directly heated diode

[Clemens Mug]

I bought an old Philips 836A radio. I’m currently restoring it.
The triode (E499) still measures (very) fine.
But I don’t understand how to measure a directly heated diode (1823). What settings should I use on the µtracer to reproduce this curve?  

[Emil Almberg]

Dont connect the catode, only the heater.

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[Sébastien D.]

Hello,

I have never measured a rectifier with a uTracer, but I suppose the procedure is possible with this device. Please check that what I describe is compatible with your uTracer.

To verify the emission capability of a rectifier, plotting its curve without adjusting the filament supply parameter is useless (unless you do not know its specifications).

People often do not know how to test a rectifier properly. However, the rule is simple: when reducing the heater voltage by 20%, the anode current should not decrease by more than 10% ;)

So forget about your curves and do the following:

• You must insert an anode resistor to limit the current to about 40 mA (the test will be done at 250 V, so about 5000 Ω).
• Test each element separately.
• Make a first measurement of the anode current with filament voltage = 4 V.
• Make a second measurement with filament voltage = 3.2 V (-20%).

If the current does not decrease by more than 10% for each element between the first and the second measurement, your rectifier is in excellent condition! If not, then it is worn out....

Have a good day :D
Seb