The search for noise...

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  • Question
  • Updated 3 years ago
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) Kill the power to the house and see if the signals still exist
4) Re-power the house but kill 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.
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Mark - WS7M

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Posted 3 years ago

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Mike va3mw

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This will give you a good start. http://www.yccc.org/Articles/W1HIS/Co...
Mike va3mw
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Mark - WS7M

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Yikes!

That is a great but scary article!  That must be thousands of dollars worth of chokes!!!  :-)
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Mike va3mw

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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
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Michael - N5TGL

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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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Andrew O'Brien

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Andrew O'Brien

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I guess I'm luck.  This is a dead band with a 20M vertical attached.
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Steven G1XOW

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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.
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Michael McGinty

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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
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Michael McGinty

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In addition, all of my antennas have common mode baluns in them.
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Michael McGinty

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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
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Danny K5CG

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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 kill 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.

Danny
(Edited)
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Jeffrey Kerber, N3VE

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

Jeff, N3VE

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Danny K5CG

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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
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Ken - NM9P

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Some UPS's also generate RF hash since they are essentially switching power supplies in reverse...
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Wayne VK4ACN

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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
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Michael McGinty

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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.
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KY6LA - Howard, Elmer

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@Michael

I am back in La Jolla first week in October. We can triangulate the noise
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Michael McGinty

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Hi, thanks for the help. I'll be north till after Pacificon. Back in SD then.
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Steven G1XOW

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Mark,

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.
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Ross - K9COX

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Terminate all neighbors.
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Osama

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just zoooom in pandapters and thos signals will go away ....
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George Molnar, KF2T, Elmer

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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.