Tube Adapter for the Tektronix 575 Transistor Curve Tester

The Tek 575 Transistor Curve Tester can be used to measure tubes like the twin triode 12AX7 (which has a 12V heater requirement) and the 6DJ8 (which uses 6V at the heater). The 575 can sweep collector (plate) voltage between 0 and 200 Volts, which is a useful range for these tubes. All the 575 is missing is a heater supply, and a suitable tube socket.

I constructed a tube adapter that can plug in to the banana plug sockets on my 575’s DUT panel, using a panel from a parts 575 I acquired years ago (to replace the bad CRT tube in my original 575). The angled faces on the panels combine to result in a horizontal surface, which I used to mount the tube socket (B9A), a pair of terminals for an external heater supply (I used a 6VDC wall wart adapter rated at 300mA), and a single pole double throw (SPDT) switch to select between 12V and 6V tube types.

Here is the completed adapter, measuring the transfer curves for a 12AU7A dual triode.

Tektronix 575 Tube Adapter

One convenient aspect of the wiring in the adapter is that the tube’s two triodes can be compared easily by flicking the 575’s transistor A/B select switch. This allows an instant comparison of the transfer curves, and shows how well (or badly) they match.


2 thoughts on “Tube Adapter for the Tektronix 575 Transistor Curve Tester

  1. Saw your Tek Page that you are looking for a 1A4 & T Plug-In that I have 0ne of. No email to respond to on that site. Would like more info on your 575 Tube curve tracer board. I used the Tek Tube curve tracer back in the early ’60’s at Tung-Sol.
    Regards Bobz


    1. I based the circuit on the one this guy uses: tek 575. It’s very simple, as I recall, but don’t have the details in front of me.

      The Yahoo! Tekscopes group is a great resource for these older ‘scopes.



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