Tag Archives: RFI

Radio Waves: Broadcast v Ham Radio, Marjorie Stetson’s Secret Wartime Work, Czech Republic MW Switch-Off, and PV RFI

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Radio Waves:  Stories Making Waves in the World of Radio

Because I keep my ear to the waves, as well as receive many tips from others who do the same, I find myself privy to radio-related stories that might interest SWLing Post readers.  To that end: Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

Alike, but Not Alike: Broadcast vs. Ham Radio (Radio World)

Experience in amateur radio can be a boon to the radio engineer

Starting in the 1920s and through the ’60s, almost every broadcast engineer was a licensed amateur radio operator. That has changed a bit, but the importance of being a ham has not.

Both environments involve getting an RF signal from Point A to Point B. But it is interesting to note that radio broadcast and amateur radio are similar and yet so different.

For those who don’t know much about ham radio, I’ll tell you that communicating locally or internationally, via licensed amateur radio, can be a fascinating and challenging hobby. There are about 700,000 hams in the U.S. and an equal number worldwide.

Physics

Broadcast and amateur radio operate under the same laws of science. Transmitters, transmission lines, antennas and receivers make up an RF path to convey a message.

Broadcast engineers know that signal propagation on AM and FM bands is dramatically different. It is because our FM band is roughly 100 times the frequency and 1/100th the RF wavelength of that on the AM band. Engineers also know that 950 MHz STL signals are line-of-sight and roughly a 10-times jump in frequency from FM broadcast frequencies. Each band has its own challenges in getting a useable signal through. [Continue reading…]

A Canadian opens up about her secret wartime work — eavesdropping on Japan (CBC)

Retired sergeant remembers what it was like on the ‘front line of the radio war’

At age 97, Marjorie Stetson has never told anyone her secret code number — until now.

That’s the identity code — 225 — that she typed on every page of her highly classified work for the Canadian Armed Forces during the Second World War.

The retired sergeant’s wartime work was so covert, she said, she had to sign 15 separate copies of Canada’s Official Secrets Act.

“Nobody knew where I worked,” Stetson told CBC News from her home in Massachusetts ahead of Remembrance Day. “Nobody knew what we did. Even my parents never knew what I did in the service.”

Her husband, an American sailor she met at a celebration marking the end of the war, passed away a decade ago. She never told him what she really did during the war.

Today, Stetson herself is only now learning about the true scope of her role and the significance of all those sheets of white paper she filled with encrypted messages from Japan. [Continue reading…]

Czech Republic: MW Switch-Off by 2021 (Radio Reporter)

Czech public radio ‘?eský Rozhlas‘ is stepping up its information campaign for listeners receiving mediumwave programmes, ahead of the planned switch-off of transmitters by the end of 2021. Since 1 November, more announcements have been broadcast to warn users and a call centre has been set up to explain the possible listening alternatives (from FM to DAB). In the run-up to Christmas, public radio will launch an intensive advertising campaign in the print media and online magazines on 22 November to promote the purchase of digital DAB receivers to replace analogue radio. [Continue reading…]

The impact of photovoltaics (Southgate ARC)

Seamus Ei8EP reports on the IARU Region 1 website that the 358 page Final Report on the Study on the evaluation of the Electromagnetic Compatibility Directive has now been published.

It is publicly available, free of charge, from the Publications Office of the European Union. The Political Relations Committee of the IARU Region 1 responded recently to a European Commission Roadmap on the environmental impact of photovoltaics.

The radio spectrum is an important finite natural resource which must be protected. While PV technology of itself is to be welcomed, the IARU submission pointed out the inherent problems of non-compliant installations, particularly the installation or retro-fitting of optimisers which can produce significant spectrum pollution for very limited efficiency increase.

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Radio Waves: Extreme 2001 Geo Storm, Media Ownership Rules Loosened, Germany Bans RFI-Spewing Device, Blue Jays Radio, and L-Band Patch Antenna Review

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Radio Waves:  Stories Making Waves in the World of Radio

Because I keep my ear to the waves, as well as receive many tips from others who do the same, I find myself privy to radio-related stories that might interest SWLing Post readers.  To that end: Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

Many thanks to SWLing Post contributors Troy Riedel, Dave Zantow, NT, Wilbur Forcier, and Rob for the following tips:

20 Years Ago, An Extreme Geomagnetic Storm (Spaceweather.com)

Unlike today’s blank sun, the solar disk 20 years ago was peppered with sunspots, including a monster named “AR9393.” The biggest sunspot of Solar Cycle 23, AR9393 was a truly impressive sight, visible to the naked eye at sunset and crackling with X-class solar flares.

On March 29, 2001, AR9393 hurled a pair of CMEs directly toward Earth. The first one struck during the early hours of March 31, 2001. The leading edge of the shock front was dense (~150 protons/cc) and strongly magnetized — traits that give rise to powerful geomagnetic disturbances. Within hours, an extreme geomagnetic storm was underway, registering the maximum value of G5 on NOAA storm scales.

“I was fortunate to witness and photograph the event when I was just a teenager,” recalls Lukasz Gornisiewicz, who watched the show from Medicine Hat, Alberta:

In the hours that followed, Northern Lights spread as far south as Mexico. In 20 year old notes, Dr. Tony Phillips of Spaceweather.com describes “red and green auroras dancing for hours” over the Sierra Nevada mountains of California at latitude +37 degrees. Similar displays were seen in Houston, Texas; Denver Colorado; and San Diego, California.

“Here in Payson, Arizona, red curtains and green streamers were pulsating all across the sky,” wrote Dawn Schur when she submitted this picture to Spaceweather.com 20 years ago:

“We have seen some auroras here before, but this display was really special,” she wrote.

A second CME struck at ~2200 UT on March 31th. Instead of firing up the storm, however, the impact quenched it. When the CME passed Earth the interplanetary magnetic field surrounding our planet suddenly turned north — an unfavorable direction for geomagnetic activity.

Indeed, the quenching action of the second CME may have saved power grids and other technological systems from damage. The storm’s intensity (-Dst=367 nT) stopped just short of the famous March 14, 1989, event that caused the Quebec Blackout (-Dst=565 nT) and it was only a fraction of the powerful Carrington Event of 1859 (-Dst=~900 nT).

The whole episode lasted barely 24 hours, brief but intense. Visit Spaceweather.com archives for March 30, 31st and April 1, 2001, to re-live the event. Our photo gallery from 20 years ago is a must-see; almost all the pictures were taken on film! [Read more at Spaceweather.com…]

U.S. Supreme Court permits FCC to loosen media ownership rules (Reuters.com)

WASHINGTON (Reuters) -The U.S. Supreme Court on Thursday allowed the Federal Communication Commission to loosen local media ownership restrictions, handing a victory to broadcasters in a ruling that could facilitate industry consolidation as consumers increasingly move online.

In a 9-0 ruling authored by Justice Brett Kavanaugh, the justices overturned a lower court decision that had blocked the FCC’s repeal of some media ownership regulations in 2017 for failing to consider the effects on ownership by racial minorities and women. Critics of the industry have said further consolidation could limit media choices for consumers.

The justices acted in appeals by the FCC, companies including News Corp, Fox Corp and Sinclair Broadcast Group Inc and the National Association of Broadcasters.

The associations for other broadcast networks’ local affiliates, including ABC, NBC and CBS, backed the appeals, arguing that consolidation would help ensure the economic survival of local television amid heavy competition from internet companies that provide video content. Broadcast television stations have said they are increasingly losing advertising dollars to digital platforms.[…]

Germany bans ‘water vitalizer’ over radio interference (AP News)

BERLIN (AP) — German authorities on Friday banned the sale and use of a New Age ‘water vitalizer’ device amid concerns that it is interfering with amateur radio signals.

The Federal Network Agency said it had received numerous reports that the device, sold by Swiss company Wassermatrix AG as a way to “activate” the body’s self-healing powers, was transmitting on the frequencies allocated for ham radio users.

The agency said owners of the 8,000-euro ($9,540) device, which has been sold more than 2,400 times in Germany, are allowed to keep but not use it.

Wassermatrix AG didn’t immediately respond to a request for comment.[…]

Rush’s Geddy Lee is unhappy about lack of Blue Jays radio for 2021 (Yahoo Sports Canada)

Canadian rock star Geddy Lee is less than thrilled with Sportsnet’s decision to cut their dedicated radio broadcast of the Toronto Blue Jays for the 2021 season.

Sportsnet won’t directly broadcast a separate radio feed and will instead simulcast their television broadcast over the airwaves for the 2021 season, becoming the first MLB team to do so. The decision was made to minimize travel and closely adhere to team, league, and government protocols related to the pandemic, Sportsnet said in a press release.

Lee, the lead singer for Rush, spoke about the importance of preserving a radio feed during an interview earlier in March.

Lee has been avid Blue Jays fan for years, throwing out the first pitch during the 2013 Blue Jays opener, and was a regular attendee at home games for decades.

It would be easy enough to spin this into “old man yells at cloud” in defence of a slightly outdated medium, but the sports media business is tough enough as it is, and the radio broadcast does indeed have charms that television simply can’t replicate, which is especially important for the visually impaired.[…]

L-Band Patch Antenna review (Frugal Radio via YouTube)

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Guest Post: Indoor Noise and Ferrites, Part1

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Many thanks to SWLing Post contributor, TomL, who shares the following guest post:

Indoor Noise and Ferrites, Part 1

by TomL

My magnet wire loop antenna on the porch reminded me to revisit aspects about my noisy Condo that I still needed to understand.  Some RF noise I could control if I could find the right kind of information that is understandable to a non-engineer like me.  There is a lot written about the general problem of noise and radio listening, for instance this ARRL article with web links to research – www.arrl.org/radio-frequency-interference-rfi, but I needed to get more specific about my particular environment.

I had tried some common clamp-on TDK ferrites I had obtained from eBay a long time ago but they only seemed to work a little bit.  I have since found out these are probably the ones which are widely used on home stereo system connections used to reduce noise on those systems.  There must be a better way.

The more I researched topics, like a portable “Loop on Ground” antenna, or, using RF chokes on the magnet wire loop, it dawned on my feeble, misguided brain that I was wrongly thinking about how to use ferrite material.  For one thing, the material used to suppress RF noise is made with a certain “mix” of elements, like Manganese-Zinc, that electrically “resists” a specified frequency range.  Fair-Rite has a useful Material Data Sheets web page which lists the Types of ferrite material.  For dealing with noise (at the Source causing the problem), I needed to use the right kind of “Suppression” materials and proper placement.  So, it (partly) made sense why the TDK snap-on ferrites might not fully work to reduce certain noise coming from my computer screens, LED lights, USB devices, and cheap Chinese-made power adapters.

A very good  paper is by Jim Brown (K9YC) of Audio Systems Group entitled, “Understanding How Ferrites Can Prevent and Eliminate RF Interference to Audio Systems [PDF]”.  There is a longer paper speaking directly to Amateur Radio folks, but the Audio version is simpler and it uses some of the same  graphs and ideas.  I was drawn to the very detailed Impedance measurements of many different “Types” of ferrite material used for different noise mitigation.  I remember the traumatic pain of my college experience trying mightily to understand the Van Vlack Materials Science text book to no avail.  But Jim’s paper reminded me of the importance of using the correct type of ferrite material and in an optimal way that reacts favorably in the target frequency range to solve a particular noise problem.  So, what are my problem areas?

Shortwave Noise

Loop antennas have been what I have experimented with the most.  They do not pick up as much man-made noise (QRM) and they have a space saving footprint.  Fortunately, there is a wooden porch where these things have been tried.  I had successfully built a broadband amplified “ferrite sleeve loop” (FSL) in the past.  It was useful for a while but it fell into disrepair and also the Condo building has steadily increased in noise output.  The amplifier was just amplifying the noise after a while.  I also tried phasing two antennas but found the ever increasing noise cloud was coming from all directions and I could not null it out.  I even tried a “mini-whip” from eBay but that just produced a wall of noise.

I recently tested AirSpy’s YouLoop written about before, and the results were good.  However, it seemed obvious to me that it was too small as a passive loop to capture shortwave signals strongly enough without resorting to another amplifier attached at the antenna and would not improve the signal/noise ratio.  My current solution is a unamplified stealth magnet wire loop about 32 feet in circumference.  In that article, I mention things like common mode RF chokes at both ends of the antenna connection, horizontal polarization, and basically accepting that only the stronger shortwave signals will be received in a predictable manner.  I think for now, this is about all I can do for shortwave and mediumwave noise, as far as my own Condo-generated noise. Neighborhood noise is a different topic.

VHF Noise

I then started to isolate which devices caused which kind of noise when listening to my outside amplified antennas for FM/VHF and UHF-TV transmissions.  Many consumer Power adapters make a lot of noise from VLF up into UHF ranges.  One thing I did right was to try a 10 pack of these little miracle “Wall Wart” toroids from Palomar Engineers.  One by one, I put one of these small toroids (19mm inside diameter) on my home AC adapters as shown in the pictures, and the noises started disappearing.  It does not explicitly say, but I believe it is Type 75 material which suppresses the noise generating AC adapter (at very low frequencies) when wrapped 8 – 12 times.

Most egregious of these was my CCrane FM2 transmitter.  A strangled warbling sound kept emanating from the monitor closest to my laptop. Installing ferrites on the laptop and back of the monitor were not working.  I moved the FM Transmitter and noticed a reduction in noise.  So, I put one of these little toroids on the power input of the device and the noise disappeared.  Apparently, it was picking up noise from the monitor (as well as its own power adapter) and rebroadcasting it to all my other radios!  The strangled warbler is no more, I choked it (HaHa, sick bird joke).

While looking for the monitor noise, I put the eBay TDK ferrites on all the USB ports and HDMI ports.  This has helped greatly on VHF and confirms my suspicion that these cheap TDK ferrites are indeed a common type of ferrite material.  Some informative graphs can be seen in Jim Brown’s Audio paper mentioned before.  One example might be Figure 22, which shows the #61 Series Resistance which peaks around 100 MHz when using a toroid with three “Turns”.  More confused, I could not find a definition of a “Turn”.  Eventually, in his longer paper to Amateur Radio operators, he defines it, “…is one more than the number of turns external to the cores”.  Somewhere else he describes using many single snap-on ferrites being electrically equal to just one toroidal ferrite with multiple Turns.  And interestingly, more Turns shifts the peak impedance substantially lower in frequency.  So, using the graphs he supplies, one can target a noisy frequency range to try to suppress.

I then put 6 of the TDK ferrites on the VHF input to the AirSpy HF+.  Some FM grunge was reduced and was thankful for that.  The rest of the background noise truly seems to be coming from the outside picked up by the amplified antenna.

Also, I juggled a couple of the amplifiers around and now have separate VHF/FM and UHF/TV amplifiers which cleaned up the FM reception a little bit more – https://www.youtube.com/watch?v=zkDsy95et2w .

UHF TV Quality

On a whim, I put the balance of the TDK ferrites on the FM/TV splitter input cable, 10 in all.  The FM reception did not improve but the Over The Air UHF TV reception Quality improved noticeably.  My weakest TV station now has a stable Signal level and the Quality is pegged at 100%.  This is a nice surprise since it means that now all local TV stations on UHF will come in cleanly without dropouts and I can view all digital subchannels.  I was even able to rescan and added two more low-power stations never seen before. ?

LED lights

I have common LED lights hanging over a number of fish tanks and some grow lights over an indoor plant box and can hear this noise on upper shortwave and higher radio bands.  In a future article, I will explore RF noise from lights as its own special topic. For instance, why do some LED lights generate RFI and how to know before buying (I am using BR30 spot bulbs from name brands)?  Also, there is a new kind of LED “filament” light out now that uses much smaller LED’s on both sides of an aluminum strip, greatly reducing electromagnetic noise output (or do they??).  More questions than answers.

I will explore creating my own customized AC power cord attached to the AC power strips of the LED lights.  I will need to test this for safety and efficacy, so I will want to take some time to do this right.  The hope is that, using Jim’s info, I will be able to create a broad spectrum RFI suppression AC power cord and cost less than $30 each cord.  We’ll see.

Finally, I will look at “stacked” toroids using different mixes of ferrite Types, creating a custom RF suppression better than using just one Type of ferrite material, using AC cords as the main examples. For instance, the best set of graphs in Jim’s paper, in my opinion, are Figures 21 and 24 compared to each other.  Something I did not know before is that one can not only use multiple turns on a single toroid to get a lower, peaked frequency response, but also stack multiple toroids of the same Type to get a smoother frequency response.  Then on top of this, combine that set with other Types to create a customized frequency response curve.

Radios are quieter now.  Those pesky grow lights are still a problem as well as the upstairs neighbor’s lights which seem to be on a timer, making FM reception noisy again after 5pm!

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Jack finds that chokes have a huge impact on switching power supply noise

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These “Wall Wart” type adapters can create a lot of RFI

Many thanks to SWLing Post contributor, Jack Dully, who writes:

I was putting some things in my radio junk parts box and came across some chokes. So I tried a test with my Tecsun PL-880 on battery and the Tecsun supplied switching AC adapter, with and without chokes on the adapter.

WOW!

I tuned to a vacant station on battery power with headphones on. Then on AC power, the hash and static were incredible. Putting one large choke on the adapter power cord, wrapped about four times and it decreased considerably. So I attached a second choke and once again the static & hash decreased even more, almost to the point of sounding like I was running just on battery power.

Those chokes really do work well.

Thank you for sharing this, Jack. I almost never operate my portables while connected to a power supply, so I often forget about the importance of using a choke with inexpensive, lightweight radio power supplies. Thing is, so many things in our houses and shacks are powered by these QRM generators. In the shack, I’ve added chokes I’ve picked up at hamfests to a number of various power supplies. It does certainly help decrease the noise level. I’ve even used them on power cords for other appliances in the house that tend to spew RFI.

If you ever find a deal on chokes at a hamfest or electronics store, grab some. They can be an affordable solution for those noisy power supplies we still rely on.

Thank you for the reminder and  tip, Jack!

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Lemons into Lemonade: Nick is taking advantage of Texas power outage to play radio

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Many thanks to SWLing Post contributor, Nick Booras, who writes:

I am stuck in the house in Texas, bored and with no power. So I decided to make a couple videos with my phone. One nice thing about a power outage… no RFI [Radio Frequency Interference].

This Icom 705 is an awesome radio! Perhaps your viewers might like these.

https://youtu.be/NeqwTyI1Az4

Thank you for sharing these, Nick! Yes, as we’ve noted before, power outages are an ideal time to play radio and indulge in a low-noise environment! And I agree with you: the IC-705 is a superb shortwave broadcast receiver.

I hope our readers in Texas will have power restored soon–this has been a rough week for many.

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Radio Waves: RFI rebroadcasts halted in Taiwan, City Radio, Plans to Recover Titanic Radio On Hold, and Martin visits Radio Globo and Radio CBN Radio studios

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Replica of the Titanic’s radio room at the Antique Wireless Museum (Source: Tripadvisor)

Radio Waves:  Stories Making Waves in the World of Radio

Because I keep my ear to the waves, as well as receive many tips from others who do the same, I find myself privy to radio-related stories that might interest SWLing Post readers.  To that end: Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

Many thanks to SWLing Post contributors David Iurescia, Dan Robinson, Scott Gamble, and Martin Butera,  for the following tips:

Rebroadcasts of RFI programs halt over alleged “pro-China” stance (RTI)

Taiwan’s National Education Radio has decided to stop domestic rebroadcasts of Radio France Internationale’s programs. That’s after receiving listener complaints that the station’s news programs repeated Chinese talking points that praised Beijing, belittled Taiwan, and criticized the US.

National Education Radio had rebroadcast Radio France Internationale’s French and Chinese programs for Taiwanese audiences during two daily time slots under an agreement arranged by RTI.

During a meeting of the Legislature’s culture and education committee Wednesday, KMT lawmakers said that the education ministry should investigate whether the listener complaints were justified or not. They also expressed concern about what pulling the plug of the rebroadcasts might mean for freedom of speech and the press in Taiwan.

During the meeting, Education Minister Pan Wen-chung said that the rebroadcasting agreement had been intended to foster exchanges with France. Pan said the programs originally rebroadcast were mainly focused on educational and cultural topics. However, Pan said that RTI and National Education Radio have decided to temporarily stop the rebroadcasts, since the content of the re-broadcasted programs had begun to deviate from these non-political topics.

Pan said that he had not personally listened to the rebroadcast programs. He also said that the education ministry had not been informed about the decision to halt rebroadcasts until RTI and National Education Radio had already decided to do so among themselves. However, he said that the education ministry supports the decision.[…]

Listen to radio stations from around the world with the push of a bright red button (Huckberry.com)

There’s one type of travel that’s always ready at the drop of a hat: mental vacations, or, travels of the mind. If that sounds pretty namby-pamby, wait until you see what we mean. Inside this handheld radio are 18 windows into the cityscapes of 18 international locations. Streaming live radio from whichever far-off locale you prefer, The CityRadio is a living, immediate connection to the authentic sounds, music, language, and culture of vibrant cities across the globe. Turn it on, tune in, and let your mind wander while your passport stays stowed in a drawer.

U.S. government tries to block Titanic expedition as archeologists say human remains could exist (Yahoo News)

A plan to retrieve the ocean liner’s radio received pushback as archaeologists say human remains could still be there.[…]

 

Martin visits Radio Globo and Radio CBN Radio studios

I’m sending you a PDF about my visit to the Radio Globo and Radio CBN Radio studios, all with photos, video links, lots of texts, all very complete.

It also contains an interesting interview with a quite famous journalist, here in Brazil, creator of podcast content, who worked for 2 years in international Chinese radio and currently works in CBN Radio.

Click here to download (PDF 2.5MB).

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Steve tracks down the source of persistent radio interference and gets it addressed

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Photo via Unsplash

Many thanks to SWLing Post contributor, Steve Allen (KZ4TN), who shares the following guest post:

Tracking Down Radio Frequency Interference

by Steve Allen, KZ4TN

I first noticed the RFI in late November 2019 as a steady buzz at around S9. It was present over most of the high frequency spectrum. I waited until the second week of December to see if you would end on its own, no such luck. I put an HF rig in my truck and started driving around the area to see if I could find a potential source. About a quarter mile from my home is a 161 KVA substation operated jointly by the Tennessee Valley Authority and my local electrical utility. When I parked in the driveway outside of the gated substation the sound of the interference was very strong and blanked the HF spectrum. I called the phone number on the gate and after an explanation of why I was calling I was connected to a fellow radio operator. I explained the situation and he said he would bring the issue to someone’s attention and get back to me.

A week went by and I didn’t hear back from the TVA. I called the person I spoke with previously and he said that the individuals that he spoke with questioned the validity of my findings. He was very helpful but said he didn’t have much clout with the TVA, RFI investigations were not his area of responsibility. I told him I would be happy to meet with someone from the TVA and show them what I had found. I also said I would contact my local electric utility and see if they had an RFI detector so we could eliminate their equipment. My initial contact at the TVA said he would keep trying to get someone to take this issue on and work with me to investigate. I said I would call him back next week.

I then called the local utility company and talked to someone there who was familiar with these kinds of issues. The local utility company owns the output side of the equipment at the substation. He told me he was going to perform an infrared (heat) inspection of their equipment at the substation mid January as part of their annual maintenance and will also check the low voltage utility lines near the substation. I told him that I didn’t notice this RFI until after they had a power outage nearby. He said he would try and get over earlier and check the power lines that run along the streets and look into the power outage history for this area.

All during this time I kept a daily log of the RFI including time of day, frequency effected and S unit level. I also logged the weather conditions. To eliminate the electronics in my house as a possible source I connected my transceiver to a 12 VDC battery and shut off the mains circuit breaker, the RFI did not change at all. I also visited the ARRL webpage that provide information on RFI including recordings of known RFI:

http://www.arrl.org/radio-frequency-interference-rfi

The ARRL is the best source I have found in finding and fixing RFI.

By December 27th,  no word back from anyone. I assumed that they were off for Christmas but decided to write a letter to the TVA as a follow up to what had happened so far. In early January I received and email from one of the TVA engineers who said he would contact a field engineer who would contact me. The next day I received an email from the field engineer who said he was going to be in the area on another job but would meet me at the substation.

So, of course as soon as I am making headway with finding the problem the RFI diminished to the point of not being a problem. By this time here in Northeast Tennessee the winter temps are in the 40s and the humidity is lower. For whatever reason, the RFI ended. I met with the field engineer and we agreed that if there is no RFI there is nothing to search for.

Fast forward to August, 2020. In June and July I had been operating digital, mostly FT8. I usually had the volume control at zero and as it was summer I was doing no shortwave listening. One day I decided to tune around the bands and found that the RFI was back as strong as it was during December at S4-S9 from 2-30 MHz. I emailed the principal engineer I had previously been in contact with at the TVA and he told me he would contact another field engineer and that he would come to my house with an RFI locator and start a thorough investigation. The next day I received an email from the field engineer and we scheduled a time for him come over.

Upon his arrival he connected his RFI locator to my vertical antenna and tuned across the spectrum. The locator immediately displayed the signal. He captured an electronic image and said that he could now drive around the area and try and find a match. A hour and a half later he called and said he was unsuccessful and wanted to come back  and make sure the signal was still present. Sure enough, it still displayed on his locator and he was puzzled why he could not find a similar signal while driving the area. He said he would send a copy of the recording to the TVA engineer and get back to me.

A few days later I heard back from him and he wanted to come over again and make another recording. I believe after discussing this issue with his supervisor he was going to use a different method of searching the area. After a couple of hours I received a phone call from the field engineer telling me that he thought he had found the source of interference. Using a parabolic antenna he had found two different utility poles that appeared to have defective lightening arrestors on them. Both are within a quarter mile of my QTH. These poles are the responsibility of the local electrical utility not the TVA. He said he would contact them and follow up with me in a few days.

In a couple of days the interference was very low to nonexistent. Shortly thereafter the engineer contacted me saying the local utility company had completed the repairs and wanted to know if the interference was still present. I said I hadn’t hear it in a couple of days and I would get back to him if it returned. A couple of weeks later I received an email from the field engineer detailing the incident, what he had done to locate the interference, and what was done to repair it. In his email he stated the service was provided at no cost by the TVA Right of Way and Elizabethton Electric Department through TVA’s Comprehensive Services Program (CSP). I am so appreciative of the Tennessee Valley Authority. The airwaves are now free of manmade interference and I am looking forward to another winter of operating and listening to shortwave radio. Here in the 21st century there are so many electronic devices that are capable of causing RFI. I am very thankful that my station is RFI free (for the time being).

Steve Allen, KZ4TN
Elizabethton, TN

Thank you so much for sharing your story, Steve. Only recently, we posted Emilio’s article about tracing interference to poorly made switching power supplies. Thank you for sharing how you approached your local utility company, in your case, to resolve your RFI!

Very encouraging! Readers note that you don’t always have to live with persistent RFI. If you know the source isn’t coming from within your home, sometimes it’s simply a matter of getting your local utilities company to investigate.

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