We wish to make our own cheap Conducted Emissions test kit for our 50-250W UK mains powered LED luminaires. We don’t need perfection. We are trying to make a LISN. The inductor in the LISN is to be 50uH. This inductor is supposed to be air core, made by hand winding over plastic drum . The inductor should feature damping resistance along the coils to reduce ringing due to the inductors self resonant frequency. However, if we just pick say an inductor with a SRF of about 7MHz, then does that mean that our readings of conducted emissions will be OK up to around 5MHz? Also, suppose we want an increased SRF, then can we just solder in series a load of say 3uH inductors till we get to the 50uH value (then the SRF will be higher)
Making a LISN…
**broken link removed**
At the moment we have picked this inductor...
http://uk.farnell.com/coilcraft/pcv-...-10/dp/2457647
The LISN diagram of the above link document (page 2) shows an input filter as well as the LISN. Does the input filter have to have these exact component values. (L2 = 250uF and C2 = 4uF)
Also, it says that the L2 inductors are coupled inductors (common mode choke)….but I thought the LISN was also supposed to be able to measure common mode emissions?
Also, for measuring common mode emissions, I presume the kit has to be able to allow measurement of 100MHz plus? Common mode conducted emissions, as I understand it, are rarely prevalent below about 10MHz?
Also, how do you make a LISN that can allow common mode emissions measurement? Do you have to use a coupling network out of coupled coils?
Also, presumably there are problems when measuring common mode emissions because the signal level will be extremely low….so I presume some kind of broadband RF amplifier will be needed for its measurement?
Also, if we dont make it in a metal box, (instead use plastic) then to what frequency will the LISN be effective up to?
Making a LISN…
**broken link removed**
At the moment we have picked this inductor...
http://uk.farnell.com/coilcraft/pcv-...-10/dp/2457647
The LISN diagram of the above link document (page 2) shows an input filter as well as the LISN. Does the input filter have to have these exact component values. (L2 = 250uF and C2 = 4uF)
Also, it says that the L2 inductors are coupled inductors (common mode choke)….but I thought the LISN was also supposed to be able to measure common mode emissions?
Also, for measuring common mode emissions, I presume the kit has to be able to allow measurement of 100MHz plus? Common mode conducted emissions, as I understand it, are rarely prevalent below about 10MHz?
Also, how do you make a LISN that can allow common mode emissions measurement? Do you have to use a coupling network out of coupled coils?
Also, presumably there are problems when measuring common mode emissions because the signal level will be extremely low….so I presume some kind of broadband RF amplifier will be needed for its measurement?
Also, if we dont make it in a metal box, (instead use plastic) then to what frequency will the LISN be effective up to?