We have selected three products to try:
|MANUFACTURER||PRODUCT CODE||PRICE (*)||PHOTO||PLOT|
|TE Connectivity||6EMC1||16.90 EUR|
The price shown here is the price of the products for a single piece, at the distributor TME, it may vary, and the same product could be available also from other distributors.
The characteristic of the 6EMC1 is provided only up to 30 MHz, so we don't know how the filter behaves at 100 MHz, or more. From the available plot it seems that the characteristic is flat also for a certain range beyond 30 MHz but the attenuation has to diminish at some higher frequency. Many sources of electromagnetic noise produce noise in the 1 MHz - 30 MHz range so the 6EMC1 may be good in these cases, but when we suspect that the noise could be at a higher frequency we have to choose another product. The 6EMC1 is also bigger than the other two selected products. The schematic printed on the filter enclosure represents a two-stage filter, which is in agreement with the attenuation values of 80 - 90 dB. This filter is designed for a maximum current of 6 A, which can be even too much in many home and office uses, but we selected it because the smaller versions were not immediately available.
The two Schurter products that we selected report their attenuation up to 400 MHz which is good for when we are not sure about the frequency band of the noise. The attenuation is 50 - 60 dB and has some peaks and lows when the frequency approaches the hundreds of MHz, but anyway the filter seems to provide some useful attenuation in this frequency band too. These two filters are quite small in size, which is useful when there is little room to install them. These two filters support a current of 1 A which is certainly enough for a communication device.
Filters applied to ADSL systems