A design with opto isolation by Gary Dion.
He writes in May 2001:

I built one of the designs (the one by Nigel, KG7SG) and it worked great. However, being the paranoid type I decided to design my own electrically isolated version. I figure it would be preferred in a field day situation with questionable rig grounding.

The biggest challenge was powering the optos on the radio side. The 8v line coming from the 706 can source at most 10 mA (per spec). This design pulls an average of less than 0.5 mA. This voltage can be pulled from either the ACC connector or the michrophone jack. If the microphone jack is already being used, it is likely connected to an isolated audio interface. Many isolated audio interface degins already exist, so I decided not to include that on the schematic.

I love being able to find -and share- all this stuff on the web... -Gary if-gary.gif - 9818 Bytes