***** Tested on our new proprietary  tester , the E3444 Triplett/Westmore 501 :

It's a Triplett 3444 / Westmore 501 that has been enhanced.

This tester uses regulated power sources for the bias, plate, & screen voltages, as well as modified operating & testing procedures.

Filament voltage is also controlled. 

Tubes are tested in accordance with the manufacturer's specifications; measurements closely align with a laboratory tester built to rigorously measure vacuum tube characteristics. 

Tubes can be accurately matched for gm & plate current at the manufacturer's specified test points or at other specified test points.

***** This tester was prepared by Mr. Paul Hart of Falls Church , Virginia. *****

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Industry Bogey transconductance = 1200/1200 µmhos 

       Industry Bogey plate current = 1.0/1.0mA

                                        Results = pictured