In the "old days" the VFO was shifted by mechanically switching a smaller capacitor in and out across the VFO tuning capacitor. This is probably why mark high was the standard, since adding capacitance would pull the frequency lower for the space tone.
Today we are mostly using synthesized VFO's, and apparently all that most rigs do is insert the tones internally instead of you having to do this with outside tones from a sound card or other interface device. The advantage is that you do not have to adjust anything, assuming the internal tones are set correctly. 73, Rick, KV9U Andrew O'Brien wrote: >OK, I think I get it but.. > > > >> With FSK, there is no setting up of the drive levels from the sound card >> since you are basically switching the frequencies from inside the rig. >> >> >> > > >tell me more about the above. How does the switching of frequencies >generate tones heard at the other end. > > > >
