Reducing interference in the shack

Ben from MBARS provided a useful link to a mains choke he has built recently based on the one in this blog: GM3SEK’s Technical Blog | Notes about current projects and topics, including followups to GM3SEK’s Amateur Radio Technical Notebook

I have several sources of interference to sort out, the main one being the bathroom lights which splatter VHF at S8!

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HI Mark

Your posting stirred me into action and I built two for each of the 13 amp filtered socket boxes for my shack. Now I am sure the mains to all equipment in the shack is well filtered. I already had three of the Large ferrites bought from Mouser in 2019. I got the boxes from Rapid and the Schaffner filters and elliptical ferrites from Mouser. I used a 13 amp switch sockets with a larger box. The ferrites wired together only just fitted across the width of the box (90mm). I have 15 mains powered devices plugged in in my shack, so I bought 2 X 10 way Surge protected boards and mounted them on the wall fed from the two filters. Previously I had an 8 way and 2 X 4 ways directly on the mains. I soldered to the filters rather than used crimps.

73 Phil G4OBK

Good job that @G4OBK Phil!
As you’ve mentioned not much room for manoeuvre in that enclosure!
Has it made any difference to your noise level?

I noted that the ICOM IC-7100 that I have recently swapped for an FDM Duo I wasn’t using comes with 2 x SO-239 connectors. The VHF/UHF one can be swapped for an N-Type without any soldering required, so I will do that as my down-feed from the X50N has an N-type connector. I have tried to standardize on N-Type where possible, it connects direct to the FT-857 for example. I plan on following Icom IC-7100 SO-239 to N-Type – M0UKD – Amateur Radio Blog instructions.

If it is to hand could you post a parts list @G4OBK for Mouser?
Thanks, Mark.

HI Mark

Cannot be sure the filters make any difference here as everything in the shack is well ferrited and well grounded to my external earth and ground system in the back garden so I have no severe interference problems apart from occasional static type interference from electrical applicances in people’s home seemingly coming in via the antennae. My next door neighbours fairly new central heating boiler radiates a 16.5 KHz spaced hetrodyne through the HF spectrum which the notch filter deals with if it drops on a station of interest. She is elderly and a good neighbour, she let me in to the house with the KX2 about 18 months ago and this proved that it was the Vailant Ecotec plus 418 central heating boiler that was to blame. Nothing can be done about it - as I am not the customer the firm ignore my emails.

Parts list here:
Mouser
Fair-Rite ferrite clamp on cores low & BB Freq 31 Mat (Bought Jan 2019)
Fair rite ferrite cable cores 43 Full flat cable core (2 needed per filter)
Schaffner power line line filters 16A fast-on (1 per filter)

Rapid Electronics
Hammond RL6465-F Flanged ABS wall mount instrument enclosure 150L X 100H X 90W - box width very tight - only just accomodates ferrite filters when wound.
Schneider Electric GGBL3010S LWM 1 gang 13A switched mains socket

Cable - domestic appliance sized 3 core mains cable - I had that in stock. Clip on ferrite just accommodates 7 twisted turns of that sized cable. Any thicker and you would struggle to get 7 turns through the middle.

Volt drop through filters off load is approx 1 volt when tested. 232V in 231V out.

73 Phil