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Common mode Noise Filters

T

The Howler

Active Member
Apr 22, 2020
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I believed that my station suffered from this noise. I have about 60' running from the antenna to where it inters the shop, 30' of which is air born.
I ran the test, disconnecting coax screw fitting, at the receiver, with just the center conductor making contact. Test result shows a full dB less noise.
The company rep I purchased this item from says if this filter is not working for me, the extra noise is coming from the center conductor?
They have no problem with sending back and refunding my money. I'm just trying to wrap my little Pea brain around this one.
 

Noise?

What kind?

In the receiver?

Is it louder in rainy weather, or does it go away during a steady rain?

More than one kind of noise. Reducing noise at its source usually works better than trying to make your receiver ignore it.

73
 
Never noticed any difference in the rain.
Yes, RF noise at the receiver.
Station electronics grounded to a single ground rod with 6’ #4 stranded.
RF noise drops full dB with PL259 coax ground disconnected at the receiver, and only touching center conductor.
 
The Howler said:
Never noticed any difference in the rain.
Yes, RF noise at the receiver.
Station electronics grounded to a single ground rod with 6’ #4 stranded.
RF noise drops full dB with PL259 coax ground disconnected at the receiver, and only touching center conductor.
Click to expand...

I had the same issue on my mobile. Ya it’s different but a few people here and an engineer said to try a different radio. I tried about everything and when I used a different radio the extra noise was gone.
 
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You kind of left us in the dark here with the noise problem. Was the noise like frying bacon, or a digital pulse, or a wine type noise. Sounds to me you possibility have power line noise, that is some power line some were is arcing causing the bacon frying / hissing type noise. Usually can be heard and even seen in the dark hours, and comes from the highest power lines on the pole.

I found another power line noise problem just a few weeks ago, my base radio has S-9 level of the bacon frying noise, just fought this a year or so ago, but the power company did fix it. I drove around in my truck listening to the AM Broadcast Band, tuned to a frequency with no station, and drove around. Found it just 3 telephone poles down, you can see the blue arc, and can hear it sizzling. Good luck, there are books written on "Power Line Noise" and such from the ARRL.

Jay in the Great "HOT" Mojave Desert.... "Next Gas 150 Miles" "Off Road Vehicles need to carry extra water, and leave their travel plans and locations with family or friends" "Extra Ammo is also suggested"
 
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It is the frying bacon type sound. Worst during The middle of the day.
I’ll try driving around The neighborhood as you suggested. Is the power company obligated to fix these problems when they happen? Also, how far away would this affect my station?
 
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Yes the power companies are supposed to fix the noisy power lines, its part of their job.

Heah sp5it was that 500 meters or 500 miles, I am sure it was meters. In the Book Power Line Noise they say the noise can get louder and quieter at different lengths of power lines from the noise source. The noise I had a year or so ago was louder about 500 meters away! Ain't dat a coo ins adence.

Jay in the Great HOT Mojave Desert 112 F today
 
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If the power line insulator is making noise, that means that it is leaking power to ground like a short circuit. This means money down the drain, so I am sure that they would love it if you would just drive around the whole city for them. And tell them which ones to fix. Haha!
 
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Its usually what we call "tracking". .. The old porcelain cut outs and various insulators are known for developing hairline cracks after years of exposure to the elements. Once the cracks retain moisture they can sometimes cause problems to those of us in the hobby. Porcelain is slowly being fazed out to polys..
 
Hello All: Well good news the Power company came and fixed the arcing high voltage lines just a few days ago. Went out for Sunday Breakfast with all the 4 wheel drive and camping crowd. Have to eat out side in the heat buts its worth all the comradery and good times.

As I am driving home I have my Stryker 955 mounted on my dash just above the steering wheel so I can keep an eye on the road easily. Listening in on 38 LSB I could hear the noise arcing telephone pole about 1000 feet away, Wow it got a hole bunch louder and stronger on the S-Meter. As I turned the corner at the noisy pole, the noise just about pinned the S-Meter. Never seen any noise get that strong. But every High Voltage noise problem has its own individual noise characteristic, that is strong noise at different power line lengths, and nulls due to different RF impedance of the power lines. And every power line noise has its own characteristic frequencies that are transmitter strong and weak.

I drive by the local High Voltage Power Distribution facility that has big transformers, insulator, switches, and No Trespassing signs. I drive by to see what noise level that power distribution facility has so I can compare it local power line noises on my portable spectrum analyzer, and radio. Gives a good reference noise level as its pretty clean.

I am thinking the Power Line Company fixed this arcing problem Sunday Afternoon in the 112F heat as a precaution to NOT start a Fire from molten metal that could have been dropped into the local thick and dry weeds. Or maybe the arcing connection welded itself together, I am going with a power line company fix. No more frying Bacon at S-9 on the base, and mobile is noise free cruising the dirt roads. I can hear a slight frying bacon noise in the far far background on the base not even moving the S-Meter, but thats ok and livable. Had to turn up the volume pretty high to hear this in the mud noise, then some big strap from skip land comes in, and blasts me perfect.

Jay in the Great Mojave Desert.... "Next gas 150 Miles"
 
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