I desperately need to test some directly heated valve rectifiers. Would it be OK to use a bench power supply for the heater and connect the anodes to a variac and simply plot the current with a multimeter?
Would I need to add resistance on the cathode? I'm slightly worried that there's no isolation between the variac and the bench supply / multimeter.
Would I need to add resistance on the cathode? I'm slightly worried that there's no isolation between the variac and the bench supply / multimeter.
Rectifiers can be tested in a number of ways, the Funke tube testers put 50 or 100 vac directly across the rectifier and measure the current whit an analog meter.
Depending on where you live you could use a simple variac coupled to an insulation transformer, then use a DVM to monitor the AC voltage, and a DC ammeter to measure current. You can use the Funke test cards to determine what voltage you need, and what the minimum current is.
Beware that because your testing rectifiers its advisable to use centertapped AC heating, because otherwise one end of the fillament will be at a lower potential.
Depending on where you live you could use a simple variac coupled to an insulation transformer, then use a DVM to monitor the AC voltage, and a DC ammeter to measure current. You can use the Funke test cards to determine what voltage you need, and what the minimum current is.
Beware that because your testing rectifiers its advisable to use centertapped AC heating, because otherwise one end of the fillament will be at a lower potential.
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