12 & 10 meter hiss from power grid...

[oz457]

Did a test today. Disconnected my radio from the power supply and connected to a car battery. I turned off the main electricity switch of our house and the hiss (noise ssssshhhhh) went down from s7 to s1-2 with the pre-amp of my TS-480 on. After turning on the main electricity switch, the hiss was back. It doesn't really sound like 50 hz noise then going to AM, just plain hiss... sssssshhhhh. Might be some kind of signal that the electricity company is transmitting on the grid?
Now I have disconnected every possible device in the house, the hiss just won't go away unless I turn off the main electricity switch.
The problem is all over the bands where the antenna is made for (11 meters. The hiss is stronger when beaming to the house.
Would a low pass filter help? Or a balun at my antenna (currently directly feeding)? Ferrite's around all electricity cables that come from the electricity main box to the rest of the house? Any ideas are more than welcome.

Kurt

 

[wavrider]

Hello and welcome to the forum.

If the main is turned off and no noise, then the main is turned back on and you have the noise again. You have found the source.

I would recommend turning the main on, and then turning off each circuit breaker one by one to see if the noise disappears.

Hopefully one CB will make the noise disappear.

If that happens then it is time to start looking at all the light switches, light fixtures, and outlets on that circuit.

It sounds like it may be a loose wire on either a switch or some connection making the "sizzle" sound you are receiving.

It may also be the connection on your main CB in the box feeding the rest of the CB.

You have found the source, now it is time to eliminate (fix) the problem.

Good luck.

 

[Robb]

Would a low pass filter help? Or a balun at my antenna (currently directly feeding)? Ferrite's around all electricity cables that come from the electricity main box to the rest of the house?

Nope, nope, and nope.

A power conditioner might help - tho . . .

 

[KC9Q]

Waverider hit the nail on the head. You're just going to have to go breaker by breaker until the circuit with the offending device is located. Then you can go device by device on the circuit until it localized and taken care of.

I had a similar problem at home. The device was broadcasting RF for 300 feet with a 20 over 9 noise level. It even affected the Over-The-Air TV reception. Finally found the cause and had to put a switch inline to turn the device off. Switched it back on when it was needed (which isn't often).

 

[oz457]

I pick up this thread, because I am still confronted with the hiss on HF.
I now found the source: it is not caused by the eletricity grid, it is caused by the power bricks from the laptop computers in the house. As soon I just disconnect the power supplies from the computers (unplugging AT the computer) the hiss just stops.
I have this problem with dell and sony computers. I have not noticed the problem with the acer computer I also have.
Now, the thing is, these computers (dell and sony) have their power supply send a signal from the power brick to the computer and back. When this propriety signal is not received on the computer, the computer will show a message in windows and tells the power supply has the wrong wattage and is not from dell. The message will also notify the user of the computer, the battery will not be charged and the computer will run at a slower speed. The reason why I add this info, is that changing the power brick is not an option.

I have disconnected the radio from the power grid at home and run it from a car battery, and the hiss was still there. Just by disconnecting all devices at home, the computer source was revealed.

I have bought tons of clip on ferrites, none of them have helped.
I am aware that my antenna is close to the roof, and the antenna's are all direct feeded. So I also bought a 1:1 isolation balun but I still wait for the item to arrive. A also ordered ferrite toroid, so I hope this will finally help.

If someone has the same experience and was able to remove the hiss, please report. It will help me to find some solution to my problem, beside just unplugging all computer in the house.

Kurt

 

[n0zna]

cordless phone?

might even be a cell charger?had the same problems...now we have bpl noise...

 

[KM3F]

Likely the power supplies are switching types.
They nearly all cause QRM due to the switching transients cause by their square wave switching oscillators.
The transients have harmonics all over the bands and into the VHF spectrum..
It's a crime for any mfger to put put out such trash without reguard for this type of interference.
All one would have to do is use an Oscilloscope and use the probe to sniff the sources to get this education and proof.
Most are housed in a plactic case that provides no shielding.
Seems were all slowly losing to this type of trash.
Since this rf trash is broad banded no 'rejection' type filter will work.
Only possible chance is mounting the brick in a metal case and bypassing the AC in and output leads and using ferrites, even then only a reduction might be accomplished because the computer may still radiate the trash/hash that gets out on the leads.
Good luck.