Newbie RF Noise / Noise Floor Question

snacey0103 · February 3

I think that I have been facing a severe boradband noise problem at my home in a closely packed residential neighborhood of San Jose, CA - but I am struggling to interpret what my Flex Panadaptor display is telling me. Please take a look at the following snapshots from my SmartSDR Panadaptor on several bands - frankly all bands from 6 - 160 look the same with the variation seeming to be determined by the RF Gain defaults on each band.

In each of three cases (10M, 20M and 40M) I set to a Wide Digital Mode, Panadaptor bandwidth set to Min - and two cases - with an antenna and without.

10 meters (without antenna):

Screenshot 2024-02-02 at 11.30.35 PM.png

10 meters (with antenna):

User: "Screenshot 2024-02-02 at 11.29.40 PM.png"

20 Meters (without antenna):

Screenshot 2024-02-02 at 11.36.00 PM.png

20 Meters (with antenna):

Screenshot 2024-02-02 at 11.36.53 PM.png

40 Meters (without antenna):

Screenshot 2024-02-02 at 11.38.56 PM.png

40 Meters (with antenna):

Screenshot 2024-02-02 at 11.39.49 PM.png

And, finally, a wide bandwidth view on 40 - but it's the same on all HF bands):

Screenshot 2024-02-02 at 11.43.08 PM.png

So, can someone help me with a first pass interpretation of what this is telling me about my noise environment and whether this looks like potential powerline of other noise so I can start in a direction to solve this?

Thanks for any help.

Scott, KK6IK

VE7ATJ_Don · February 3

Hi Scott... wow, that doesn't look good....

First off, have you adjusted your AGC-T correctly? There are Youtubes available showing how to do it, and it's described in the SSDR manual. Frequently, this helps tremendously.

Maybe start by trying to locate the source of the noise, and let's first eliminate a problem within the radio itself. Is there a friend ham you can visit and try your radio on their antenna? If the same problem persists, then it might be something awry in the Flex itself. If everything works normally at their place, then we know the radio is fine and it's your location.

Next is to find the source of the noise. Is it being genrated within your home? Is there any way you can run the radio on battery and turn off ALL the power to your home, at the circuit breaker panel? If the noise disappears, then we know it's something in your home. Then it becomes a case of switching circuits/things off and on to find the noise source.

If the source is external, the problem becomes much more difficult. It could even be solar panels on your roof (or someone else close by!) Then, it becomes a search for ways to keep the noise OUT of your radio and that's a whole different kettle of fish, as they say....

snacey0103 · February 3

@VE7ATJ_Don Thanks for the reply.

You have validated my thinking that I have a severe noise problem here. That is my first step.

I tried the AGC-T adjustment and found that it had no impact on any band. The noise remained constant. I also see this kind of noise when I use my FT-818ND on my home antenna, so that may be a proxy for your next suggestion... but

I'll work on finding someone to allow me to connect my Flex-6400 at their station. I may also simply take the 6400 out on a POTA expedition nearby where my FT-818ND has heard very little noise. This will need to wait until our rainy season ends :) .

So. noise sources. Well, I am in a closely packed residential neighborhood with many potential noise sources. As for my house, well, yeah. We have networks, computers, LED lights, wall wort switching supplies, solar panels, house batteries, UPS batteries... the works. I will work on how to "shut the house down" but this may be easier said than done. The house has been designed to never lose power.

As for the neighborhood, I have power lines and multiple transformers within a few hundred feet of my house. Most neighbors have solar panels as well as the requisite computers and networks.... it's the Silicon Valley. So, I suspect that I have some "interesting" and possibly challenging noise abatement/mitigation work ahead in the coming weeks.

A related question - do noise cancellation devices like the Timewave ANC-4 or MFJ-1025/6 or any similar noise cancellation devices help to mitigate high HF noise floors from many sources?

Anyone else with ideas? Any suggestions are much appreciated.

Mike Steventon · February 3

I also had some really terrible noise. Even my own solar panels on the roof literally 6ft from the rig. I ended up with a REALLY expensive way out, and purchased a DX Engineering NCC-2, with all the trimmings fitted. I also use a listening only antenna as a **** receive antenna, on a rotator (a Bonito active loop from Germany) which enables me to really hit **** the QRM.

It works very well for me and I can now “zero-out” the vast majority of noise. The Flex AGCT is also a life-saver. Now, with just a few knobs to twiddle, and the rotator control, I now enjoy many peaceful QSO’S with back ground noise s3 to s5.

Not much help, I am afraid, but there is bound to be a solution for your set-up. Best of luck.

73 Mike G4GWH

snacey0103 · February 4

@Mike Steventon Great information.

Yes, wow! The DX Engineering NCC-2 is quite an expensive, but great solution. I may need to consider such solutions but hope to better understand the sources of my noise and then consider the best approach. Good to know about how you solved a similar problem!

Cheers, Scott KK6IK

DL4RCE · February 4

Hi Scott, first the broader your filter is (now 3kHz DIGU(L)) the higher the S Meter reading is. Secondly try to increase your Pre-Amp (ANT setting) till the S-Meter does not get lower. This may be counter intuitive but there is a good reading somewhere in the forum about that. If the Meter reduces with your circumstances you will notice a better S/N ratio. This may depend on your specific situation.

There are also charts out there where you can compare your specific noise level against certain areas (city/rural, etc.) and get a first impression if your situation is tending to be good or bad.

Hope this helps.

David Decoons, wo2x · February 4

Hi Scott,

Just out of curiosity, try enabling the wide noise blanker (WNB) on 40 meters with a level of 93.

in my case it was caused by power line arcing, which the power company finally resolved. It was caused by a bad insulator on the high voltage line which terminated on one of two poles on my property.

73 and good luck locating the source.

Dave wo2x

Newbie RF Noise / Noise Floor Question

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