i have the chance to buy a hikok 600 tube tester. right now i have a B&K 707 and a 1-177B. i use the 1=177B for the older tubes and the b&K for the other ones but certain tubes wont test on a B&K 707 correcly like the 6sl7 or the 12ax7. will the hikok 600 test 12ax7 type tubes and is it a better tester then the B&K i have.