From the QRP School YouTube page...
This comprehensive video explains the concept behind amateur radio digital modes and describes the hardware and cabling required to get started. This video lays the groundwork for future, in-depth videos that will demonstrate RTTY, PSK31, JT65, and Winlink.
I explain the audio cables that are required for those who want to make their own cables. I also show the inner workings of a Signalink box and recommend that most people purchase a Signalink or Rig Blaster external sound card in order to resolve the audio and push-to-talk cabling issues.
Here is a link to the QRP School YouTube Channel !!
QRP SCHOOL ON YOUTUBE