NOISE, NOISE, EVERYWHERE, NOISE

(This post is an edited version of an article I wrote for "The World of Shortwave Listening" column of The Spectrum Monitor magazine - August 2020 issue. Further details on this excellent publication are available at www.thespectrummonitor.com)

Autumn colours on the local "rail-trail" near my home.

Mount Evelyn is a semi-urban, semi-rural location about 45 kilometres east of Melbourne, the southeastern part of Australia. When we retired ten years ago to this lovely mountain region known as the Yarra Ranges, noise levels on the shortwave bands were quite manageable. At times, it might rise to perhaps an S3, but hanging a variety of antennas cut for a mix of bands and erected in different directions certainly allowed for some flexibility and control over the local man-made noise.

Previously, we lived in a highly urbanized environment where 24-hour S9 noise levels prohibited any SWL or Ham activity from home. But moving to more spacious living at Mount Evelyn allowed me to drag out the radios, string up those wire antennas and really enjoy again the hobby that was such a part of my youth.

But over the past two years, I have noticed an increase in local man-made noise around here. The level of general electrical hash on the bands has increased markedly. At certain times of the day, the S-meter rises to between 5 and 7. And it is not always predictable when the noise levels rise and fall.

Recently, the local electric company undertook significant maintenance of power poles and wires in an area not far from here. So, the entire region was without power for about seven hours. Fantastic, I thought! I'll hook up the Yaesu FTDX3000 to the 12v sealed lead acid battery and do some daytime DXing right here in the shack in a totally noise-free environment. Once the lights went off, I fired up the rig and tuned the bands in search of weak signal DX delights.

Err….well, not to be! Indeed, the results were somewhat underwhelming! It was disappointing to find just how much man-made interference was evident on the shortwave bands, even though such a large area around Mount Evelyn was without power. The hash was still registering a steady 3 on the S-meter. Certainly, it was better than when the mains power was in regular operation. But in the past, when the power had been off, the noise dropped immediately, and battery-powered DXing from the radio shack was an absolute pleasure. But alas, not on this occasion!

So, I began thinking about why this was so. What is going on here? I suspect that the electromagnetic interference we hear from our receivers these days is so prevalent that even noise from some distance away is partly propagating into the local atmosphere. Think of each noisy power line as an antenna. Think of each noisy switch-mode power supply, television and electrical device as broadband transmitters radiating through household and commercial building wiring that then act as antennas into the atmosphere. 

All this noise from our gadgets radiates into the air around us, acting like a dome and covering us with unregulated and often non-compliant RF noise. So, even though the mains power may have been off in my location, the electrical static from neighbouring suburbs and towns could still be heard on the shortwave bands. That's what I mean by the noise propagating into the atmosphere. I don't know if this is an accurate explanation. But it's interesting to speculate where the RF interference is coming from, despite such a large area being temporarily disconnected from the main grid. What I do know is that when I am DXing out in the great Australian bush and forests, far enough away from civilization, the noise simply falls away to nothing.  

Start First in Your Own Backyard

Here in Australia and some other parts of the world, specific electromagnetic compatibility (EMC) regulations govern electronic items made and imported into our respective countries. Many products marketed by online sellers or imported directly by a consumer will often escape any detection and regulatory action by authorities. But even product distribution by major manufacturers and sold in big-box stores are not always meeting electromagnetic compliance standards.

A few years ago, I owned a Samsung monitor purchased through a major electronics retailer that gave me real issues in the radio shack. When I first switched it on alongside the HF rigs, this monitor dropped carriers every 20 kilohertz across the bands against a background of S8 switch-mode noise. The only successful way of getting rid of the hash was by throwing away the monitor's power pack and connecting it to a regulated power supply. But the harmonics remained, generated inside the monitor and radiating through both the power lead and the HDMI cable. In the end, the problem was solved by some large #31 clip-on ferrite chokes on both those cables. Check out my video on this wretched Samsung monitor at https://youtu.be/J_1jRfnvp4g. 

Power packs, computers and their internal power supplies, modems and routers, and other electronic devices in the radio shack can make life quite difficult for the ham and shortwave listener. Long gone are the days when, as a young SWL growing up in the 70s, I could listen to my valve receiver and observe that the only noise being heard on the bands was atmospheric noise. I have tape recordings from that era to prove it!

A Step-by-Step Approach to Detective Work

So, in tackling the noise problem on HF bands, the first thing to do is start looking in our own homes. It's time to play detective! One of the best ways of doing this is to start with the mains power supply for the entire house. Here is a step-by-step guide to discovering the suspect devices:

1. Turn off every household electronic device, including your gear in the radio shack.
   
   
2. Turn off the power at your house’s electrical circuit breaker panel (we call this a “switchboard” here in Australia). Head back to the radio shack and get a noise reading from a portable shortwave radio with a short antenna. Of course, this can also be done with a battery-powered desktop receiver, but the portable radio is best for moving around the house to check different devices.
   
   
3. Switch the house’s electrical power back on. Head back to the shack and recheck the portable radio for any increased noise.
   
   
4. Go through every item in the radio shack, one by one, switching them on and off to see if any noise is appearing while holding the radio near each device. Check more than one frequency. Because some electrical interference can vary in intensity on different bands, you will need to check at least a few frequencies across the spectrum to be sure.
   
   
5. Identify any problem devices. Make a list (a clipboard, paper and pen are perfect for this job) with your observations, and note those parts of the spectrum where the noise is worst. It may be that a few devices are producing only a small amount of noise. However, the cumulative effect of all these noises can significantly raise the overall interference levels.
   
   
6. Now it's time to check the rest of the household for our other noise-makers. Switch each household device on and off, one at a time, and take readings from the portable radio. This laborious and time-consuming task will probably take an entire afternoon. However, this process will identify those household devices that are individually and cumulatively adding to the overall noise floor as picked up by your receiver.
   
   
7. Once you have your list, your tests are completed. Remember to turn back on your necessary household devices. Don’t forget the refrigerator (….I speak from experience here!)
   
   
8. Pro Tip: This detective work is best undertaken when the rest of the family is away from home for a few hours. Ask me how I know!....... 😄

A portable shortwave radio and a short antenna
to snoop out those offending noise-makers!

Once you have identified the guilty noise-makers in the radio shack and the rest of the home, then it's time to take action and buy lots of ferrite material to try and quell that noise. But remember, not all clip-on ferrite and toroids are created equal. You need to consider the right mix and specifications when buying ferrite. Various mixes will be effective at different frequency ranges. If your RFI issues are in the HF range, then you need to select the right ferrite that will choke the interference at HF frequencies. Most good manufacturers have data charts for their products so you can check out which ferrite to buy for your situation.   

Furthermore, the quality of the product can vary enormously. Much of the cheap ferrite that can be found on eBay are cheap for a good reason – either it is poor quality or the mix cannot be confirmed with any accuracy. Reputable brands like Fair-rite are excellent performers.  Or you can check out the extensive range of products at Amidon and other reliable distributors.  High-quality ferrite is certainly more expensive, but if you buy the right ferrite or toroid for the proper application, you can be pretty confident that those brands will do the job. There are plenty of datasheets and great information on the Internet to guide you here.

These clip-on and toroid ferrite (#31 material) are used on most cables here in my radio shack
and are effective across the HF spectrum. (VK3BVW photo).

However, some very cheap switch-mode power supplies used on household devices are so poorly designed that even ferrite won’t fix the problem. In that case, the PS should be relegated to the garbage bin. Purchase another PS at the required power and current output for the device. 

Other noise-makers can be found in many home ceilings - the ubiquitous LED downlights. They may come with compliance logos displayed on them, but some inferior quality lights don't always cut the mustard when it comes to EMC regulations. The issue lies in the LED drivers for the lights - poorly designed or made-to-a-budget drivers will radiate their dirty pulse width modulation (PWM) constant-current choppers. They have been known to cause QRM across the HF spectrum at distances up to 350 metres (382 yards) away! There is not much you can do with these, except replace the lot with high-quality units.

Low Noise Antennas

Once you have made every attempt to clean up the shack and household devices, it is always worthwhile checking your external antennas. Some will pick up noise more easily than others. Verticals are often prone to be noise capturers on the HF bands.  Consider looking for quiet places on your property where you can place your vertical. Some relocation experimentation may be required here.

The W6LVP Amplified Receive-Only Magnetic Loop Antenna is successfully used by many hams and SWLs.
Rotating the antenna helps to locate and null out offending noise sources.
Photo supplied by Larry W6LVP, with thanks.

Popular these days are the small loop antennas on poles that can be rotated to null out noise from specific directions. The W6LVP receiving loops and the Wellbrook Active Loop ALA1530LN are fine examples of small loops that work well both indoors and externally. Also, a quick Google search will reveal many designs for home-brew passive and active loops to have fun building and experimenting. 

For those HF radio enthusiasts with plenty of real estate to play with, consider a horizontal sky loop antenna. My first experiments with this antenna a few years ago gave very successful results. See my video at https://youtu.be/OLq3nBQppqg. Noise pickup was significantly lower across much of the HF spectrum with this antenna. That is, until it met its demise from a falling eucalyptus gum. My current horizontal loop is 100 metres (328 feet) long and is a great performer. Another of my low-noise antennas is a vertical delta loop cut for the 30-meter band. But even if you don't have much real estate to play with, consider experimenting with the smaller horizontal or vertical loops. You may be pleasantly surprised!

Beyond the Household Boundaries

Two problem areas are more difficult to negotiate outside the home boundaries. They are noise sources located in the homes of neighbours and from power lines running along our streets. Fortunately, if you can locate and identify offending power poles, most electric companies will provide maintenance crews to rectify noisy lines. More tricky situations occur when trying to solve problems with neighbours using poorly designed or non-compliant lighting and electronic devices. Firstly, tracking down a specific noise can involve extensive detective work. 

As mentioned earlier, some of the new energy-efficient lights in homes have been detected quite some distance or even street blocks away. The average citizen believes that if the device works, it isn't his problem. Why should some "radio nut" somewhere knock on his door and tell him there is a fault in his home? On occasions, diplomacy can be stretched to the limit. Keeping "sweet" with the neighbours helps in communicating the issue and attempting to arrive at a solution, especially if the solution involves the neighbour having to spend more money to upgrade the troublesome device. 

However, remember the ferrite we used in the radio shack and around the home can be just as effective on the neighbour's noisy electronics.....if they will allow you into their home to test it! The clip-on ferrite is ideal for this job because it is quick and easy to attach and doesn't involve removing the plug to install it.

The older plasma televisions are still around in many homes and capable of producing horrendous buzzing sounds that can be heard across most of the shortwave spectrum. Unfortunately, there is not much you can do if the plasma is owned by your neighbour, short of offering to help pay for a new TV with LED technology!

Alternatively, if the neighbour is unapproachable, it is worth investing in a noise-cancelling unit for the radio shack, such as the MFJ-1026 Noise Cancelling Signal Enhancer. Mine does a successful job of negating the plasma noise from a nearby neighbour's TV. The 1026 (and other products like it) is a phased system employing two antennas: the main listening antenna and another noise-sensing antenna. By adjusting the phase and amplitude when combining the two antenna inputs, the noise can be nulled or cancelled out, leaving the desired signal. The success of the 1026 depends on finding an effective noise-sensing antenna. This can often involve trialling different antenna types and locations.

Also, the unit can be fiddly to adjust, especially if you are constantly tuning across many frequencies during each listening session. The 1026 works well on plasma noise and other strong, individually identifiable noises. However, I find the device is less effective on general electrical interference or if you are trying to null a variety of different noise sources at the same time. This is because each source has its own waveform characteristics and level of interfering intensity.

The MFJ-1026 Noise Cancelling Signal Enhancer. (VK3BVW photo).

Battling electronic noise on the HF bands is a big topic and is not something we can cover in any detail here. But the links below will take you to some great references that may help when dealing with man-made noise in your neck of the woods:

QRM.GURU - A wonderful Australian website with fabulous resources for radio amateurs and shortwave listeners. Highly recommended!

A Ham's Guide to RFI, Ferrites, Baluns, and Audio Interfacing

The ARRL RFI Book 3rd Edition - (No longer in print, but you may be able to pick up a 2nd hand copy)

Elimination of Electrical Noise 2nd Edition

Hopefully, some of the ideas and suggestions discussed in this article will get you thinking about looking at options for mitigating noise issues. Good luck in your quest for "the quiet"!

73 and good DX to you all,

Rob Wagner VK3BVW

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