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EICO 628 Vacuum Tube (Valve) Emission Tester


EICO 628 Vacuum Tube (Valve) Emission Tester

The EICO Model 628 tube tester was the updated version of the earlier EICO Model 625 tube tester. Like the EICO 625, the model 628 is an emission tube tester which is useful in determining the condition common vacuum tubes. The EICO 628 tube tester is not capable of measuring the transconductance of a tube. An emission tube tester like the EICO 628 cannot be used to "match" tubes. For matching vacuum tube you will need a tube tester that can measure dynamic conductance, like the EICO Model 667 tube tester.

EICO 628 Vacuum Tube (Valve) Tester

Photograph 1: EICO 628 Vacuum Tube (Valve) Tester

Now while the large array of controls may look intimidating, the EICO 628 is not difficult to use. On the left left of the unit is the meter "Shunt" and the "Line Adjust". On the right is the filament voltage switch and the "selector" switch, which begins to arrange the socket to the virtual diode circuit, and place the meter in the appropriate path. The lever switches on the bottom complete the setup, and also perform the "Shorts" test. A scan of the instructions manual for the EICO Model 628 tube tester is available for viewing and download at the bottom of this page.

Closed Cover - EICO 628 Vacuum Tube (Valve) Tester

Photograph 2: Closed Cover - EICO 628 Vacuum Tube (Valve) Tester


Instructions Manual and Tube Data Chart - EICO 628 Tube Tester

The instructions manual is from the BAMA web site. Check out their archives for more hard to find tube manuals.