I built two testers. One that is similar tot he old tester with three meters and a shunt for measuring the current. I then built a modified one that uses a clamp type transducer for measuring the current.
The shunt gives more repeatable results in testing. I also tried one current transducer that said the specs were +/- 2 percent. It turned out to be 5 percent. The Temna probe seems to work OK and results are closer to the shunt results. It still reads a little high on the current.
