A large proportion of interference on 160, 80 and 40m bands seemed to be local switched mode power supplies, motors and motor controllers, so I set about looking at projects had already been worked on. I didn't have to look much further than the work by GM3SEK on his Clean up your Shack presentations, links below ;





I built this based on the above information sources, and assembled with the parts listed (Links and Prices correct as of 1/12/2020)

Total build cost, £75 plus 2 build hours.

Could be cheaper by replacing the RFI filter with a single stage item, which would be £15 less.


My Mains Filter

Picture of the Mains Filter, completed in a suitably sized IP65 enclosure


Picture of completed enclosure and 4w power cable 


Mains Filter Parts and Sources

Part Ref Source Price (2020)
Schaffner Chassis Mount RFI Filter FN2090-16-06 https://uk.rs-online.com/web/p/power-line-filters/1704906/ £33
Fair-Rite Openable Ferrite Sleeve 0431177081 https://uk.rs-online.com/web/p/ferrite-sleeves/4669164/ £14

20A Screw Terminal Blocks or Wago Terminal Blocks



2.5mm Ring Main Cable @ 1m   Require 2 x 1m length (Twin and an insulated conductor as earth) £1
IP65 Enclosure GR17020 https://cpc.farnell.com/ce-tek/gr17020/abs-enclosure-240x190x95mm-ip65/dp/EN84549?st=ip65%20abs%20enclosures £15
IP68 Cable Glands
x  2
  https://uk.rs-online.com/web/p/cable-glands/8829941/ £1
4w extension cable   https://cpc.farnell.com/brennenstuhl/1150403/4-way-switched-extension-lead/dp/PL03184?ost=pl03184 £5
Warning Sticker   e-bay £2
Sundries   Glue Gun, Cable ties, Push on Terminals, Earth Sleeve -
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