Clean Up Your Shack – 2019

The online follow-up to my talk for the 2019 RSGB Convention.

3 chokes

What’s new since 2015

  • Choke Chart and RadCom Plus article by Steve Hunt G3TXQ (SK)see separate blog entry below
  • Revised Choke Cookbook by Jim Brown K9YC
  • Large Fair-Rite #31 core
    These are a game changer!  
    See ordering details below.

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  • Constant changes in the prices of ferrite cores (but still the same Best Buy supplier)
  • Updated Whole-Shack Mains Filter

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Downloads

  • Extended slide pack (PowerPoint) includes more slides showing how to build the updated Whole-Shack Mains Filter.
  • View ‘Clean Up Your Shack 2015’ (YouTube) for more detailed background.
  • Slides from my 2010 talk about chokes and baluns  to drill deeper into that subject.
  • The two mains earth (green/yellow) wires are connected together at the earth tag on the filter. (Sorry, I can’t add a better photograph yet – the filter is away at the radio club, in a building under lockdown.)

Fair-Rite 0431177081 snap-on core

Not cheap, but well worth it. If RF noise threatens to take your hobby away, then surely it’s worth something to get it back?

  • Manufacturer’s data  Ignore the photograph – this biggest bead doesn’t look like that.
  • Current Best Buy supplier – and always near the top of the list –  is www.mouser.co.uk
    Again, ignore the photograph, trust the part number.
    Notice the big price break at quantity 10. This makes an ideal club purchase.
    UK prices are in GB£ but do not include VAT. However, that is all you have to pay. Three-day FedEx shipping from the USA is streamlined and free for orders over £50+VAT.

Parts list for the Whole-Shack Mains Filter

  • Packaged 15A or 16A mains filter, single phase, 250VAC rated.
    Within 2 days of publication, the Roxburgh RES5-F15 filter from Farnell was sold out! The specific type of mains filter is not critical, so instead let’s try the Schaffner FN2030-16-06 (also from Farnell, but many more in stock).
  • Large Fair-Rite core 0431177081: Mouser (see above) or Farnell
  • Qty 2, Fair-Rite oval core 2643167851: Mouser or Farnell
  • Plastic box CE-TEK GR17012 to fit the above parts: CPC  EN84544
  • Qty 2, plastic cable glands, 5-10mm size: CPC CBBR7352
  • At least 3m of 3-core 2.5mm² mains flex, 90ºC rated: eBay, eg here
  • 13A socket strips to meet your requirements
  • 13A plugThe maximum total current supplied to all sockets is 13A, limited by this plug.

55 thoughts on “Clean Up Your Shack – 2019

  1. Peter

    Good day

    I attended the RSGB Convention and was pleased to be able to see your presentation on cleaning up the shack. I learnt a lot, and will be implementing many of your suggestions.

    Recently I had decided to renew my coax feeders, and bought some Messi and Paolini Ultraflex 7 to do this with. From the data sheet, the minimum advised curvature in multiple bends is 68mm, giving coax loop diameters of 136mm, which might be acceptable at the antenna feed-point, but would be somewhat cumbersome at the point where the feeder leaves the radio. I intend to use 2 stacked FT240-31 toroids for the choke formers. I wondered therefore if RG58 which can be encouraged to a smaller diameter would be suitable for the choke construction, or perhaps you would suggest I should invest in some of the thin Teflon coax. In either case, the choke for use at the radio end would have to have connectors at each end in order to ‘splice’ it into the feed line. I have always tried to avoid unnecessary connectors in the feedline as I understood they would be sources of potential problems. Is the benefit likely to outweigh any issues that an additional 2 connectors in the feedline might provoke? (Maximum feedline length is 45m)

    I usually work at 10W, with ocasional forays to 100w, and only rarely 400W. My location is semi-rural, and although I am not as plagued with nose as some of the recent correspondents to RadCom have indicated, anything to help seems to be a good idea. As I am making a change to my feeders, I would like to do the job just once, but properly.

    Thank you for your talk, and the links to the other aspects of the topic.

    73
    Peter
    M0RYB

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    1. GM3SEK Post author

      Hello Peter

      Glad that you enjoyed the talk, and I’m sorry it wasn’t possible to be there in person.

      At the power levels you normally use, I would be inclined to wind the chokes with RG58. It will allow you to wind more compact chokes and will also handle 400W for occasional use. Don’t worry too much about connectors – good connectors, correctly fitted and well waterproofed, should never be a problem.

      73 from Ian GM3SEK

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  2. Alison

    Hi, I’m presently buying the components to make your mains filter, I understand why you’ve used a 31 and a pair 43’s however what about the lower frequencies? For complete coverage surely you should have a mix 75 / J in there somewhere as well? (I’m an avid LW / MW listener as well as the Ham bands). What do you think about half a dozen or so turns around a type 75 ring (or two of them, stacked) immediately after the twin 43’s? Thanks, Ali.

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    1. GM3SEK Post author

      Hello Ali

      Thanks for your comments. The filter that I showed was optimized for 1.8-30MHz, and I have not considered any lower frequencies. However, from the mention of #75 mix I guess that you have already read K9YC’s paper on ‘Chokes and Isolation Transformers For Receiving Antennas’ [1], where Jim shows some common-mode chokes for MF antenna feedlines that can easily be wound on small #75 toroids using twisted pairs from CAT5 cable.

      [1] http://k9yc.com/RXChokesTransformers.pdf

      The difficulty for a MF mains choke is the much larger wire diameter (three heavy wires twisted together) and the much smaller size of the available #75 cores – particularly the internal diameter through which the multiple turns of twisted wires must pass. On the positive side, extremely high choking impedances are probably not necessary for a mains choke because the prevailing system impedance is quite low. A possible candidate may be the 0475176451 snap-on core: if you reduce the size of the mains wire to 1.5mm^2 it may be possible to fit 4 or 5 turns through, which would give a useful choking impedance below 1MHz.

      Obviously haven’t tried this myself but would be interested in any results.

      73 from Ian GM3SEK

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  3. Bernard

    Hello Ian
    Thanks for all the work you do make our hobby more rewarding. This may be a blindingly obvious question but where does the earth (green/yellow) wire go after it exits the large snap on? I can see that the live and neutral from the snap-on go to the commercial mains filter and also that all three wires from the mains go to the commercial filter. Many thanks, Bernard.

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    1. GM3SEK Post author

      Hello Bernard,
      The earth wire from the unfiltered mains input and the earth wire going to the RF chokes both connect to the “E” tag on the metal body of the mains filter.

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    1. Bernard

      Having now built the filter exactly as described I can report a huge improvement in noise levels (S7/8 to S3 on 40m and 80m). These lower bands were off limits to me in the past as far as SSB went and now they’re not. Couldn’t be happier! Many thanks Ian for the work you have put in to offer RFI/EMC solutions to the Amateur Radio community.

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  4. Mike Naylor

    Ian,

    I wonder if it is acceptable to install the filters as part of a permanent installation? I am reluctant to ask my electrician to do this unless there is a precedent.. The reason for doing this is that more sockets could be protected by one filter.

    73 Mike G4CDF

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    1. GM3SEK Post author

      Mike,

      I do not know the regulatory situation for a permanent installation, but it’s sure to be more restrictive than for a 13A extension.

      If you only need more sockets than the 6-way board shown in the photographs, double-row boards are available up to 10 ways – always provided that the total load does not exceed 13A. However, there are also several other factors that limit the current capacity of this mains filter to 13A, including the 3-core flex, the number of turns that can be passed through the centre of the ferrite cores, and the current rating of the packaged mains filter.

      Sorry that I can’t be more helpful.

      73 from Ian GM3SEK

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      1. Mike G4CDF

        Ian, many thanks. I will follow your proven design as it is more flexible.
        I have also seen your slides on VHF/UHF baluns. Apart form the baluns at the antennas do you recommend any filters on the rigs or supplies?

        73 Mike G4CDF

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      2. GM3SEK Post author

        Additional filters on commercial rigs should not normally be needed. ALL switchmode power supplies need filters on both input and output, but that topic is well covered elsewhere.

        73 from Ian GM3SEK

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  5. davek0974

    Hi, i’ll be building the filter and have the parts on the way, thanks for all the research work here.

    I’ll also be bonding my equipment as outlined in the clean-up-your-shack video, but i’m unsure if the bonding plate/braid should be connected to the filtered mains earth point or not??

    Thanks
    Dave (awaiting callsign)

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  6. Pingback: Clean Up The Shack – Part 1 – M6RUG

  7. GM3SEK Post author

    Yes, the mains earth connection on the shack side of the filter should be connected to the equipment bonding strip. That was mentioned in the 2015 talk, but I should have included it in the 2019 update as well.

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  8. Pingback: Clean up your shack – Part 2 – M6RUG

  9. John

    Hi Ian
    Well thanks for all the info. I have just placed the order with Farrnell and CPC so hope to have the filter all built by weekend. I also ordered up the kit to build the CM Chokes as well. I dropped an email to your old blog posts if you can check thanks

    John

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  10. Dave M6RUG

    Hi Ian

    Quite simply, thank you!

    Your filter design is working a treat on 20m and above with 3-4 S points of noise gone! 40/30 just 1 S point.

    I did not manage to twist the wires together successfully and still get 7 turns so ended up with them flat.

    Regards

    Dave (M6RUG

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  11. John

    Hi Ian,

    Looking forward to building one of these. Any differences when dealing with 110VAC as opposed to 220?

    73,

    K5JBT

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    1. GM3SEK Post author

      Hi John,

      Two differences that I can think of, compared with 220/230V:

      1. All AC supply currents will be multiplied by about 2. The practical limitation will be the current/temperature ratings of the twisted wires that you use for winding the chokes.

      2. Also be careful about the ratings of the packaged mains filter (sorry, I have no experience about 110V AC).

      73 from Ian GM3SEK

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  12. Bill

    Dear Peter,
    Regarding the Cost-effective Ferrite Chokes and Baluns (May 2010) article which is a similar topic. I was going to build these 3 frequency designs and noticd a comment that the 3 frequnecy design can be built as one unit (saving connectors) A silly question but is there a correct order that the 3 frequency designs should be built as one unit?

    I have had great success with original 3 stage mains filter and built a couple of years ago the updated design with large core.. Noted you have now updated the build list to included a bigger box and changes due to availability of components.

    Still use both mains filters so thanks for the designs.
    Regards,
    Bill.

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  13. Pano Kato

    Hello i want to ask some thimgs, the filter you use (Packaged 15A or 16A mains filter, single phase, 250VAC rated.) is it enough for the hole shack? PC ,rig, and other staff (only 16A)?
    Aslo please could you explainto me both (earth s) goes to the same spot (earth spot) on the filter ? Thank you very much ! 73

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    1. GM3SEK Post author

      For a typical “100W RF” station (no power amplifier), 13-16A should be more than enough current capability.

      If you use a large power amp, that may increase the mains current beyond the capability of the board.of the board. (You have to measure the current yourself – I can’t tell you what it will be.) A power amp will require its own RF choke on all three wires of the mains connection.

      The packaged mains filter only has connections for Line and Neutral. It does not filter the earth wire, so both earth wires connect to the same point on the metal case. (I would like to take a better photograph, but the filter is under lockdown at the radio club.)

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      1. GM3SEK Post author

        That is exactly what I already use, Bern – but thanks for the kind offer of course. Sorry that I can’t provide a better photograph at the moment.

        73 from Ian GM3SEK

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  14. Pingback: The ongoing quest to reduce QRM – Mains Filter #2 | M7ALU Site

  15. alanknipmeyercouk

    Added the updated filter to my shack – Thanks to Bern/G8KVM for the link. Its proving really valuable – many thanks for all your work – this filter is brilliant.

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      1. alanknipmeyercouk

        thank you – i was wondering with the filter, is there any tests/visualisations i can do with it by attaching it to an oscilloscope ? I’m all new (only licence in december) and eager to use the equipment and build up my knowledge of how to use it with an amature radio station. Scope is a rigol ds1202z-e

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      2. GM3SEK Post author

        Hi Alan,
        Since you only recently got your licence (and from “all new” I’m guessing you do not have any other electronics background) I strongly suggest you DO NOT try to make any measurements with your oscilloscope that involve direct connections with the mains! This can be dangerous – both to yourself and to the ‘scope.
        Even experienced electronics technicians often do silly things when making measurements on the mains using a ‘scope. In particular, if anyone suggests disconnecting the earth wire at the mains plug, don’t listen to them!
        Sorry that I can’t be more positive or helpful, but until you have a lot more experience, the risks are far greater than the benefits.
        73 from Ian GM3SEK

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  16. Bernard Rhead

    Thanks again to you Ian. I was listening on 80 and 40m last night and until I built and installed the filter these bands were completely unusable. It’s really rewarding when something works so well.

    Bern

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  17. Ross

    Hi,

    Thanks for your efforts with regards to the mains filter and for sharing it with us all !

    Am I right in saying that a separate single core earth cable should be attached at the the mains earth connector block on the shack side of the filter and then ran to the grounding nut on the back of the transceiver ?
    Sorry if I am asking a silly question here !

    73

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    1. GM3SEK Post author

      Hi Ross,
      Yes, there should be a connection – but there are better ways to do this than a single wire. See the last 10 minutes of my 2015 presentation which talk about ground bonding using a broad metal strap cross the back of the operating bench.
      73 from Ian GM3SEK

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  18. Ian MM0GYX

    Hello Ian, I have just finished watching the presentation. The plan is to construct the mains filter and work on the bonding, chokes etc. I do moan about a noisy QTH, so need to get stuck in to this.
    Towards the end of the presentation you talk about power supplies needing to not have the ground connected at the negative terminal, mine is, so opened it, crikey it’s not so accessible. However, this PSU is a switch mode unit, presumably it would be better to go linear?

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    1. GM3SEK Post author

      Hello Ian,
      Are you sure that the negative lead of the 12V output is connected to mains earth? (Meter reads zero-ohms between the negative lead and the case of the PSU, and between case and mains earth?)

      A linear PSU is probably better anyway, but do confirm that you’re not buying another PSU with the same problem!

      73 from Ian GM3SEK

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      Reply
  19. Ian MM0GYX

    Hi Ian,

    Thanks for replying. Zero ohms between the negative connection pillar and chassis or with a kettle lead plugged in the earth pin, chassis and earth pin obviously zero ohms too. That is with everything unplugged from the PSU. So, certainly seems to be connected inside, I’d need to dismantle this quite a bit to get at the connection. It’s several years old and was bought used, probably time to replace it soon anyway.

    73,

    Ian MM0GYX

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  20. Michel Frias

    I need help. I have this noise in my Icom 7300. I using the PS Astron RS-35A with one filter inside that I install yesterday but the noise persist. I have also the ugly choke with 10 ft in 4” pvc. I can’t to kill this noise in 15 Mhz to 30 Mhz. I using the Sirio 827 10-11M vertical antenna and the coaxial RG8x TRAM TRAMFLEX 112 ft…. https://www.youtube.com/watch?v=o3SU-1aN-Vw&t=2s

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    1. GM3SEK Post author

      Michel, it is very difficult to help you from this long distance.

      The best way forward that I can recommend is to buy *2 or more* of the large Fair-Rite #31 snap-on beads and try the effect of making chokes of 3-5 turns at various places on your system. The first place to start is at the feed-point of your vertical antenna. If a choke makes some improvement, then leave it there and continue with another bead in other places.

      Sorry, I know that those beads are very expensive. They are expensive everywhere outside of the USA but there is no alternative.

      73 from Ian GM3SEK

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  21. Tom Wylie GM4FDM

    I have built Ian’s mains filter as described and am happy to report a reduction in noise which makes 17m now usable. I still have noise coming in on the antenna and have ordered even more ferrites from Qubits (I dont know what the guy must think of me as recently have been one of his best customers.) I found the filter very straightforward to build with the components identified by Ian

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  22. Richard G3OQT

    Hi Ian

    I am in progress of building your mains filter. I also want to fit chokes on all the incoming antenna cables. In the interest of neatness I would prefer to put all four of them in one plastic box. Two of them are tx antennas and the other two are a Beverage and a remote rx mag loop. If all ferrites were in one box would there be an unacceptable level of cross coupling between the high power tx ones and the rx ones which go straight to the separate rx input on the radio?

    PS do you remember the Romford club in the 60s?

    73 RIchard G3OQT

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    1. GM3SEK Post author

      Hi Richard – great to hear from you, and I hope you’re well in these strange times. I do indeed remember the Romford club (but somehow the mornings-after are a lot more hazy).

      There should not be much coupling between different chokes in the same enclosure. Good ferrite chokes will keep the common-mode currents very low, and any residual external fields will be confined very close to the separate cores. But having said that, why risk it? If you use one box for the TX chokes and a separate one for the RX chokes, that will reduce the coupling even further and could open up even more options to try, like in-band listen-through (which immediately brings back LUI-Dick’s tales of full duplex CW in the RAF).

      73 from Ian GM3SEK

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  23. H.Buckenham

    Hello Ian and Richard,
    Ian, I have looked at your projects over the years and have found them extremely interesting.
    I have done a lot of ferrite work myself especially with HF and VHF couplers and combiners.
    Like you and Richard, I have many fine memories of the RAFA club!
    73s,
    Howard, G3PGN.

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  24. Dave Gynn

    Hi Ian

    Built your Mains Choke and fitted a 13Amp switched socket into the box and really pleased with the result both aesthetically and practically. 80m looks a lot better now.
    Thanks very much
    Dave. G3SBP

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  25. Gopan

    Hi Ian,
    One more happy chap here. I have now less noise on 40 & 80. Thanks for sharing your knowledge !!!

    73 Gopan
    M0XUU / VU3HPF

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  26. Dave

    Hi Ian,
    thanks for the information here, very interesting. I’m in the process of building the mains filter and have, what is probably a bit of a dumb question, but as this is mains electricity we’re talking about i thought i’d check.
    I’ve got the Schaffner filter and just need to clarify the connections to it. The earth has 1 tag, and is unfiltered, so 2 connections are made there. But, which side do i connect to the plug end? I assume the ‘Load’ connects directly to where the 13A plug is connected in your photo and the ‘Line’ then feeds directly to the Fair-rite cores? Just thought i’d check
    cheers
    Dave
    M0IKT

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    1. Ian MM0GYX

      I’m interested in the answer too, I set mine up the other way around. Line to plug, radio equipment etc to load.

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    2. GM3SEK Post author

      Sorry Dave, I thought I had replied to this one, so thanks to Ian MM0GYX (who has the same question) for reminding me I hadn’t.

      I don’t think the way-around of the packaged mains filter is a major factor. Choosing to place the end with the earth tag closest to the RF choke was simply for convenience. It’s much easier to wind the RF chokes if all three wires are the same length.

      However, I would be very interested to learn of any cases where turning the filter around does make a difference. (You will recall that I haven’t laid eyes on the prototype since February, because the building that houses our radio club remains under lockdown.)

      73 from Ian GM3SEK

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