Jackson 648 tube testers

Anyone have any experience with the Jackson 648 tube testers? I am looking to test 6DJ8/6922/12AX7/6CA4/6SN7/7024/ tubes, etc. I read the recommendations on Hickok and B&K testers but there was no info on the Jackson tester. I want to get testing results and not spend to much on a tester. I see the Jackson testers for $100 with manuals and calibration instructions.

Thanks