More RFI troubles

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brandon

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New RFI that started over the weekend that pretty much wipes out lower HF (3 to 10 megs) for me. So far I don't know what it causing it but will report once I can find the culprit. Had no luck with noise cancelling.

This is how it looks on the waterfall display. Valid shortwave broadcast on 5755. Everything else is the noise culprit.


Here are 2 audio clips. One is the noise is active and the second is when whatever it is may be idle/standby.
 

ridgescan

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there's a subtle mellower buzztone underneath the loud buzztones in your clip that sounds identical to the rfi my cable/phone/net modem throws across the lowbands and certain points in some higher bands but then again that type device is on constantly so you'd have it 24/7, and you have indicated it coming on at certain times.
 

SCPD

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Sounds like some kind of switching power source to a digital device. Does the noise show up on a portable SW radio? I wonder if someone invested in the newer BPL devices that are hitting the market.

Brandon, do you see the same waterfall output in the ham bands? I was just reading the "HomePlug 1.0" specification and the powerline networking units use OFDM (similar to DSL) and operate "channels" between 4.5 Mhz and 21 Mhz. To meet FCC requirements, the HomePlug group agreed to notch out the amateur bands. I'd be curious if your 40m band was "clear" and the 5mhz band showed the above output.

The annoying thing about the above requirements is that the ARRL was involved and agreed that any RFI emission was acceptable as long there was "moderate separation" between the ham antenna source house. <sigh>
 
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brandon

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40 meters is much cleaner on the waterfall compared to above. When I tune AM mode there is a faint hint of the noise, but nothing like 5 MHz
 

brandon

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Yeah it's pretty sad all this crap that caused problems on HF. I'm pretty much forced to give up HF listening now. I'll probably sell off the gear until I can relocate to a noise free location some day. The latest RFI has just totally destroyed HF listening here.
 

zz0468

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Do you have a loop antenna where you can steer the null toward the noise source? I've also found that a loop used in conjunction with active noise canceling can be VERY effective when one or the other alone wasn't enough.
 

woebbers

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Brandon

you cant give up this quick...im the King of noise here and I just found one of my culprits...the power injector for the loop was bad or going bad..i replaced it with a RS model and my noise has dropped...I had a noise similar to that when they replaced a ballast in one of the outside security lights here...even though the light isnt on during the day the ballast stays warm because its an outside fixture...good luck in finding it...i still have a bad bad noise in the lower end of LW thats making me nuts...
 

ridgescan

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Yeah it's pretty sad all this crap that caused problems on HF. I'm pretty much forced to give up HF listening now. I'll probably sell off the gear until I can relocate to a noise free location some day. The latest RFI has just totally destroyed HF listening here.
Brandon! Noway man! You are too much of a great asset to us in here and are deeply invested in this hobby. Please don't let this kill it for you:( IMO you leaving would hurt this place pretty badly.
I only offer this suggestion fully knowing your expertise, but hoping I offer a possible unturned stone-are you 100% sure you are properly well-grounded at the antenna? Do you have a cold waterpipe nearby your feedline's entry to the house where you could take a length of AWG and at least try it to the braid? I live in an apartment building as you know, which has high power lines running not 15' from my windows, all the cable TV lines for my building run in a bundle right over my head not 5' from the end of my HF antenna, a plumbing supply store next to me etc. and I grounded at the roof, as well as in the apt at the cold water pipe. I'm telling you this because I could actually see dramatic drops in noise and more noise as each ground was connected.
How are you grounded there?
 

brandon

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Good news! I got it solved. it was a loose connection on a laptop AC adapter. Got it fixed and everything is in good order now :)
 
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nanZor

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Sounds like some kind of switching power source to a digital device. Does the noise show up on a portable SW radio? I wonder if someone invested in the newer BPL devices that are hitting the market.
I'm glad Brandon found the source. Wish I was that lucky, but I know the feeling as my neighbors went BPL on their own. Thanks a pant-load. :)

One other switching source to look out for are new solar installations. Those inverters can be noisy too. Even backyard solar enthusiasts like myself only run the old-school PWM charge controllers, and not the noisy dc-switching MPPT power trackers.
 

nanZor

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Yeah it's pretty sad all this crap that caused problems on HF. I'm pretty much forced to give up HF listening now. I'll probably sell off the gear until I can relocate to a noise free location some day. The latest RFI has just totally destroyed HF listening here.
Thankfully you got it fixed! But I can say to anyone facing the same dilemna, don't sell your gear immediately. Take a breather.

My local conditions are probably the worst - HOA antenna restrictions, neighbors running BPL - and into MY house since we share a common transformer etc.

No doubt I had to compromise being awash in this junk. That means that my antennas are built for a bigger S/N ratio, rather than gain. This means using small antennas that don't cross into noise fields, and directionality. Loops come to mind, but the BPL was such a tidal wave of noise, the fields are everywhere, making even the loop useless.

Believe it or not, I use small verticals in all this mess. I had to enlist the help of my portable ssb radio to hunt for spots in between the invisible "noise trees" where the vertical was actually quiet. They are few and far between, because it needed to be quiet across a large spectrum, but there are locations only two or three feet across where it is possible. Planted there now are top-loaded T verticals.

Horizontal antennas just crossed too many noise fields, so I was grateful that I could pick a very slim spot to place the vertical. It took DAYS to find a suitable one. I suppose I could plant an amplified unit there, but I like DIY wire antennas. Luckily, the top-load wires are just capacitive loading, and not really receiving elements per se, so that helped - but I still had to be careful.

Just don't give up - it may not be ideal being limited to very small antennas, but if you can get the S/N ratio up, it could save the hobby.
 

Jimepage

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Yea brandon good work! Glad your not leaving, yours and tokens SDRs are my fav to connect to on my sdr radio software haha. Glad you found the issue my brother.
 
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