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On 2/27/19 8:51 AM, Daniel Kunkel wrote:
Hello list,
I recently exceeded the 20 amps of a commercial line filter. I don't think
I let the magic smoke out, but is there a way to verify it is still
working? I am thinking of just using a signal generator and oscilloscope to
see how much it is attenuating.
That would work - you could look up the spec sheet and see what it's
supposed to be.
There's a "differential mode" attenuation (line to line) and a "common
mode" attenuation spec. (line to ground)
If you overcurrented it, the most likely failure mode would be an open,
from melting the wire in the series inductor.
A failure of the shunt capacitor would be from overvoltage.
The real challenge is the dynamic range of your measurement. If your
signal generator puts out +10 dBm (that would be 0.707Vrms into 50
ohms), and the filter has 20dB of attenuation, you'd expect to see
-10dBm into a 50 ohm load resistor. You're looking at measuring 70 mV
rms on the scope..
Now, if you happen to have a little VNA sitting around, that makes life
easier.