"Noise creep" and staying on top of it! Just a reminder to all who may have noise

Discussion in 'Ham Radio Discussions' started by W7UUU, Jan 14, 2020.

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  1. W7UUU

    W7UUU Super Moderator Lifetime Member 133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    Today I took a few hours after a 6-hour conference call ( :eek::eek: ) today in my home office to decompress in the shack.

    Over the last few months, I'd noticed my 80m noise floor had gone from S3 to well over S9+20!!! But slowly - not all at once.... "noise creep"

    It's been a couple of years since I did a "run the radio on battery and kill all the breakers" so I built a nice fire, got the shack to a cozy 74 degrees, then killed the AC 100% (except our well pump, confirmed NOT to be a noise source).

    One breaker at a time, with my wife N7ANN monitoring the S-Meter of the IC-7300, sure enough the culprits began to appear one breaker at a time. As I turned on breakers, Anne would call out S-Meter changes - the instant a breaker showed an increase, I'd be off to find the source.

    First found? Cheap Chinese Baofeng charger for a UV5R that's part of our "5-acre intercom" that had recently been added in the carport, 75 feet from the radios!!! That knocked me down from 20-over 9 to 10-over.... that's a positive change. Oddly, I have another Baofeng UV5R in the shack that the power supply is NOT noisy - not at all.

    Next item: cheap Chinese Digital TV receiver for the 65" man-cave screen used for football and movies... unplugging that receiver knocked my 10-over-9 to S6!!!! I just left it unplugged - when I next watch a game, I'll plug it in since I won't be on the air, unplug it after.

    Last item and a big surprise: My old Yaesu CRT station scope in one operating position - THREE S-units of noise just being plugged in and not even turned on!!! I just added that to the lineup a couple months ago and never noticed at all. Tried some ferrite "clamp on" noise filters to no avail.

    Two long 48" power strips w/surge suppression still add 1/2 S-unit each to noise - I'll ditch those soon and replace with homebrew "Edison outlets in 4-square boxes" - that will drop 1 to 1.5 units of noise. But once the noise was down so low, it was very apparent that the strips themselves were adding noise.

    But for now, I'm quite happily back at S3 to S4 on 80m and back to copying pretty weak signals.

    Just a reminder to periodically "pay attention" to your noise level, and what might be affecting it adversely.

    AE7LP, W9FL, K7TRF and 14 others like this.
  2. NK7Z

    NK7Z Premium Subscriber QRZ Page

  3. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    Excellent, Dave!

    This is why the old advice of switching each breaker off and on individually to look for a noise change doesn't work well anymore, unless there are only one or two sources of RFI present - rare these days I think.

    BTW, did you check for anything with backup batteries first?
  4. W7UUU

    W7UUU Super Moderator Lifetime Member 133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    Yes I in fact did! Just two devices: a clock and a keyer. Removed the batteries in both just to be sure but they were clean.

    The single biggest surprise was the HDTV receiver box - takes the noise from S5 - S6 clear to 10-over-S9!! AMAZING amount of RFI produced by that little box. But thankfully, I don't "watch TV" other than football games, and I'm usually not playing radio when watching a game. So the receiver box will just stay unplugged when there's no game on.

    SO pleasant to be back to normal S3-S4 "natural noise" on 75/80 and slightly lower on 40.

    It's amazing to me how as time goes by and we add more stuff or change things that the noise can creep back in and before you know it it's over S9 again!

    N0TZU likes this.
  5. WD0BCT

    WD0BCT Premium Subscriber QRZ Page

    Remember the good old days when noise problems were generally limited to bad insulators on utility poles?
    Sooo many sources out there today!
    N0TZU and W7UUU like this.
  6. W7UUU

    W7UUU Super Moderator Lifetime Member 133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    Oh, indeed! Or bad street lamps - had that problem back in 1996 with a neighbor who had a "municipal style" street light and utterly refused to service it even though I had proven it to be the cause. But finally it burned out and my noise was gone! They installed a new lamp and all was fine after that. And zero "wall wart" noise as well! Back then most all of the "wall warts" were still linear with transformers inside the plastic case.

  7. N5AF

    N5AF Premium Subscriber QRZ Page

    Speaking of which...Yesterday morning on my trek to work at 2AM I'm driving on a very rural through-the-forest road to my house and and I notice this odd flashing light in an otherwise dark sky. As I got closer, I realized the "light" was arcing and sparking coming from the top of a power pole. Where the line came into an insulator and changed directions, the power line was actually glowing for about 2-feet. Flipped over to AM on the truck radio while at the pole - wow, what a racket!

    Notified the power co-op later that morning. I wonder how long a power line can glow before it breaks? :eek:

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