Technical Topics > Equipment
Noise around the house
NJQA:
Some noise sources you might not suspect:
https://youtu.be/ewcemoXLzcU
I use switches like this to turn off noisy items (like my Keurig) when I am not using them:
https://www.amazon.com/Oviitech-Grounded-Outlet-Adapter-Indicator/dp/B0747N2Z66/ref=sr_1_4_sspa?
Finman:
--- Quote from: NJQA on March 04, 2022, 1251 UTC ---
Some noise sources you might not suspect:
https://youtu.be/ewcemoXLzcU
I use switches like this to turn off noisy items (like my Keurig) when I am not using them:
https://www.amazon.com/Oviitech-Grounded-Outlet-Adapter-Indicator/dp/B0747N2Z66/ref=sr_1_4_sspa?
--- End quote ---
Unfortunately, there are way too many noise sources in my home, and probably most homes for that to be practical.
If your antenna is on your home or close to it, you have a multitude of single frequency and wide band noise sources to content with... and of course, then there are your neighbors. I had a reminder of this recently during an ice storm that hit here a couple of months ago. A wide spread power outage gave me a chance to do some DX'ing with my trusty Icom 705 on battery power. WOW..... SO QUIET!!! it was unbelievable 8) You can certainly do that in your own home by throwing the main breaker but when the entire area is out... that's a real "local noise test"
So what's the solution? I gave up years ago in the fight to locate and eliminate all my local noise sources. I discovered an easier way to a lower my noise floor was to use one of the noise cancelling phasing devices. This is a device that goes between your main antenna and receiver. There is a "noise antenna" input that you connect to a shorter wire very close to your house. I use an 8ft piece of wire taped vertically against the side of my house. The idea is noise that arrives on your main antenna AND the noise antenna (local noise) can be phased out sometimes almost completely. It's amazing, it works. There are some disadvantages like it has to be re-tuned when you make a big change in frequency... Having several noise antennas to choose from makes it really effective.
JustGreg:
Getting back into the hobby after a few years, I found many sources in my house and neighborhood. I found dimmable LED light bulbs are much more noisy than non dimmable ones. The non-dimmable LED version are tolerable if you can keep 3 feet or more from your antenna. The four foot LED light fixtures, which are replacing older fluorescent ones are terrible. My solution keep them off during listening sessions. Most portable computer supplies are very bad. I had to use several clamp on ferrite cores to tame mine. USB phone chargers and some tablet chargers are very bad. I went through all of mine to find the lowest noise ones.
A real surprise was my neighbor's solar panel installation was a major source of HF noise. The good news for me, I found a location far enough away from the power lines for my HF antenna, which minimized the noise pickup.
Most of the high efficiency power supplies are great EMI generators. Part of the problem is the FCC has decided that those devices have no radiation limits for frequencies less than 30 MHz. Now you know why the medium wave and short wave bands are so noisy.
kris:
Hi Finman -
I live in a tall building and have a high level of disruption.
Shielded antenna cables, grounding cables, ferrite rings, power filters do not help much.
Your method is probably the only good solution to the problem!
Write something more closely about how you couple the antennas together, how you phase them, and how you adjust the attenuation level.
Thank you in advance on behalf of all the oppressed!
Finman:
--- Quote from: kris on March 04, 2022, 2338 UTC ---Hi Finman -
I live in a tall building and have a high level of disruption.
Shielded antenna cables, grounding cables, ferrite rings, power filters do not help much.
Your method is probably the only good solution to the problem!
Write something more closely about how you couple the antennas together, how you phase them, and how you adjust the attenuation level.
Thank you in advance on behalf of all the oppressed!
--- End quote ---
Hi Chris;
Glad to help!. here's a few links to some of the available noise cancelling phasing units.
https://www.dxengineering.com/search/part-type/antenna-phasing-and-noise-cancelling
https://www.hamradio.com/detail.cfm?pid=H0-002235
https://www.ka6wke.net/projects/hf-noise-reduction
There are more of these devices than are listed in these links. There was a kit being offered on E-bay a while back but it's no longer available. I only have experience with the MFJ-1026 and the Timewave ANC-4. Download the manual for the MFJ unit, that will give you a better idea of what's required for an install. You basically adjust the Main antenna gain, the noise antenna gain and phasing controls while you watch your S-meter (or just listen) to null out the noise. You will need to experiment with different noise antennas to get the best results.
I plan on homebrewing a design based on some online ideas (like the one below) once my new workshop is completed but for right now, the MFJ-1026 works well in my temporary shack.
https://www.qsl.net/va3iul/Receiver_Noise_Canceller/Receiver_Noise_Canceller.htm
Hope that helps
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