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EICO 625 Vacuum Tube (Valve) Tester

EICO 625 Vacuum Tube (Valve) Tester

The EICO 625 is a very early and quite common tube tester which has long since been discontinued. In 1958 the EICO 625 listed for $34.95US. Now a reconditioned working EICO 625 tubes tester can be purchased for under $100US. The EICO 625 is an emission tester which gives you a basic idea of what condition the tube is in. One thing to note is that the EICO 625 test will not measure transconductance, so the test cannot be used to "match" tubes. For tube matching you will need a tube tester that can measure dynamic conductance, like the EICO Model 667 tube tester. The EICO 625 tube tester has many different tube sockets including ones for 4 and 5-pin tubes.

EICO 625 Vacuum Tube (Valve) Tester

Photograph 1: EICO 625 Vacuum Tube (Valve) Tester

Inside the EICO 625 tube testers there is a vacuum tube under the panel. The lone 6H6 diode is used to rectify one of the AC filament voltage for the neon indicator bulb used for identify "Tube Short". The EICO Model 625 tester was later updated to accommodate the newer tubes being developed during the 1950s - the updated model was called the EICO 628 Tube Tester.

EICO 625 Vacuum Tube Tester - Inside View

Photograph 2: Inside View - EICO 625 Vacuum Tube (Valve) Tester

Instructions Manual and Tube Data Chart - EICO 625 Tube Tester

Buying a Tube Tester

Most tube testers have long since been discontinued and a tester that is in good working condition may be difficult to locate. This particular unit was purchased from eBay and turned out quite well for us.