Precision Tube Tester 612 and 614 Operating Instructions Sorry, this product cannot be purchased. $7.99 Category: Precision Apparatus Company Related products Precision Apparatus EV-10A Vacuum Tube Multi-Meter Manual $8.99 Read more Precision Tube Tester 10-60 Operating Instructions $9.99 Read more 1953 Precision Apparatus E-200 Servicing by Signal Substitution Manual $10.99 Read more Precision Tube Tester 10-12 10-15 Operating Instructions With 1974 Tube Data $10.99 Read more