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Low RFI wall warts?

I'm slowly working down the noise floor that is bothersome in the lower bands.  I've made some decent progress with robust grounding of all my equipment (good for a dB or so) and putting chokes in both ends of my PC-6500 Ethernet cable (a BIG help, it was NOISY).  Now I'm told that my many ham shack wall warts (most for USB ports) may be a noise source.  While they are small, they are often switching power supplies and potentially noisy.  I'd like to replace them. 
Does anyone have recommendations for a quiet (linear?) 5V power supply with multiple USB ports?
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Answers

  • Stephen Hawkins NG0GStephen Hawkins NG0G Member ✭✭
    edited July 2018
    Me too.  I am discovering noise sources everywhere.   Among the worst were two brand new Chamberlin garage door openers.   I need to find a inexpensive source for those snap on chokes, as with two, eight port switches I have a lot of cat5.  
  • Mike-VA3MWMike-VA3MW FlexRadio Employee, Community Manager admin
    edited November 2019
    This document is my bible regarding chokes. I highly recommend every one take a look at it. I've spent hundreds on mix 43 chokes and have been very pleased with the results and how I can hear so much better. http://www.yccc.org/Articles/W1HIS/CommonModeChokesW1HIS2006Apr06.pdfMike
  • Larry _ W8LLLLarry _ W8LLL Member ✭✭
    edited March 2018
    https://www.mouser.com/

    These are Mouser part numbers for 31 mix snap on chokes, other 

    mixes available as well. Pricing improves as your quantity 

    purchaced goes up.

    623-0431167281  Fits  LMR-240 10.15 mm ID
    623-0431164181  Fits  LMR-400 13.05 mm ID
    623-0431173551  Fits  LMR-600 18.8 mm ID
  • Alan CAlan C Member ✭✭
    edited March 2018
    Michael - are you sure that is the correct link? Couldn't find any choke article...thx
  • edited May 2019
    >"Me too.  I am discovering noise sources everywhere.  Among the worst were two brand new Chamberlin garage door openers."

    The latest Chamberlain models are strong RFI/EMI radiators. At my home QTH, I use open feeders located about 20 ft. away from the opener.

    The attached photo shows the fix -- as ridiculous as it looks.  To get ample turns, wires were extended and include the safety photo-sensor wires.    A single #31 toroid is used with several choking turns -- but that wasn't enough.  Also seen in the photo are Sprague low-ESR "Orange Drop" bypass caps.  That took care of it. 

    It's insane the extent to which we need to quiet down commercially-made digital devices these days.  Hunting down RFI from new home devices and appliances is always a constant battle here. 

    Wall warts: Thank God Jameco still sells a large selection of linear wall warts.  They have both regulated and non-regulated types.  I've ordered many over the years as replacements to the junk that's normally supplied with digital devices. 

    Paul, W9AC


       image
  • edited March 2018
    I think this may have been what he meant for the link.http://www.pi4vli.nl/download/Bijlage_Deltaloep_April_2016_RFI_Ham.pdf
  • Alan CAlan C Member ✭✭
    edited March 2018
    Got it. thx Larry...
  • Mark_WS7MMark_WS7M Member ✭✭
    edited March 2018
    I have personally simply tried to remove these by replacing them with either 12V or 5V products that I could power from my main 12V or a linear 5V supply.
  • John - K3MAJohn - K3MA Member ✭✭
    edited March 2018
    Good source of chokes and other grounding stuff here.
    http://www.kf7p.com/KF7P/Products.html

    John K3MA

  • Steve - K6SRSSteve - K6SRS Member
    edited December 2019
    Recommendation for a 5v linear power supply?
  • Kevin N9JKPKevin N9JKP Member ✭✭
    edited March 2018
    I too would like to find a 5vdc linear supply.  I have gott rid of all my other wall warts and would like to replace the 5vdc ones I still have left.
  • Ted  VE3TRQTed VE3TRQ Member ✭✭
    edited March 2018
    Looks nice, but not a linear PSU - still a switcher, which is OK if it is proven to be quiet. Of course that's often a crapshoot.
  • Mike-VA3MWMike-VA3MW FlexRadio Employee, Community Manager admin
    edited March 2018
  • Clay N9IOClay N9IO Clay N9IO Member ✭✭
    edited August 2019
    If you can find them at a decent price a nice 12v to 5v dc-dc converter module is made by TDK Lambda.

    Also, pending on your applications current requirement you could always resort to a 5volt regulator with an output filter cap. TO-3 case regulator will handle 1 1/2 amps at 5vdc feed it from your 12 volt supply.
    aka 7805 regulator. Just add solder.
  • Stephen Hawkins NG0GStephen Hawkins NG0G Member ✭✭
    edited March 2018
    I'll be happy with ridiculous if my 160m noise level goes down.  I have the torrid, what value were the caps an how did you connect them?  From each of the 4 terminals to ground?  If so what did you use as ground?  I can't tell from the photo how things are connected.  Info please.

  • Stephen Hawkins NG0GStephen Hawkins NG0G Member ✭✭
    edited March 2018
    I have replaced all my wallwarts with a long cable intesperesed with toroids, and lot of little short pigtails, all ending in the same plug the walwarts had.  The cable was powered by an Astron RS-20A, old fashion, non-switching, plain vanilla, QUIET, power supply.  A true pain in the **** soldering a heavier gauge wire on to all those plugs meant for little tiny wires.   I should have purchased stock in companies that make solder, and shrink tubing.  My Weller soldering station actually let out an audible sigh when I was done.  NSFW  A lot of swearing was involved.
  • Steve - K6SRSSteve - K6SRS Member
    edited May 2019
    All the USB chargers seem to be current controlled or limited to numbers like 1 amp or 2.1 amps.  I'm wondering - is there is a risk to different devices when all the outlets hooked to a 20 amp source?  Don't want to fry anything.
  • edited March 2018
    Right, the Orange Drops are connected from the four terminals to a chassis ground **** at the top of the unit - which of course relies only on the AC third-conductor ground wire.  Notice I used 3M Scotchlok IDC splicing connectors to join-up some of the existing opener wiring to the toroid.  

    The Sprague Orange Drops were on-hand.  They are 0.01 uF and physically much larger than necessary because they're rated for 630 VDC.  Again, I had a large stock of them but you can get by with a much lower voltage rating.    Ugly it is, but it's effective. 

    Paul, W9AC

  • Stephen Hawkins NG0GStephen Hawkins NG0G Member ✭✭
    edited March 2018
    Thanks.  I had a box full of .01 here that did not help much.  I suspect I did not wind enough turns through the toroid.  I'l lengthen them and try again.  The base of my 160m Inverted L is about 18 feet from the closest opener and my S meter reads 20 to 30 over S9 in the day time.  I have been getting by the last month by turning off power to the garage at night.  The night time temps were way below zero so it didn't hurt the stuff stored in the upright freezer in the garage.  Now that spring is peeking it's head over the horizon I can't do that anymore and need to get it fixed.  My calls to Chamberlin were a waste of time.  "Gee we never heard any complaints before so our openers must not be making the noise in your radio"   Arrrrrgh!  Thanks for the info, I'm glad to know it can be fixed.

  • Steve - K6SRSSteve - K6SRS Member
    edited March 2018
    Just pulled the power from my Sears Craftsman garage door opener.  It made no difference to the noise floor on 160 or 80, currently sitting around S4-5.  Too bad.  Was hoping for a quick fix.

    Have also unplugged most of the wall warts near the ham shack and antenna without impact.  Where is Sherlock Homes when we need him?

  • Bill -VA3WTBBill -VA3WTB Member ✭✭✭
    edited March 2018
    S4 or 5 is really not bad. Remember you will see an S3 with no antenna connected.
  • Steve - K6SRSSteve - K6SRS Member
    edited March 2018
    Not here.   See S0 switched to a dummy load or with antenna disconnected.
  • Bill -VA3WTBBill -VA3WTB Member ✭✭✭
    edited March 2018
    Interesting, the 6000 radios are designed to show an S3 with out an antenna.
  • Steve - K6SRSSteve - K6SRS Member
    edited March 2018
    Ahh.  You are correct.  S0 is what shows using my ICOM 7300.  Switching to the 6500 does indeed get me an S3 without an antenna or into a dummy load.  Interesting. 
    Not grasping the logic behind that.
  • Bill -VA3WTBBill -VA3WTB Member ✭✭✭
    edited March 2018
    In a radio there is always  RF around. In SSDR the receiver gets RF from the bins in the bandpass, so even without an antenna the bins are still active and produce a tiny amount of RF.  This is a very simple way of saying it.
    If you look around there are lots of discussion on this and Steve at Flex explains this in better detail. If your so interested.
  • KY6LA_HowardKY6LA_Howard La Jolla, CA. Paris and Sablet FranceMember ✭✭✭
    edited March 2018

    The bins DO NOT GENERATE RF   they are a mathematical construct to explain how SDR's receive a signal ;

    Background RF is always present - unless you have a perfect Faraday cage around the radio.    The 7300 does Not display the true environment but only a relative and basically meaningless approximation of the signal to background   The Flex displays what it actually hears

    https://d2r1vs3d9006ap.cloudfront.net/s3_images/935425/S-MeterGraph.jpg?1375457399 

  • edited March 2018
    Can you let us know what the noise level was before and after this fix? This is one thing I have never done (unplug it and see if it make any difference). One thing I have found is the shack laptop dell power supply and very noisy but unplugging it doesn't seem to have any effect on the radios noise level.
  • Clay N9IOClay N9IO Clay N9IO Member ✭✭
    edited March 2018
    Earlier in this thread Paul W9AC said that Jameco has a large assortment of linear wall wart supplies available.
  • Steve - K6SRSSteve - K6SRS Member
    edited March 2018
    According to the graph I'm between rural and quiet rural, about correct for my location.  So the QRM is just what it is these days?  Too bad.  I remember good old days when quiet was quiet.

    Reading S3 into a dummy load clearly is not anything like an accurate measurement of what is really coming in the antenna.  Seem like my 7300, although less smart, provides a more accurate representation of the antenna noise.
     

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