Noise Spikes -- newbie question

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  • Updated 2 years ago
I'm new to Flex and HF.  When I tune to the 80m band I see noise spikes (see picture) -- they are about 15.7 KHz apart and 25 db above the noise floor. They occur across the 80m band and to a lesser extent across the 160m band.  They do not occur on the 40m or 20m bands and they surface again on the 10m band.

I've tried the obvious things: turning off and disconnecting everything I can in the shack including my computer and monitors and running from Smartlink on a computer at the other end of my house.

Is this normal?  Any ideas on how to track down the source short of shutting off the power in my house?


Photo of Michael Wheatley

Michael Wheatley

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Posted 2 years ago

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Photo of W0DRO


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Michael, this looks like the RFI from a switching power supply. I had some of the same but it turned out to be a battery charger on a Police motorcycle in my neighbors garage. I also had a neighbor with a battery charger on his electric cart that did the same thing a few years ago. Good luck in finding the source. Del W0DRO
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Jim Gilliam

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If you have an AM portable radio, it will probably be heard as a buzzing sound. If you hear it, turn off all the power in your house and see if it goes away. If it does, you know where to search. If not, good luck!

Jim, K6QE

Photo of ka7gzr


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Hi Michael.

I would get the Flex on battery and shut down all the incoming power with the breaker box.



Photo of WX7Y


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This is NOT a FLEX issue, You can now just see the noise you have at your location.

What about power to your Router or Ethernet switch?  Wall warts are the most common problem and switching power supplies are a close second.

Other things that are noise generators are
some LED lighting
Florescent Lightning
Solar controllers 
Switching power supplies like your station power 
Grow light 
basically ANYTHING with a Ballast
Multi-speed motor controls like washers, Dryers, furnaces, water pumps ect. , ect., ect. these are intermittent and NOT constant.

If your speakers, Router Ethernet switch ect have a 10V to 16V  power requirement they can be operated direct from your Station Power supply.

Try turning the breakers off in you house run the radio off of a 12Volt battery and use a laptop on battery direct to the radio then if it's gone then it is in your house, if not maybe your neighbors have something. 
If it is in your home then turn on each breaker one at a time and watch it and if it comes on then you have at least found the circuit it is on and can start your search.

hope this helps.

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Bill Carnett

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That was a great question!  You can be sure others out there wondered the same.  With the constant real time spectrum scope you see all the noise you would only hear on a "legacy" radio (not sure where they came up with that term, hi hi).  Currently I'm in a very noisy location...industrial area almost....s5 noise and spikes all over.  Better at midnight.  73 es Aloha, Bill  AH6FC
Photo of Wayne


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Those noise spikes can also be cause by your power supply which you use to power the flex. Some switching power supplies are notorious noise makers that is why for ALL my radios I use the MFJ(Mighty Fine Junk) Hash Free switching power supplies, specifically I use the MFJ-4225 and have 5 of them and no issues with any of them for over 6 years in use.
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Ken - NM9P

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It has been said before (I think by either Dudley or Tim): 

The great thing about having such a great panadapter is that you can see all the signals on the band at the same time. 
The BAD thing about having such a great panadapter is that you can see all the RF junk, noise, and interference on the band at the same time!"

Ken - NM9P
Photo of Wayne


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Does someone nearby have solar panels? The charging regulators on those can also create a bunch of noise and none of the energy efficient devices have any regulations on noise since there are no standards they have to follow. LED bulbs are the worst for noise generation, does it happen only at night maybe its led street lamps nearby (within several blocks) Just ideas ...

And If you do identify them you can report them to the FCC as harmful interference and I have heard they will take action and send a notice to the offending owner of those devices mandating they take corrective action or be fined.

That is regardless of whether the owner is private or a business or a municipality, power company etc.

Of course that wont happen unless you file an official complaint though.

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Bill -VA3WTB

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The power strip is a power bar? same thing?
Wayne, take a look at this.....