1MP 5687 Calvertron NOS NIB made in U.S.A Amplitrex tested #2921001 2921002
1MP 5687 Calvertron NOS NIB TOP D getter made in U.S.A Amplitrex tested. NOS NIB 5687 Calvertron. Tested Advance Digital Tube Tester Amplitrex AT1000. Like Amplitrex AT1000 Advance Digital Tube Tester.
