What I am proposing is a cheaper version of the MSD tester. Something that will do the same job but for a much lower price. Hopefully at a price that would be attractive to the DIY Porsche guy who needs to trouble shoot a CDI system once or once in a while.
The testing could be on a workbench with a CDI unit, a coil, 12 VDC, and a test plug.
The test plug could be one like this:
Or and adjustable one:
You would attach this test plug to the output of the coil. The proposed signal generator would provide the "points" or ignition signal.You can visually see the spark that the system is putting out.
Of course this could be done with the components in the vehicle and the engine not running. If it operates properly, you know your CDI and coil are operating.
As mentioned the points or trigger input can be measured with an AC volt meter.
I am not proposing a one shot tester that will light up status lights. that would be nice, but you would never recoup you development costs due to a limited market.