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The search for noise...

Mark_WS7MMark_WS7M Member ✭✭
When I first got back into Radio (1.5 years ago) 20 meters, my favorite band looked pretty cool.  Now it basically sucks (see the attached pic).

I have not had the time to search and seek for this but it drives me crazy looking at this noise.  I will need to find some time to try and ferret it out.  

Unfortunately, since starting a new job and having family issues I don't have the time I used to have. So hints and ideas would be very helpful.

Here is my plan so far:

1) Put my Flex on battery.  
2) Direct wire my laptop fo the flex
3) **** the power to the house and see if the signals still exist
4) Re-power the house but **** each circuit
5) Enable each circuit and try to determine which one adds the noise

Obviously steps 4, & 5 are not worth doing if the noise still persists after step 3.

Anyway I like 20, I hate that I have this killer noise right at 030 and 076 or so.  Two of my favorite hangouts.image


  • Mike va3mwMike va3mw Member ✭✭
    edited February 2018
    This will give you a good start. http://www.yccc.org/Articles/W1HIS/CommonModeChokesW1HIS2006Apr06.pdf Mike va3mw
  • edited May 16
  • edited September 2016
    I guess I'm luck.  This is a dead band with a 20M vertical attached.
  • edited March 2017
    Hi Mark,
    These signals are real and not from the power line. I get them here in the gold country occasionally, but they are really bad at My San Diego location. I have a 6300 on a sail boat so it is always running on battery with no ground loops or connection to the power lines. I also hear them on my FT-817 on battery power. I've tried to DF them with the FT-817 in SD and they seem to come from the directions of airports nearby. In SD they are even worse on 80 meters. I also have a Navy electronics lab nearby, on Point Loma, as you might have in your area. I hear them on 20 meters from my foot hills location and they look exactly like yours when 20 is closing down to the east and picking up to the west.
    I also hear them on my IC-7800 and my Collins receivers here in the foot hills so I doubt they are artifacts in the Flex equipment or any common mode problem.
    Mike W6MVM
  • edited September 2016
    In addition, all of my antennas have common mode baluns in them.
  • K5CGK5CG Danny Member ✭✭
    edited June 23
    That's so funny, I was just asking you about that SPE amp, and here we were doing exactly the same thing at the same time.

    I found out that I have some background noise being contributed by a switching power supply, very minor, but I am going to switch to an analog supply anyway.

    In addition, I have a Daiwa CN-801 cross needle power/SWR meter that was allowing RF into the receiver with nothing but a 6ft peice of RG-8X between the rig and the meter and 100 feet of unterminated RG-8X on the output of the meter. I took the meter out of the line and some of the noises went away.

    I was pleased to learn that my TP-Link AV2100 PowerLine Ethernet Adapters nor my laptop were contributing to the QRM.

    The power supply for the laptop makes some noise.

    Then I went through the breaker dance at the main panel and found that I could not get rid of any of the rest - still on the unterminated coax. This one birdie I'm seeing is coming from somewhere but no idea where just yet. I need to get the laptop off of WiFi when doing this so that when I **** my Ubiquity AP (on PoE) I can still see the radio on the LAN. I'll get my 100ft length of CAT5 so I can keep the laptop with me at the breaker panel.

  • Mark_WS7MMark_WS7M Member ✭✭
    edited September 2016

    That is a great but scary article!  That must be thousands of dollars worth of chokes!!!  :-)
  • Mike va3mwMike va3mw Member ✭✭
    edited September 2016
    It isn't that bad. I bought a bunch in bulk and now I am a choke fan. They solve so many problems, not just noise. The quieter you are, the more you can hear. Mike va3mw
  • edited September 2016
    Here's what I've tried to get rid of them in San Diego. I've tried to trace them with my FT-817 and a loop antenna. They aren't coming form any source nearby, such as a an inverter, TV or local source. I would have spotted it with this DF rig.
    I purchased an MFJ common mode noise rejection device and placed it in series with the antenna tuner. I don't remember the exact model number. I hooked it up with the built in antenna and with a long wire external antenna. I could see the signals in both antenna channels but they would not null. Several other noise signals did null but these signals did not null. If you listen to them they have a strange modulation to them. This I found totally confusing. As you ca see I've been fighting this problem for some time. I also have an IC 706MK2D as a backup transceiver and it also picks these signals up. 
    I sometimes have to use a remote internet receiver to hear my friends even though they can hear me.
    If anyone has an idea about this Let me Know.
    Regards, Mike W6MVM
  • Wayne VK4ACNWayne VK4ACN Member ✭✭
    edited March 2019
    Are they from solar panels or inverters?  I have spikes mainly on 20m and above that seem to not be there at night, so guessing solar.  Everyone in the area except me seems to have them on their roof
  • edited September 2016
    I thought of that since they are common on boats, but I could not spot them on the DF. I tried mine on and off but did not notice any difference. I run inverters all the time but did not notice a difference when I turned them off. I've checked all the obvious sources, LED lights, inverters, battery chargers and such to no effect.
  • Steve G1XOWSteve G1XOW Member
    edited September 2016
    A vertical is deaf compared to a 3 element yagi. I know from first hand experience, I can swing the beam and easily peak noise sources such as my Daughters xBox, next doors caravan battery charger etc. On a simple vertical there is not enough gain to reveal the problems that are out there.
  • Steve G1XOWSteve G1XOW Member
    edited May 16

    These are 90% switchmode PSUs, pretty stables ones by all accounts. May of the nastier one will wobble around +/- 20kHz.

    The prime suspects are: mobile phone chargers (plugged in but not charging is often worse), TVs (even on standby), any kind of wireless house phone charger/base unit.

    Your sigs look very very similar to my wifes bed-side cell phone charger.

  • Ross - K9COXRoss - K9COX Member ✭✭
    edited June 2017
    Terminate all neighbors.
  • KY6LA_HowardKY6LA_Howard La Jolla, CA. Paris and Sablet FranceMember ✭✭✭
    edited September 2016
    @Michael I am back in La Jolla first week in October. We can triangulate the noise
  • 9k2od9k2od Member
    edited September 2016
    just zoooom in pandapters and thos signals will go away ....
  • edited September 2016
    Hi, thanks for the help. I'll be north till after Pacificon. Back in SD then.
  • George Molnar, KF2TGeorge Molnar, KF2T Member ✭✭✭
    edited February 2019
    Good luck - noise mitigation can easily become a long-term crusade. Power supplies, routers, plasmas, bad grounds, RF-leaky "shielded" cabinets. Chokes will help, but "real" signals need to be addressed at their sources. Solar can be a killer. Two homes in my area, each about 3-4 blocks away, light up 6 meters when the sun is shining. Makes it tough on certain headings.
  • edited December 2016

    Danny, why not use a charged UPS for your AP while you test.

    Jeff, N3VE

  • K5CGK5CG Danny Member ✭✭
    edited December 2016
    I could but I have a car battery already fitted with Anderson PowerPoles so I'm good. I just hadn't gotten that far down the rabbit hole.

    Thank you, 73

  • Ken - NM9PKen - NM9P Member ✭✭
    edited December 2016
    Some UPS's also generate RF hash since they are essentially switching power supplies in reverse...

  • Michael - N5TGLMichael - N5TGL Member ✭✭
    edited October 2016
    I've made quite a few of those big huge chokes and they do work well.  Thanks for posting that article link, Michael, I had lost track of it.

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