Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: 59+20 noise every 66 KHz strongest on 80m  (Read 4764 times)
NO9E
Member

Posts: 382




Ignore
« on: February 11, 2012, 01:53:56 PM »

After coming from a  long trip I noticed a broadband noise that on 80m is 59 with additional 59+20db spurs every 66 Khz with some weaker spurs every 33 KHz. Around 3.2 MHz the noise is almost 59+20 continuous. The noise is wideband but much weaker spurs on 15m. My various directional antennas indicate different directions. An AM receiver shows strong but varying signals under power lines and the strongest next to cable outlet. Any idea?

Ignacy, NO9E

Logged
K2OWK
Member

Posts: 1037




Ignore
« Reply #1 on: February 11, 2012, 02:30:37 PM »

Hello, Need additional information. What type of power supply are you using. Is the RFI constant or does it go away at times.

73s
K2OWK
Logged
NO9E
Member

Posts: 382




Ignore
« Reply #2 on: February 11, 2012, 02:39:57 PM »

This noise is not from my house. I heard it under power lines walking quarter mile. However, regular line noise does not have 66 or 33 Khz spurs. The noise the the loudest next to a Charter TV cable, however, before the cable was very quiet. There is U-Verse around, but their noise was much weaker and < 8 MHz.
Logged
K2OWK
Member

Posts: 1037




Ignore
« Reply #3 on: February 11, 2012, 09:07:50 PM »

Hello again NO9E, I would call the power company involved with the power line in your location. They have the equipment to check the power line which seems to be the problem. I would also call Charter Cable and have them check there cable system. Tell them what you told me in this post and show them the problem you are having. Most companies will help you solve a noise problem, especially if it is caused by them.

Hope this helps,

73s

K2OWK
Logged
WX7G
Member

Posts: 5920




Ignore
« Reply #4 on: February 12, 2012, 08:44:40 AM »

That is noise peaks every 66 kHz tells us it is not power line arcing noise. Power line arcing noise occurs every 120 Hz and on a ham receiver will appear as broadband noise.

It is most likely switching power supply noise. Being that it is at such a low rate (33 and 66 kHz) is is a big switching power supply running at 33 kHz (that is low), possibly industrial. Do you have any industry in your area that could have such a power supply?

The first thing to do is to make sure 100% it is not from your house. Run your radio on a battery, turn OFF the AC power to your house and confirm that the noise is gone.
Logged
WB4BYQ
Member

Posts: 179




Ignore
« Reply #5 on: February 13, 2012, 06:04:11 AM »

this sounds like a switching power supply, one that is pulling enough ac current to make the rfi this loud on the radio.  maybe a battery charger, or something like this:
http://www.w0qe.com/RF_Interference/grow_light_electronic_ballasts.html

you will have to use a receiver with an attenuator and the rf gain to really locate the source.  cannot be sure of the source type until you find it.  i used the yeasu ft-897d on battery and the  5/8 meter ant to find the source.  drive around the area.  i have seen battery chargers make this type of rfi, ones that charge large batteries.

Richard
Logged
NO9E
Member

Posts: 382




Ignore
« Reply #6 on: February 13, 2012, 07:02:25 AM »

I walked around a few blocks with an AM receiver tuned to 80m and with S-meter. The noise is the strongest below power poles 3 poles up from my house and 3 poles down.  Much weaker or no this kind of noise besides. I was monitoring the noise at 3804 and the noise is much weaker at 3800 and 3808.

My 3 el vert array points to east for the noise. My 20m 2 el quad points to east AND west but the offending noise is mainly from 2 to 5 MHz.

The extreme poles that mark noise have a ground entrance of RG6.  There is Charter cable around but it never caused trouble. Not sure whether to call the power company or Charter. I have been wrong a few times before when asking for help so I am hesitant to call for help right away.

The noise stays the same when the house power is off. So definitely no house noise.
Logged
WB4BYQ
Member

Posts: 179




Ignore
« Reply #7 on: February 13, 2012, 08:20:42 AM »

the rfi is a conducted emission into the power system running up and down your street.  the rfi will also flow on the ground wire that is below the hot wires at the top of the pole.  the rfi will no flow past the transformer in the 7200 volt feeder lines, but will flow thru the ground system.
the ground system is ground for 60hz ac but not the 3.800 mhz rf.  try using a receiver with a attenuator and a variable rf gain control to vary the receivers level of reception. you should be able to find the pole that has the loudest rfi.  then if that pole feeds say three homes, then one of homes is problem.  i used the yeasu to find the exact home by walking up to the power meter on the side of the home using the rf gain very tight to were the strongest signal will be detected into sound.  i have walked up the driveway also and could tell which house has the loudest rfi.  you will most likely have to enlist the help from the ARRL Mike Gruber the EMI/RFI engineer to assist you in resolving this matter. 

be careful walking around.

richard
Logged
WB4BYQ
Member

Posts: 179




Ignore
« Reply #8 on: February 13, 2012, 08:40:02 AM »

i also purchased this receiver.  does alot and found lots of noise with this receiver.
all hf coverage
usb and lsb with bfo
variable attenuator
telescoping ant

good of doing rfi fox hunting.

richard

http://www.universal-radio.com/catalog/portable/0360.html
Logged
NO9E
Member

Posts: 382




Ignore
« Reply #9 on: February 13, 2012, 08:51:37 AM »

Excellent directions.

With Grundig G6 one can fold the telescopic antenna for an attenuation effect. The noise I am talking about shows full deflection with the telescopic antenna fully folded most of the time. 

The noise seems to be the strongest by my neighbor's house. However, my 3 el vert receive antenna indicate the opposite direction.  The power line ends 3 poles down the street but it continues for a mile going up. Still the noise continues only for 3 poles up. In the past, I suspected the neighbor while the actual culprit was something else. So I am playing safe.


Quote
the ground system is ground for 60hz ac but not the 3.800 mhz rf.  try using a receiver with a attenuator and a variable rf gain control to vary the receivers level of reception. you should be able to find the pole that has the loudest rfi.  then if that pole feeds say three homes, then one of homes is problem.  i used the yeasu to find the exact home by walking up to the power meter on the side of the home using the rf gain very tight to were the strongest signal will be detected into sound.
Logged
KJ7YY
Member

Posts: 13




Ignore
« Reply #10 on: February 21, 2012, 05:49:52 PM »

Your noise sounds very simular to the problem I had here.  After searching and having the power company torubleshooter come out it turned out to be an electric pet fence a couple of houses down the street.  A filter installed on the fence box solved the problem.
Good luck, John  KJ7YY
Logged
WX7G
Member

Posts: 5920




Ignore
« Reply #11 on: February 22, 2012, 03:28:48 AM »

I walked around a few blocks with an AM receiver tuned to 80m and with S-meter. The noise is the strongest below power poles 3 poles up from my house and 3 poles down.  Much weaker or no this kind of noise besides. I was monitoring the noise at 3804 and the noise is much weaker at 3800 and 3808.

My 3 el vert array points to east for the noise. My 20m 2 el quad points to east AND west but the offending noise is mainly from 2 to 5 MHz.

The extreme poles that mark noise have a ground entrance of RG6.  There is Charter cable around but it never caused trouble. Not sure whether to call the power company or Charter. I have been wrong a few times before when asking for help so I am hesitant to call for help right away.

The noise stays the same when the house power is off. So definitely no house noise.

Sounds like you've used up your three wishes with the power company. You might be on your own.

Can you apply clamp-on ferrite cores to the RG-6? You might need several, perhaps 10 of the cores sold by places such as DX Engineering.

Or, since the noise is below 5 MHz, give up operating 80 meters. What else can you do? The MFJ noise canceling box might help. I use that on 80 meters and for a single noise source it works well.
Logged
WD8KDG
Member

Posts: 45




Ignore
« Reply #12 on: February 22, 2012, 09:48:44 AM »

Power line noise can be found with a VHF receiver tuned around 130MHz or so. Your noise heard every 66KHz on 80 meters is most likely from a Part 15 device.

You could be chasing your tail. I've noticed some of these Part 15 devices will couple to the steel support cable which is used to hold up telephone & TV cable utilities. This steel support cable acts as a long wire antenna and spreads lots of joy to the neighborhood!

TV cable leakage would also be up in the VHF/UHF spectrum.

With that: Walk around the neighborhood and find a spot where the telephone/TV cable lines do NOT follow power lines. If the harmonics from the Part 15 device are found only under telephone/TV cable lines; you got a winner. Now walk some more around the neigborhood and if the portable SW receiver has a telescoping antenna, shorten the length as the signal get louder.

With a little luck the portable SW receiver will walk you to someone's front door.

Craig,
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!