My 6500 preselector appears to not engage on 160/80/60. (WIDE at top right.) SSDR 1.10.16

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 Does anyone know what this might indicate?  I'm also seeing a very strange looking noise level with frequency domain periodicity on these bands that looks like a noisy sine wave bottoming at -110ish dBm and peaking at -85ish.  Oh, and sometimes I don't see the WIDE indication but I still have the same panadaptor view.  And on rare occasion the weird noise just goes away leaving flatline noise.  It's a puzzlement.

Any ideas appreciated.    73.... Frank / WA3NHK

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Frank WA3NHK

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  • Frustrated. I can't use my new Carolina Windom.

Posted 2 years ago

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Michael Coslo

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I'd say RFI. I haven't seen anything like that however. 
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Tim - W4TME, Customer Experience Manager

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This looks like a real signal.  You need to verify that by disconnecting the antenna when it happens and if the signals decrease significantly in magnitude, then the source is external.

Since there are intermittent, I think is is eternal.  Now you have to determine if they are local (around your QTH) or a lot farther away.  This is where the standard techniques for hunting down local RFI are applied

Regarding the preselector, your panadapter's bandwidth exceeds the 80m band. Zoom in and the preselector will engage.  Enabling the preselector may not help because the signal is within its passband.
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Frank WA3NHK

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Thanks, Tim. 

Your reminder about the panadaptor BW was spot-on.  As for the signal it's definitely external as indicated by disconnecting the antenna.  I've been suspecting foldover from the local Ch. 22 and 67 TV xmtrs (6000' away) getting past the FE filter and into the ADC.  But this morning the noise level is flat at -118 dBm with the TV xmtrs on the air, and the local 80m band sounds great so that theory goes out the window.  It'll surely return but I guess I should pursue the RFI issue in another forum.

73....Frank
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W1RE

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Anybody with horses or other animals nearby? Could it be an electric fence?

Bob
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Tim - W4TME, Customer Experience Manager

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It would be interesting to see an entire spectrum of the noise signature if it fits in a 14 MHz panadapter
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Frank WA3NHK

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When it returns I'll post a screen-scrape while zoomed out.  As of 1315ET, 14 July it hasn't returned.
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Frank WA3NHK

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Tim...here's that screen-scrape I promised you.  The RFI runs from about 1.5 to 8 MHz.  As I noted elsewhere in this thread that with Ken's help I was able to pull my head out of my butt and realize it was caused by the DC dimmers that sit between my LED driver wall warts and the LED tape strips in my kitchen.  I'm currently experimenting with ferrites, but with negligible success so far.  (We have convective activity in the area hence those horizontal noise floor bursts.).
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Jim KJ7S

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I have, and am slowly getting rid of them, or not running them when I am on radio, cheap diode replacement bulbs for your recent cf bulbs/incandescent that are way noisy and looks a LOT like this one. they use 9 watts and produce 60 watt eq(800 lumens) and they are horribly noisy: FEIT Electric Natural Daylight 5000k # ART.961032. Avoid them like the plague. They do make another model that is much better, so far as My operating tendencies go:  Same Brand, different model is "finned" and is much quieter: FEIT Electric BPCEA19/OM800/LED  13.5wts. 129 ma.
850 Lumens UL#E330072
This one Bad...  https://www.dropbox.com/s/ya4srx1hki1ql4y/20170714_140730.jpg?dl=0

This one much better:  https://www.dropbox.com/s/et8sofflub8l5i5/20170714_140724.jpg?dl=0
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Stan - VA7NF

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If the signal changes after zooming in (WIDE drops) it may be a mixing product from several very strong local signals.  
The signal is slightly louder around 3.900 so:
Is your antenna resonant in the upper part of 80M?
Is it a simple dipole or a much longer antenna?

If more than just a dipole you may be mixing several broadcast band stations.
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Frank WA3NHK

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Actually, if I zoom out the phenomenon is visible from about 1 MHz on up to around 8.  (On 40m it's visible but subtle.)   The antenna is a multiband windom but I get the same thing on my steppir vertical so I don't think antenna resonance is a major factor except for perhaps the slight peaking that you're seeing.  If you've seen my comment back to Tim I've been suspecting the local HDTV transmitters staring down my throat.  They're actually putting -8 dBM into my spectrum analyzer when I connect it to the antenna.  But I've discounted that theory for now because the RFI has disappeared (again) with the TV stations still on the air.
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Ken - NM9P

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Official Response
I have seen that same waveform here at my location in SW Indiana.  It looks similar to either: 

1) the garbage generated when my next door neighbor plugs his camping trailer in.  The charge converter on some older units is extremely RF unfriendly.   This is the closest match. to what I see on your display.  Fortunately that only happens a few days each summer, and usually on a Thursday before leaving on Friday, or on Sunday night after returning..

2) the absolute trash generated by the under counter Halogen "hockey-puck" lights in my kitchen.  They are powered by a wall-wart transformer that gets very hot when used.  I don't let my wife plug it in when I am on the air.  Thankfully the trustees are soon going to replace them with some LED versions....

3) My other neighbor's invisible fence when he first put it in.  It hasn't shown up for a year or two.  I think he had a defective unit, or had it turned up WAY to high.

You might also check for pool heaters, solar charge converters, and Plasma TV's in the neighborhood.

Good luck.

Ken - NM9P
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Frank WA3NHK

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Ken.....YOU DA MAN!!!   It was my kitchen cabinet lighting system.  I don't use that hockey puck trash from HD.  Instead I built a nice LED tape strip system using components from http://inspiredled.com  .   Their stuff is pretty good but it turns out that the 4-step dimmer that I use to control the strips at the top and bottom of my cabinets was generating very noisy edges that were piped right into the long LED strips.  When I turned on the systems just now 80m went down the toilet.  But I was using intermediate dimmer intensities.  So when I increased the dimmers to full the RFI disappeared.  For anyone interested this is the guilty component.

 http://www.inspiredled.com/products/lights-and-accessories/dimmers-and-switches/4-position-push-butt...

So now I finally get to put to good use that big box of ferrites I bought from Palomar. 

I really appreciate the help.  I owe you a beer next time you're in Annapolis, MD.73

vry73....Frank

ps:  I'll still post a WB screen scrape for Tim's benefit.
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Ken - NM9P

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Congrats...Another one bites the dust!
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Mark - WS7M

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Ken,

I think you need to give up your day job and become an RFI snooper.  Imagine, you could have a mondo big RV with antennas all over it, foldable 75 foot tower and drive around the country helping other hams zap their RFI problems!

Since you are a pastor you could stop at churches on Sundays as "The Traveling RFI Pastor".   

It would be a big hit!  :-)
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Ken - NM9P

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Thanks. I'm currently collecting good ideas for supplemental retirement income!
Planning on retiring in 5-8 years....depending on how the market treats my 403b account.....

If the economy stays good, it may be sooner. So far this year, my pension account has made more than I have!
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Mark - WS7M

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Well there you go!  Add to that the income we hams would pay you to drive to our area and birddog the RFI!   
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Frank WA3NHK

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Small update....of the four dimmers in the kitchen lighting system it appears that one of them is generating the vast majority of the in-band energy.  Later today I'll play some swaptronics to see if the problem follows that dimmer or stays with the wiring leg for that branch of the LED system.  Wiring topology might be a contributing factor since each dimmer leg is 15-25 feet long counting wire and the LED tapes.
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Tim - W4TME, Customer Experience Manager

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When I first started supporting FlexRadio SDRs many, many moons ago, we used to have a saying; "the best things about the radio is the panadapter and the worst thing about the radio is the panadapter".  Meaning you can now see what previously you only heard, so you really didn't know how bad RFI really was until you could see it.  This was at a time when very few if any radios had high-resolution panadapters. 

The good thing is that you now have excellent visibility into the RF spectrum and can find these RFI emitters and mitigate them if you have the knowledge and proper access to the RFI source.  Good luck on your swaptronics efforts.
(Edited)
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Frank WA3NHK

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Exactly.  Lacking the panadaptor and relying on only my ear and S-meter would have made it much more difficult to accurately discern the difference between the dimmers. Or to even suspect they were the source of the problem in the first place.
(Edited)
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Frank WA3NHK

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Upon further investigation I've found the root cause of the RFI to be the LED wall warts driving the LED strips in the kitchen.  I was shocked....SHOCKED!  The onslaught of Chinese quality is unstoppable.  Apparently the 4-step PWM dimmers just make a bad situation worse (especially at the lower dimming levels).  So now I'll experiment with other sources of DC.  For those interested this is the guilty party....SKU # 4842

http://www.inspiredled.com/pdf/PowerSupplies12V3.pdf


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Rich McCabe

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Glad you found it. Very frustrating.


Yesterday morning I picked up a noise on 3.970 which is a frequency I use regularly. It would not go away and this morning after 24 hours, no change.

Today I powered down all breakers in the house except the one that runs the shack dedicated circuit. Noise still there.  I switched to the Icom 9100 so I could shut down the computer and as I started unplugging stuff I found this brick running my USB hub to be causing the noise.

Here is the noise as I switched between antennas. Noise was down on my SteppIR vertical but still there.

https://vimeo.com/225834184


I would have bet money it was not coming from my house :(


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Frank WA3NHK

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60 watts to power a USB hub?  Or is it also powering your rig?  :)

I have spectral lines from DC to daylight on my panadaptor.  Typically every 25 kHz or so.  They're just a nuisance but I really should start tracking them down.

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Rich McCabe

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LOL. Just the hub. It has charging ports on it so capable of charging phones, tablets, etc quicker.  It is also a very stable 3.970 signal generator :)

I am going to start running stuff down when I find them too. 
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Rich McCabe

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Ken said "2) the absolute trash generated by the under counter Halogen "hockey-puck" lights in my kitchen.  They are powered by a wall-wart transformer that gets very hot when used.  I don't let my wife plug it in when I am on the air.  Thankfully the trustees are soon going to replace them with some LED versions.."

Same issue here Ken. Sadly I have mine running on an Astron 35m now.  I bought a 12 amp Astron and it would not run them. Don't think it was a lack of current but the kitchen light-switch powers the Astron and I dont think it liked being started that way.