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Author Topic: Noise level  (Read 2075 times)

Offline BDM

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Noise level
« on: October 08, 2012, 1728 UTC »
I made a short vid today around 1/pm EST of this noise. I put in the description of what you are seeing in the vid. Mind you, I've shut the house down electrically and it made absolutely no difference in my noise level anywhere I tested. Thoughts??

http://www.youtube.com/watch?v=M2g12FFIs6Q
Radios -- Perseus SDR // Icom IC-7410 // Tecsun PL-660 // Panasonic RF-5000A --Antennas-- Pixel Pro 1B loop - 82' fan-dipole at 40' - tuned MW/BCB 40" loop and 100' receive only dipole
-Brian--North of Detroit--MI-
1710/KHz the MW Pirate Clear Channel (not so much anymore "sigh")

Offline ChrisSmolinski

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Re: Noise level
« Reply #1 on: October 08, 2012, 1913 UTC »
I'm quoting your comments from the video page for clarity:

Quote
Watch this in higher resolution 480. Notice the difference when I switch between the Alpha DX-CC 80 - 10 meter fan dipole and Pixel active loop. The loop has a much lower noise floor. What is strange especially on both 80 and 40m and how the noise level peaks at the resonant points of the dipole. It's an obvious "speed bump". This was not an issue 7 months ago. Not sure what has changed. Match is right were I set it on those bands and has not been an issue such as when connection issues exist. Grounding makes no difference at all. The NB has no real effect either with the Perseus SDR or Icom IC-7410. It intensifies more so at night than day. Any thoughts or questions?

A few general observations, maybe related to your situation, maybe not:

My experience has been that loop antennas inherently have lower noise pickup than dipoles. To the point where I simply don't use dipoles any more. Period.

I'd expect higher noise pickup levels around the resonant frequencies of an antenna, simply because it is going to pick up more signal at those frequencies. You mention this was not the case previously, so indeed that brings up the question of "what has changed?".  I have a few stations that I use as references, generally a few MW stations and some semi local SW stations (like WWV, CHU, and CFRX 6070). I know how well they come in at various times of the day. Checking them lets me see if something strange is going in with either propagation (the SW stations) or my antenna (the MW stations, which are essentially immune to propagation, esp during the daytime).

I get much higher noise levels at night than during the daytime. This is because propagation to distant areas is better at night, so you are getting more signals from the various thunderstorms all around the world, the predominant source of the static we hear. Note I am speaking of 43 meters in particular, and lower frequencies in general.

If this is indeed just pickup of atmospheric static, then grounding should not make much of a difference, if any. You're picking up an actual signal (distant thunderstorms) not a local source of interference.
Chris Smolinski
Westminster, MD
eQSLs appreciated! csmolinski@blackcatsystems.com
NRD 545 / netSDR / AFE822x / AirSpy HF+ / KiwiSDR / 670 ft horizontal loop / 500 ft northeast beverage / 58 ft T2FD / 300 ft south beverage / 43m / 20m / 10m  dipoles / Crossed Parallel Loop

Offline BDM

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Re: Noise level
« Reply #2 on: October 08, 2012, 1936 UTC »
Thanks Chris. Yes it is all the time 24/7. It started about 7 months ago. I've put it off hoping it may go away, but not so. I know loops inherently reject electrical noise but what a difference. I remember there was a natural sight curve through the resonant portion of the antenna (expecting that), but it's like a speed bump when this ambient noise had showing up. Next on the list, bulldoze my neighbors property into the ground to eliminate any further noise...Just kidding :o
Radios -- Perseus SDR // Icom IC-7410 // Tecsun PL-660 // Panasonic RF-5000A --Antennas-- Pixel Pro 1B loop - 82' fan-dipole at 40' - tuned MW/BCB 40" loop and 100' receive only dipole
-Brian--North of Detroit--MI-
1710/KHz the MW Pirate Clear Channel (not so much anymore "sigh")

Offline BDM

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Re: Noise level
« Reply #3 on: October 08, 2012, 2144 UTC »
The more I listen to that, the more I'm thinking that is line noise. Maybe a call into my power company is in order...
Radios -- Perseus SDR // Icom IC-7410 // Tecsun PL-660 // Panasonic RF-5000A --Antennas-- Pixel Pro 1B loop - 82' fan-dipole at 40' - tuned MW/BCB 40" loop and 100' receive only dipole
-Brian--North of Detroit--MI-
1710/KHz the MW Pirate Clear Channel (not so much anymore "sigh")

Offline Northwest Radio

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Re: Noise level
« Reply #4 on: October 28, 2012, 0922 UTC »
This is mainly Power Grid noise. Here is what I would do.

Get an old, simple transistor AM radio and do some sniffing.
Walk your neighborhood and note noise on the radio. As you pass poles, give them a good solid kick and note any reactions. Write down pole ID numbers that have reactions.
Don't worry about poles more then 100  meters away.

Call the power company and ask to speak with their RFI tech. Let them know what you have learned. This will show them  you are serious. Power companies are not licensed broadcasters and most make big efforts to prevent such RFI. They can be fined for it. Be firm, but do not be threatening or rude, just yet.

If you live in the US, I can provide you with an FCC phone number/email that will help if they are slow to react. The FCC agent will contact them and light a fire under their backside.

Once they come out, they should report what they found and will fix it. I have had to do this more than once in my lifetime.

And yes, loops are quiet, but if not deployed vertical, they will be listening to space mostly! A loop deployed vertical, especially a Delta loop and polarized vertically, will amaze you!

http://www.amateurradiosupplies.com/delta-loop-antenna-s/104.htm


A little story for you. I once had an intermittent noise that would knock my RX out. It would come on and be 10 over S9 with a really gnarly DC sound. It would be on for 2 to 3 minute, then go off for 5 or 6 minutes, and repeat. Really annoying. I got a tech from the power company on it and he spent about an hour and came back to tell me that he had found the source. It was an aquarium heater in a house two doors away. They were willing to replace it but I went ahead provided them with a new quality heater and the problem went away. I figured it was the least I should do because to them it was working fine. :)




« Last Edit: October 28, 2012, 0934 UTC by Northwest Radio »
Seattle Washington running Flex-1500 SDR, Yaesu FT-897, Yaesu FRG-100, Kenwood TS-440S, Realistic DX-394/DX-160/Pro-2051/Pro-2052
OCF Windom/Dipole 173' Length @ 49' AGL, 14mhz Delta Loop, 41' Vertical, Gutters, Kites, and Fence wires