My Projects......


Sound Card interface.


The Logger32 logbook program I am using provides for a CW keyer, PSK/RTTY input and output and a voice recorder.

To use these facilities effectively there is need of a good interface to insulate the radio circuits from the computer. Not only to prevent ground loops but also RFI.


This is the sound card interface that I built (autumn 2006) It fits in an empty slot in the tower model desktop computer. I have a separate output at the front for general use and I can switch the microphone and I/O by hand as well as by software. The DB16 connector goes to the radio. It connects to the keyer input, the PTT and the audio input and output channels.






sound card interface in drive slot in computer

Click on the picture to view it in a larger format.

Vero board of the  interface

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This is the perf-board with the interface behind the computer front. Power is taken from the computer. The line-in level of the sound card needs about 0.5V tt and the output from the FT1000MP is lower than that so two simple op-amps take care of that. The whole system is galvanically insulated from the radio. The audio channels with 1:1 600 Ohm transformers and the RST (CW keyer) and DCD signals by relais.


I do not think I bought anything for this interface: all components come from the junk box. The transformers can be found in obsolete computer modems and most other components were scavenged from PC boards in my collection. Sorry RigBlaster but you will not sell anything to me.

If you are interested in one of my projects, the components used or more details than given on these web pages you are welcome to contact me. Please feel free to use the web mail facility on this web site.

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