (ZR6AIC)

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Some Mods for the Delta 44 sound cards.
« on: February 09, 2014, 09:44:18 am »
The ground loop error (ref http://www.nitehawk.com/sm5bsz/linuxdsp/hware/delta44.htm)

The Delta 44 soundcard is sensitive to loops in the ground connections between the computer and the analog radio hardware. Even with careful star grounding it is difficult to avoid strong signals at mains frequencies. The computer itself may produce pretty large signals due to potential differences between different parts of the chassis. The ground loop is easily eliminated by cutting the connection between the two screws holding the 15 pin d-sub connector and the analog ground plane of the PCB itself. Look here for performance measurements for different modifications of the Delta 44.
Power supply noise

With the high dynamic range of the A/D converters it is utterly important to have extremely well decoupled supply voltages. performance measurements for different modifications of the Delta 44 shows the modifications I found suitable on my own Delta 44 card when adding them one by one. Modifications interact and the final solution is a little simpler but the result is the same.

Read more about it at http://www.nitehawk.com/sm5bsz/linuxdsp/hware/delta44.htm