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

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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Deke Duncan of Radio 77 returns to the air

1 Reply

Many thanks to SWLing Post reader, James Copeland, who writes:

Hi Thomas,

I’ve got something that may be of interest to you and your readers:

The legendary Deke Duncan of Radio 77 will soon have his own regularly scheduled program on WLHA, an Internet radio station based in the U.S. As many of your readers know, Duncan gained fame after being featured in a BBC program in 1974 for broadcasting from a shed in his backyard to an audience of one – his wife – via a speaker in the living room.

Now, 46 years later, Duncan will appear on his first regularly-scheduled American program from 10 a.m. to noon U.S. Central time. (3 – 5 p.m. UTC).

At this point, it may be obvious that WLHA is not your average automated Internet radio station. It used to be the campus carrier-current station at the University of Wisconsin-Madison and was recently resurrected by Alumni via online streaming. Today it broadcasts 24/7 via the Internet and features DJ’s from the station’s past as well as newcomers from all over the country (and now the world) like Duncan who obviously did not attend UW. In addition to some pre-recorded shows, the station hosts a popular “Friday Night Live” call-in show from its Madison studios.

WLHA Program Director Kevin “Casey the K” Peckham decided Duncan’s personality would be a great addition to WLHA’s “Music and Malarkey” format. Duncan, who is still living in the UK, gladly accepted the offer and added, ” My wife, Pamela is thrilled to bits that her husband has finally fulfilled his dream to be on American radio.”

Duncan will be interviewed this Sunday the 11th at 7 a.m. during the Lee Harris show, which precedes his inaugural program on the station. The interview will also be repeated from 7 – 10 p.m. on Sunday night. We’re very excited to announce this new addition to our air staff and hope many of you will have a chance to tune in.

You can listen to WLHA on Live365, through our app for iOS and Android, Radio Garden, Amazon Alexa or directly through the website at lakeshore64.com.

James Copeland
WLHA News Director

Thank you for sharing, James! I’m certain a number of our readers will be happy to hear that Deke is on the air again!

Click here to read our previous post about Radio 77.

Click here to visit Lakeshore64.com.

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Anyone sorted out how to calibrate the Tecsun PL-990?

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I mentioned in a previous post that one of the “hidden features” of the PL-990 series is the ability to calibrate the radio so that the frequency display is correct when say, you zero-beat an AM broadcaster/carrier in SSB mode.

For normal AM broadcast listening, you’d never notice the frequency discrepancy on the display. When I used the PL-990 in ECSS mode, though, my frequency display is a few Hertz off pretty consistently across the spectrum.

Our friend Gilles Letourneau (at the Official SWL Channel) recently told me that after a couple hours of tinkering with his PL-990 last weekend, he was able to calibrate it but was so deep into the process, he wasn’t able to document exactly how he achieved it. Of course, now that it’s accurate, he doesn’t want to inadvertently harm the calibration. I don’t blame him.

Big news is he’s confirmed that it’s possible.

~~I’m curious if any PL-990 or PL-990x owners have successfully calibrated their receiver. If so, please consider sharing your procedure with us!~~

UPDATE

Gilles comments…

“Tune a strong signal in AM .. like WWV then use LSB USB modes to fine tune the receiver as close to zero beat as possible. Then simply press and hold the USB key until display light flashes two times … you will be all set and calibration will work !”

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Shortwave listening in the field with the Icom IC-705 transceiver

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Yesterday, I took the new Icom IC-705 to the field for another Parks On the Air (POTA) activation. My goal at this particular activation was to make a couple of posts for QRPer.com: first, to test the new mAT-705 ATU on loan from Vibroplex, and secondly, make a short video about full break-in CW operation.

I also wanted to do a little shortwave listening after completing the activation. I had no idea what propagation would be like, but thought I’d tune around below the 20 meter band where the antenna was currently resonant.

I deployed the CHA Emcomm III Portable random wire antenna which, I must say, is a superb shortwave listening antenna for the field.

Since you can’t see the antenna in the first photo below, I marked up the second one. The blue line represents the 73′ radiator, and the green line the counterpoise:
Here’s the short video I made around the 22 meter band:

I had planned to make a few audio recordings via the built-in digital recorder but I left my MicroSD card at home. No worries, though, as I plan to make some recordings for readers to compare in the coming days if time allows.

If you have any questions about the IC-705, feel free to ask in comments.

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A new Sangean ATS-909X model in the works? Two 909Xs lead Dan to a potential discovery…

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

How two Sangean ATS-909Xs led me to news of an ATS-909X2

by DanH

I decided to buy a second Sangean ATS-909X this summer. I operate shortwave portables on batteries and wanted the ability to switch radios if one ran low on power during a listening session. I received the new radio and used it for about a week before noticing slight differences between the two 909Xs. Then I noticed big differences with the power supplies and began to ask questions. The answers led me to the new Sangean ATS-909X2 mostly by accident. Rumors have circulated for years that the 909X would be the last shortwave portable made by Sangean. It now appears that the rumors are not accurate. Thanks to an anonymous source the true story begins to appear.

I purchased my first 909X in 2015. It was built in 2014 and has been used almost every day since it arrived. The firmware is v. 1.29, the color is black. My 909X is featured in SWL and DX videos I shoot for the YouTube channel Willow Slough DX.

The new 909X was purchased early in August. This radio was made late in 2019 and has firmware v. P01. Minor changes include the color of the magnetic metal piece on the radio’s kickstand and tightness of the volume control knob which has been loosened a little. Another small change affects the beeper that sounds with certain keyboard commands. The beeper is now relatively soft-spoken.

The newer 909X features major changes made to the power supply including the AC/AC wall wart adapter. I use the 2014 909X with battery power for shortwave listening because AC operation introduces noise at different frequencies across the shortwave bands. Incidentally, internally generated noise like this happens with all of my shortwave portables when operated from AC power. The 909X is no exception. Portable SW radios made during the last 30 years just seem to do this regardless of make or brand.

The 2020 909X generates significantly less interference than my five-year old 909X. These radios have different model wall warts. The older radio is a 120 VAC / 60 Hz unit as opposed to 100 – 240 VAC / 50 – 60 Hz. The new adapter sports a ferrite core RF choke on the power line which is now shielded wire instead of small gauge zip line. So far, subtle traces of signal mixing from the new adapter are heard only when using my Sennheiser HD 280 Pro headphones. The power connection for the newer 909X is now center pin positive instead of center pin negative. Not surprisingly, the newer adapter does not work with the 2015 909X.

The search for a technical explanation for the mysterious (to me) and incompatible AC adapters required talking to several contacts. I found someone who earnestly wanted to discuss the 909X including the new AC adapter. That person floored me by saying “It’s the same adapter that will be on the 909X2.” That was last week…

Introducing the Sangean ATS-909X2

My unnamed source was happy to answer questions about the 909X2 and sent me leaked documents. The first is a sheet issued last spring listing some changes for the new radio. The second is a treasure trove: a 40+ page draft copy of the English language operating instructions for the 909X2 including line drawings. I hit gold and wasn’t even looking for it. This draft was issued earlier in the summer. I did some fascinating reading that evening.

At this point I want to caution readers that the 909X2 is very much a radio in development. The prototypes have yet to be distributed for evaluation although that is expected to happen soon. None of the features or component choices are set in stone at this point. Indeed, the very name of this radio may not be a done deal. I have heard the new model called either ATS-909X2 or ATS-909X Mk. II. Still, the draft copy of a manual that lists and explains operation of all of the many new features confirms that development is well underway. Production is rumored to begin in 2021. That date makes perfect sense as the 909X will be ten years old next year and Sangean likes to celebrate company anniversaries.

What will Sangean’s new multi-band shortwave flagship look like? The 909X2 shown in the draft booklet retains the size and form factor of the 909X to an amazing degree. The number and placement of buttons, switches, knobs and jacks remain the same. The functions of some controls may change and the location of some buttons on the radio may be switched around. A display menu will be added to operate many of the new features. Without taking a close look at how the outboard controls are labeled the 909X and 909X2 will look like siblings. A larger and much busier LCD for the 909X2 will be the most visible difference.

Here are some of the main features of the 909X2. Again, there may be changes before the final version is decided upon.

VHF AIR band in addition to LW / MW / SW / FM
Automatic Tuning System (ATS) for FM / LW / MW / SW bands
Total of 1674 radio station presets
Three memory banks for preset stations: store presets for different users and/or different areas or categories
Local/World Time with two customizable city names
FM RDS with PS, PTY, RT and CT features
Potentiometer-type RF Gain Control retained
Six-digit frequency display
SSB (Single Side Band): USB / LSB, 10/20 Hz tuning steps selectable
Three alarm timers with snooze
Larger display screen with more functions and improved backlight controls
New NiMH charge controller charges each 4xAA cell individually
Station presets/memory lock
Auto or manual bandwidth control
Selectable and band-specific bandwidth filtering for LW-MW / SW / FM / AIR
Tuning dial detents removed
12-segment bar-graph S-meter plus signal strength and signal-to-noise displayed in dB

The new ATS-909X2 benefits from innovations that Sangean developed after the 909X was introduced in 2011. I’m looking forward to firing up this new radio as soon as I can get my hands on one.

DanH

Wow! Thank you for sharing your discovery, Dan! I, for one, welcome the new 909X version 2! Sangean is a solid radio manufacturer, so I would expect the new radio to perform at least as well as its predecessors. We’ll post updates as they become available.

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