Fighting the demon RFI

St. George had an easier task.

Since I’ve finally gotten my HF radio setup in place, I’ve noticed that my home simply reeks of devices that are polluting the ether with their unwanted emanations.

Putting it another way, I am over electronic devices where the manufacturers saved a quarter by not installing filter caps or similar noise-filtering devices.

When I first tried out the new radio setup, background noise during the day was S7-S8 on a continual basis. That level of noise makes it impossible to hear a weak station. Unfortunately it was Field Day, and I wasn’t able to do much except in the immediate area of the radios.

Since then, I’ve tested Mrs. Freeholder’s patience and my wallet. I’m constantly walking around the house with an AM radio, listening for the buzz of AC and the tick, tick, tick of a poorly manufactured power supply. Allow me to regale you with some examples of what I have found.

The AC power coming into my home is noisy. I don’t know it the 40 year old buried service line coming to the house is deteriorating (as I suspect), if it’s the equally old main lines (also buried) or if the conductors are picking up noise from elsewhere and carrying it in. Anyone know what toroids I need for 200 amp service line?

I’m calling names on this one. Knowing that I was going to be pursuing this hobby, when the UPS for my main computer upstairs died, I bought a new Tripp Lite SMART1500LCDT. I bought this particular one because, as stated on their website “Removes electromagnetic and radio frequency interference that can disrupt or damage your equipment’s performance“. My assumption, and a bad one, was that the UPS would have to be similarly filtered or it would introduce it’s own RFI into the power. Imagine my surprise when I could hear the bra-a-a-ap emanating from it 1/4 of the length of the house away. Son now has that UPS for his use. I pulled an old APC, that makes nearly no extraneous noise, from another use to replace it.

The grow light for Mrs. Freeholder’s ficus tree and monster snake plant is now off and I’m trying to figure out what we will do when winter comes and those have to come inside again. That change took an S unit off the noise. Toroids did not help.

Every wall wart power supply in the place was buzzing and ticking. For the most part, liberal use of snap on ferrite beads, sometimes at both ends of the power conductor, has silenced that. I’ve found that the 12mm size is a good all-around choice, but that small ones are handy to have when the line doesn’t have the slack for multiple turns thorough the bead. The worst one was a Kenwood HT charger-no amount of turns through ferrite beads would silence that one. Fortunately, I had an old 12v transformer-based power supply from Radio Shack that I had hung onto for years. It even had the same size barrel connector. The Kenwood-provided supply is now gracing the local landfill.

In a related find, the charging pad for my iPhone was emitting a lot of noise. It would not be silenced either. Son has that as well, and I’m back to charging with a cord. It works and it’s quiet from an RF point of view.

Calling names again, this time because of poor service, I used Palomar Engineers‘ large snap-on ferrites on my incoming antenna lines to quiet down anything coming in on that pathway. Vertical antennas, such as my DX Commander, do suffer from a certain susceptibility to noise, so I thought it best to just hit those out-of-hand. Unfortunately, they charged me for the complete order, did not deliver the complete order and have not returned numerous email and phone contact attempts. I guess I’ll have to dispute that part of the charge with the credit card company.

I’ve simply unplugged numerous items, including an HP laser printer that was emitting boops, bra-a-ps and ticks even when off. After I pulled the plug, it took two minutes for whatever it was in that thing to discharge. I expect that I’ll just have to plug it up as needed.

Numerous other items are unplugged, including LED desk lamps, the rarely used TV and Blu-ray player in one bedroom and chargers for various tool batteries. While searching for solutions, I plug them in as needed. It’s a PITA, but it only inconveniences me. Some items have been donated to the local Salvation Army since they were rarely used.

At this point, I’ve been able to get the noise down to S3 or so. I keep sniffing around for sources that were masked by the now quieted items. Some things I’m going to allow to make noise, like the LED and remaining CFL light bulbs. Their noise is inaudible more than a foot away, so I’m going to hope they make only a small contribution to the problem. But I keep finding more and more things that need to be addressed. Eventually I’ll run them all down.

Two side effects is that we should use a bit less electricity, as all these devices were also vampire loads, and that some things have been deemed unneeded and disposed of in some way. Icing for the cake.

Now if you will excuse me, I swear I hear something ticking…

One thought on “Fighting the demon RFI

  1. Good luck! I pulled the house main breaker in order to hear what the airwaves "should" sound like. Obviously not a long-term solution… Touch lamps are a work of the devil, BTW.

    Walked around the neighborhood with a DFing radio (wish I hadn't sold it) and found an arcing/melting cutout that was doing a marvelous job of covering the HF spectrum. Yowsa.

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