Ham Radio RFI – How To Track Down and Find RFI and Noise Affecting Your Ham Station

Ham Radio RFI – How To Track Down and Find RFI and Noise Affecting Your Ham Station

Unfortunately, in today’s world ham radio and RFI seem to be synonymous, coexistent users of virtually all known frequencies.

At least that’s the way it seemed when I lived in high-rise condos as a cliff dweller for a couple of decades after selling the big house. There, I was usually successful using my MFJ 1026 noise canceling signal enhancer – once I finally figured out how to get the noise antenna right.

After all that experience, we moved into a single-family home in the Washington DC area and while my general RFI noise continued from a variety of sources, the MFJ 1026 was again able to handle most all the problems.

That is, until a few weeks ago when the RFI from Hell arrived.

Out of nowhere, I was getting an S9 plus noise that even the MFJ 1026 could not handle. I mistakenly assumed that someone in the neighborhood had bought some new gizmo that was going to cause the major problems and aggravations into the foreseeable future.

At least that’s what I thought until I drove onto our quiet little cul-de-sac while listening to my Yaesu FT-857D on 20m.

As I got closer to my house, the noise floor went from S3 to S9+. I continued driving to the end of the cul-de-sac and found that a half of a house on either side of us I got the S9 noise.

I had found the enemy – and it was me.

Cheap eBay Computer Power Supply – The RFI Noise Villain

My wife likes to use her computer in her office downstairs and also in the bedroom. So, I decided that I should buy her a second power supply so she didn’t have to constantly move that as she changed her work location.

Ham Radio RFI from a Cheap eBay Noisy Computer Power Supply

I found the one shown in the picture for under six bucks and thought that was a steal.

Penny wise – pound foolish.

Tracking Down Noise and RFI For Ham Radio

If you ever find yourself in a similar predicament, the first place to start is with the circuit breaker test:

1. Figure out a way to power your radio with a battery.
2. Turn every circuit breaker off in the house.
3. If you still have noise, it is not probably within your house.
4. If you have no noise, continue with the full knowledge that you are about to discover the problem.
5. Have a wife, girlfriend, friend, etc. slowly turn on one circuit breaker at a time.
6. Have them stop when the noise returns.
7. Note the circuit breaker and leave off.
8. Turn on all the other circuit breakers and make sure the noise is still missing.
9. Figure out what outlets / light switches / appliances / etc. are still off.
10. Hint: One of those is probably the location of the culprit.
11. Turn on remaining circuit breaker.
12. Unplug / turn off / each item in subject area until noise disappears.
13. Contact appropriate exorcist for problem device.

Well, those are the steps I took in order to discover that my problem was the cheapie computer power supply that we had bought off eBay. We bought a different power supply and no problem. I executed the noisy one by burying it alive in the recycle trash. It has never been heard from again.

Before and After Shots – A Whopping Reduction in Noise and RFI

The following is what the signal looks like after plugging the noisy computer power supply.

SDR 14 MHz Ham Radio Band Reception – With Power Supply RFI

The following is what the signal looks like after unplugging the noisy computer power supply.

SDR 14 MHz Ham Radio Band Reception – Without Power Supply RFI

As you can see, it is a much cleaner looking signal.

Use This Game Plan For Investigating All Noise and RFI

The above game plan should probably be used anytime a significant noise or RFI raises its ugly head in your ham radio world. I’ve used it a lot more than once with great success – however, beware that sometimes killing all of the power in the house as you continue your quest will eventually start aggravating the other residents of your home to the point of insurrection.

Note: This methodology will also tell you when you have a problem outside your kingdom. Isolating, identifying and solving the problem in those cases will be a whole lot more difficult and is beyond the scope of this posting. However, it may involve catapults, jousting and broadswords if negotiations fail. Just make sure you’re right before you throw down the gauntlet!

73 / 72,

K3RRR

-.- …– .-. .-. .-.
73 de Robert K3RRR
http://K3RRR.com
@K3TripleR
http://YouTube.com/user/K3RRR
-.- …– .-. .-. .-.

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