Shack Mains Filter

Why the need?

Having watched the excellent video by Ian White GM3SEK on reducing emc problems in the shack (available on YouTube) I thought I would knock one up. Even if it doesn't cut down all the noise it should help to minimise any rfi I may generate.

The Parts

The fundamental element in this mains filter is the Fair-Rite clamp on ferrite (part number 0431177081) which I ordered from Mouser. Just slightly digressing, I was very impressed with the service from Mouser. I ordered three of the cores on the Tuesday and they were delivered on the Friday; the vat and duty were all sorted by the sender so no having to sort out money with the tax man. The second part of the cleaner upper is a ten amp mains filter purchased from Discount Devices through their eBay shop. I regularly purchase components of all different types from them and have never had a problem with any of the transactions.

Obviously safety is of paramount importance in the shack and a suitable heavy duty enclosure with 20mm cable glands would be the ideal. Originally I thought that I had a suitable box to house the filter. My mistake! A trip to Screwfix resolved the problem of housing the filter in following the hasty procurement of one of their electrical boxes and I also got two glands for the cable entry and exit. The cable was part of an extension lead that was lying around in a box in the shack.


A long length of the three core cable (the bit with the plug on) had the outer insulation stripped back and the three cores were twisted fairly tightly before being threaded repeatedly through the core. Some insulating tape was wrapped round the choke to keep the winding in place and to prevent the core coming apart. This cable was then connected to the filter (on the line side) and the double socket's cable wired to the outlet (load). Both cables were fed through the respective cable glands to prevent the insertion of any foreign objects.


Not tried it out yet!