This project only was
possible by help of Michael, DG3SBD, Ivo, DL9MB/ OE6RIG
"Zusatztastatur für den PC mit programmierbaren Tasten" written by
Dr.-Ing Klaus Sander in FUNKAMATEUR, February 2008, page 163-165.
Circuit of audio vox has been created and published by DF3OJ.
for bringing this text into better English would be appreciated very