Category Archives: Articles

Radio Waves: New Ham Radio Store, SDR Market worth $14.5 billion by 2025, Retaining 87.7 FM, and Hard-Core-DX now on Slack

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 Tracy Wood, Bill Patalon, Dennis Dura, and Mike Agner for the following tips:

Amateur Radio Field Day synchronized with radio store’s Grand Opening (Ramona Sentinel)

Ham radio hobbyists will test their emergency preparedness skills alongside All Day Radios’ Grand Opening celebration in Ramona next weekend.

The Amateur Radio Field Day, a national emergency preparedness activity sponsored by the American Radio Relay League (ARRL), will be held in Ramona from 11 a.m. Saturday, June 26 and continues for 24 hours until 11 a.m. Sunday, June 27.

All Day Radios co-owner Peter Von Hagen will coordinate his Grand Opening in sync with Field Day from Friday through Sunday. The store is at 2855 state Route 67 between Dye Road and Hope Street, and Field Day will be held next door.

Von Hagen said the object of Field Day, held annually the fourth weekend in June, is to communicate on as many stations on amateur bands as possible to test the capabilities of communications equipment. Operators will be using backup sources of power such as solar power and batteries, he said.[…]

Software Defined Radio Market worth $14.5 billion by 2025 (Markets and Markets Newsletter)

The demand for software defined radios, especially in the commercial applications, such as telecommunication, transportation, and commercial aviation, has been affected to a great extent. Due to precautionary measures undertaken by many countries to stop the spread of COVID-19, several public/private development activities have been stopped, resulting in a drop in demand for software defined radios. However, this trend seems to vary from country to country. For instance, the demand for software defined radios in Europe and the Asia Pacific has been affected by the pandemic owing to the stoppage of development activities.

Based on application, the commercial segment of the software defined radio market is projected to witness the substantial growth during the forecast period

In terms of application, the market is segregated into commercial and defense. The rising usage of SDRs in commercial applications including aviation communication, marine communication, transportation, telecommunication is supporting the segment growth. Software defined radios are predominantly used in Air Traffic Control (ATC), transportation, and telecommunication applications. They are easily upgradable and provide high data transmission rate that further enhances its usage for commercial segment.

Cognitive/ Intelligent radio sub segment of the software defined radio market by type is projected to witness the highest CAGR owing to increasing improvements in cognitive radio products.[…]

FCC Report 6/13: Has A STA Based Doorway Been Cracked Open To Retain 87.7 FM Operations? (Radio Insight)

The FCC has sent another reminder to licensees of analog low power television stations regarding the July 13 drop-dead date. If an analog LPTV has not applied for a digital CP by that date its license will be cancelled and those that have Construction Permit’s but will not be ready to broadcast digitally will need to file a waiver request but still will be required to turn off their analog signal on the 13th and cease operation until ready to begin operating with their digital facilities.

This will of course affect the thirty something LPTV’s on analog channel 6 operating as radio stations on 87.75 MHz. While some of these signals will be moving to other channels, many will be remaining on channel 6 and have spent the past few years seeking loopholes to continue to broadcast an analog audio signal past the digital conversion deadline. Venture Technologies Group, which owns five affected stations, threw the door wide open this week with the grant of a six month STA for its KBKF-LD San Jose CA. KBKF-LD, which is leased to Educational Media Foundation to air its “Air 1” network, will be permitted to continue to offer an analog audio signal on 87.75 FM in its ATSC 3.0 digital video signal.[…]

Introducing: Hard-Core-DX Slack Chat (Hard-Core-DX)

From: Risto Kotalampi

Hi all,

Hard-Core-DX has been a pioneer in connecting shortwave listeners for nearly 30 years now. In its core it has been emailing lists and web sites and some other experiments which have either spun to become popular on their own (e.g. various ham related spotting sites or Online Log which is very popular in Finland) or not. Today we wanted to try to branch out into chat using Slack.

This is not the only chat there is… IRC, Facebook, Whatsapp etc have small circles for shortwave listeners but they have all been closed systems and not enabling an environment that can be used across devices and have conversations about any topics we choose. In the corporate world Slack has revolutionized communications amongst colleagues and partners in different companies. Much of work in U.S.A. small companies happens nowadays in Slack and not so much in emails.

Hard-Core-DX has signed up and created it’s very own Slack service.
If you want to join the HCDX Slack, please click this link and create your own HCDX Slack account:

https://join.slack.com/t/hard-core-dx/shared_invite/zt-rn83gamf-_UCfo9LYUVmoIBhb0~3cSg

Some basic rules of the Slack service:

When you join it, you will see some channels that have been created already. You can join them or if you can’t find the topic you’d like to chat about, please create your own.
HCDX will not be in the business of moderating what people are creating or discussing. If you create a channel, you will choose the policies of the discussion.
This can naturally invite some abuse. We will deal with it with Slack’s policies as time comes.
You are welcome to invite your DX friends to the HCDX Slack and grow the community. Invite happens from menu in upper left corner and link “Invite people to Hard-Core-DX”
Let’s keep subjects within shortwave radio, broadcast, utility, pirate DXing & ham radio if possible to keep the service relevant to us
This is an experiment… if it doesn’t gain popularity or becomes a burden, we will shut it down. But for now, if you want to experiment and see if this is where you want to chat with your DX friends, join the fun.

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Your support makes articles like this one possible. Thank you!

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Guest Post: Jerome’s experiences as an SWL in Saudi Arabia from 1990-91

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Many thanks to SWLing Post contributor, Jerome van der Linden, for the following guest post:

Experiences as an SWL in Saudi Arabia 1990 /91

by Jerome van der Linden

From about 1986 I worked for the Broadcasting Division of Telecom Australia (now “Telstra”), in Adelaide, South Australia. This Division of Telecom Australia had responsibility for installation, maintenance and operation of Australian Government funded broadcasting services (radio & TV) such as ABC (including Radio Australia) and SBS. In later years responsibility for this was taken away from Telecom Australia and handed to BAI.

I already had a life long interest in Broadcasting and short wave radio in particular, and I was recruited into a new non technical managerial position in the then new Broadcasting Division of Telecom Australia: it was the perfect job to my mind. In this period of the late 1980s, the organisation was heavily involved in the capital works to get Radio Australia Cox Peninsula (Darwin) back into operation, after it was largely destroyed by cyclone Tracy in 1975, as well as building the three Northern Territory vertical incidence (“shower”) services at Katherine, Tennant Creek, and Alice Springs (VL8K, VL8T, and VL8A respectively). (The NT is probably about the size of a major US state like Texas). Apart from doing my non technical work, I took every opportunity to learn more and get involved in the technical side of things. On one occasion, when I knew that the technical staff would be testing the new transmission facilities on a range of frequencies, I was able to confirm with the onsite technician a booming signal into Adelaide from the Alice Springs transmitter he was briefly testing on 11715kHz in the daytime.

Alice Springs (VL8A) transmitter site in the last year is was operating (Photo by Jerome van der Linden).

As the opportunity arose, and as I was also part of the Southern Cross DX Club, I regularly participated in the Radio Australia DX program (I cannot even remember its name, 30 years later) that was produced by Mike Bird. I also contacted many rural cattle stations (equivalent to “ranches” in the US) that were spread throughout the Northern Territory to get them to report on how they were receiving the new NT HF service broadcasting stations when they came on the air. I saw it as a way of promoting the shortwave radio services throughout the Northern Territory.

My work gave me the opportunity to visit not just each of the new NT HF transmitter stations, but also included several visits to the Radio Australia (RA) facility at Cox Peninsula. While I also saw the old RA Receiving station on Cox Peninsula (dating from the period when signals were received from RA Shepparton and then re-transmitted from Darwin, in the period pre cyclone Tracy), this was at a time when that facility had already been largely dismantled.

In early 1990, I sought and was awarded a contract position with Telecom Australia’s Saudi project, and I was seconded to that from my job in the Broadcasting Division. From my own research, I knew that radio and TV in Saudi Arabia was quite unlike what I was used to, and I made it a point to take with me, on loan, a Sony ICF 2001D receiver. So it was in March 1990 that I arrived in Riyadh on a single person’s contract. I was allocated a 2 storey 3 bedroom villa for my own use among a large number of other identical villas occupied by other Telecom Australia staff, that were all located within a walled compound close to the Saudi Telecom offices.

Almost immediately, it was obvious that I would have to rely on the BBC World Service for my English news, as the KSABS radio services were nearly all in Arabic, and its TV service was even less appealing to me. I managed to string up some long wire antennas on the roof, and it was not long before I was also able to pick up services from Radio Australia. I got in touch with Nigel Holmes, then RA’s Frequency Manager in Melbourne, and was able to let him know how signals were being received in the Middle East, even though South Asia was about the limit of RA’s intended reach at that time. As my office was in the city of Riyadh some distance away, I was allocated a car for my own use, and – having found these were quite common – soon fitted it with a Short Wave capable car radio. In fact it was the one I reviewed in the 1991 WRTH.

The compound housing the many Australians and their families had its own CCTV system, and the Aussies were entertained by a regular supply of Australian VHS TV tapes. The same CCTV network was also used by Australians from the project making out as wannabee disk jockeys with their own programs before 7am and into the evenings.

As many people will recall, in mid 1990, Sadam Hussein, the then leader of Iraq, invaded Kuwait, and there was some concern he might continue and invade Saudi Arabia. As a direct consequence, radio with World news became even more important for the Australians, and the many other expats working in the Kingdom of Saudi Arabia (KSA).

An unexpected benefit to the expats living in Riyadh was the arrival of thousands of US ground forces, who brought with them their very own AFN broadcasting services which operated on FM with their own high pitched professional female DJs who played the latest pop music. This was at a time when this type of music was not heard at all on local Saudi radio, and the only source we had of modern music was the many bootlegged copies of cassette music which were for sale everywhere (in addition to pirated copies of software).

When Sadam Hussein decided to stop international residents from leaving Iraq to travel home, their roles as ‘hostages’ caused international broadcasters to improve their services into the Middle East.

That included Radio Australia, and at least one of its Cox Peninsula transmitters was used to improve the signal to the Middle East in the hours up to its daily shutdown at midnight Darwin time (1430UTC). The strongest signal in those days was a 21MHz frequency, and it mostly boomed in. I recall one evening when the transmitter’s audio sounded very suspect to me. I made a quick international phone call direct to Cox Peninsula; spoke to the duty shift supervisor who I knew personally; described the signal to him; he picked the problem; switched the transmitter off and placed another transmitter online on the same frequency which gave clean audio, that I was able to confirm to him.

A Patriot missiles being fired to intercept a scud missile on 24 Feb, 1991 (Photo by Jerome van der Linden)

It was about this time that I realised my Sony ICF2001D had a feature I could use to the benefit of all my fellow Australians in the compound. In the first instance, I was able to arrange for an audio feed from the 2001D in my villa into the compound’s CCTV system, so that – provided someone plugged the audio in correctly – the signal from my Sony radio’s line out was relayed to every other villa that cared to listen. As I was absent during most of the working day, I used the Sony’s programming feature that allowed for up to 4 separate listening sessions to be set up. Each program required a SW frequency and start/stop times to be programmed. I think each session had a time limit of perhaps 4 hours. This enabled me to set the radio up to relay BBC World Service for most of the day switching automatically to certain frequencies as appropriate, and also provided the people with some brief Radio Australia segments with news from home.

In the period prior to January 1991’s, when George Bush had promised to retake Kuwait if Sadam Hussein did not withdraw, it was also interesting to pick up Iraqi broadcasts intended for (and to try to demoralise) American servicemen. Very strong signals from Baghdad were regularly audible, I seem to recall 11825kHz being one such frequency.

In the event, about January 16, 1991 the allies invaded Kuwait from Saudi Arabia, and made devastating air based attacks on Iraqi facilities. Radio Baghdad’s shortwave service did not seem to last very long after that.

We Australians were told in no uncertain fashion that Iraqi “Scud” missiles were ballistic (hence not accurately targeted), and would definitely not have the range to reach Riyadh in Saudi Arabia. The experts were wrong however, and a couple of scuds did reach Riyadh. As our compound was in the “flight path” from Iraq to the Riyadh airbase the Americans were using, it turned out we were not in the best location! The American forces had “Patriot Missiles” set up to intercept any Scuds that got through, but nobody told us that the Patriots break the sound barrier seconds after being fired, and that they’re only capable of intercepting Scud missiles just before they hit the ground. You can imagine the sonic booms that went off the first night Scud missiles arrived: I have photo in my home that some daredevil took outside, that proves all this.

We had been told to tape up the glass on our villas in case it should shatter, and that we should leave our TV sets tuned to our CCTV channel turned on at all times, with the volume up so that if there was an air raid the staff and their families could be alerted by means of a piercing alarm sound that someone had fiendishly created. And so it was that one Thursday, when Jonathan Marks had scheduled a telephone interview with me for Radio Netherland’s Media Network, we were discussing media events in Saudi Arabia when the air raid alarm went off, and we had to postpone the rest of the interview. I seem to recall that he did call me again later the same night and we finished things off. I never did get to hear the program, or I would have recorded it! As far as I know, it’s not one of the programs that Jonathan has been able to find to include in his on line media vault. If anyone else has a copy of this early 1991 edition, I’d love to hear it again.

As the experts had been wrong in their assessment, it was decided that most of the Australians would be removed from Riyadh, and I was sent to do my work from Jeddah, for about 6 weeks. Again it was a slightly different media environment, and while interesting, I missed the ICF2001D, and bought a cheap multi band analogue portable to be able to keep up to date with BBC World Service News broadcasts.

By early March 1991, most of the fighting was over, and it was safe for me to return to Riyadh, where I worked for another two or three months, before returning to my normal job and family in Australia.

Off-Air Audio Recordings

Radio Baghdad to US Troops (1990):

BBC World Service News of the start of Desert Storm (January 16, 1991):

Radio Australia announcement by the acting Foreign Affairs Minister (January 16, 1991):

AFN Riyadh (Brief clip of Army Sergeant Patty Cunningham signing off her shift):

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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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Dan notes that premium receiver scammers are back on eBay

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Many thanks to SWLing Post contributor, Dan Robinson, for the following guest post:

Premium Receiver Scammer(s) Back

by Dan Robinson

From time to time here on SWLing Post, we have alerted readers to scammers using multiple eBay addresses to attempt to rip off unsuspecting potential buyers and using old photographs of usually premium receivers to do so.

Well, whether this is one scammer or many, he is back. See the photos attached here, which show what is surely a fictitious eBay ID and what appear to be legitimate photos of a Panasonic RF-8000, one of the most sought after of the large portables from decades ago.

It’s not until the 4th photograph that this person provides that you see what’s involved in the scam, which is the scammer noting that he is “selling this on behalf of my company” and that the radio can be purchased “at the buy it now price only” The scammer then provides an email address to get around the standard eBay auction process, adding that he does not respond via Ebay messaging.

I have continued to alert eBay to these scams, and to their credit eBay has taken down many of these items in recent weeks and months, though occasionally eBay does miss these. eBay also does not make it immediately clear as to how to report items like this (HINT: you have to scroll down the page until you see a tiny REPORT link on the right side which takes you to multiple categories. These scam items fall under “LISTING PRACTICES” “FRAUDULENT LISTING ACTIVITIES” and “YOU SUSPECT THAT A LISTING IS FRAUDULENT”

If eBay has successfully already taken a scam item down, you will then see a confirmation page saying the item could not be found after refreshing the page. Very often, even after reporting an item, the identical item will show up within seconds or minutes under a completely different eBay ID (see the 2nd photo here on the Panasonic RF-8000 which shows a changed eBay ID)

Receivers most often seen on these scams include: AEG 1800A, Panasonic RF-8000, and usually other premium sets, and the tip off to the scam is that the seller/scammer usually always starts the price at $1.00 or $34.00 or similar level. In the case of the AEG 1800A, the scammer consistently uses the exact same photo of this rare receiver, from a sale that completed years ago.

I would encourage eBay users to join me in reporting scams like this — eBay certainly appreciates it and if you have eBay “Concierge” level service, which I do, it’s sometimes a help to them to get online and chat with eBay about the item and your report, especially if the eBay algorithms have failed to spot and take down a particular scam.

Thank you for sharing this, Dan. We appreciate insight from radio enthusiasts like you and Paolo. As Dan suggested, I encourage you to report listings that are obviously fraudulent to eBay. They will investigate the case and take action if it is a scam.

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Build an affordable (but stealthy) Magnet Wire Vertical Loop antenna to mitigate condo QRM

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

Magnet Wire Vertical Loop Antenna

by TomL

For those of you in a noisy condo like me, the environment does not give me many options. I was experimenting with a YouLoop on the wooden porch with somewhat acceptable results. For its size, it is an excellent performer, especially on the lower bands. Here is a very interesting review of the YouLoop, including close-up pictures of the innards of the phase inverter and 1:1 balun, by John S. Huggins. However, it is not waterproof and I was concerned about the ice and snow ruining it. I could tape up the connectors with waterproof tape but I also wanted something with a bigger capture area. A magnet wire stealth antenna might be just the thing!

I just happened to have a waterproof 1:1 ATU balun from Balun Designs that I was going to use for future Amateur Radio use whenever I get around to passing the next level test; it is total overkill for what I intended to use it for. It would make a good connection point and (this one) also acts as an RF choke as well. One can make a 1:1 balun by buying the right Type of ferrite core and winding it yourself. Here is just one idea from Palomar Engineers.

So I dusted it off, went to a local store to get a 100 foot spool of 26 gauge magnet wire and tested it strung up around my living room. It came out to be a rectangle about 42 feet in circumference. Results were usable. I expected lots of noise and there is a great deal across the bands, so only the strongest shortwave stations were received. However, I was surprised by how strong the mediumwave band was and good to listen to without an amplifier.

I am ambivalent towards trying to perfectly match the impedance since this is a broadband receive-only antenna and the impedance will vary greatly over MW and SW bands. And I don’t want to mess with a remotely controlled tuned loop since this antenna was destined for the outdoor porch. I tried a Cross Country Wireless preselector at my desk but had some mixed results. I later found out, by disconnecting things in series, that the preselector inline raised the noise level about 5 dBm, so I took it out for now. Perhaps it needs more internal shielding or the connecting cable is bad.

Polarization is an issue, too. I have read that most man-made noise (QRM) is vertically polarized, so why would I use a vertically oriented loop? Then I saw David Casler’s video on loop antennas where he explains that connecting a vertical loop antenna at the bottom or the top makes it horizontally polarized (connecting the coax on the side makes it vertically polarized). I never knew that! Horizontal polarization will mitigate some of the offending QRM as well as match the polarization of mediumwave band transmitters. Furthermore, I read that a horizontal loop will have poor signal pickup at low frequencies because it is not high enough off the ground, similar to a horizontal dipole. For now, a vertical loop connected to facilitate horizontal polarization is what I want.

A note about wire size. People make a big deal about it but those are mostly amateur radio people. Transmission depends on efficiency so things like wire size, skin effect, standing waves, and other things matter (see here, for example). With a receive-only antenna it is OK to use very thin wire. Resonance can matter if you want the last ounce of signal strength with an antenna tuner, like in high-Q type loops where the bandwidth is very narrow and you are using a multi-turn loop with variable capacitor and a pick-up coil of wire to the receiver. Comparatively, my simple loop is depending more on a single turn of wire, the aperture size, length of wire for its performance, and carefully isolating the feedline coax using RF chokes at both ends.

Here is one example of a strong station from Cuba I was able to record because WLW was off the air for some unexpected reason.

Radio Reloj, Cuba 870 kHz (At the end, you can hear WLW come back online with CBS news):

Side note about Radio Reloj on Wikipedia, the strange format seems to fit well with a totalitarian regime, including a “corrector” who “corrects the content/writing errors to meet the requirements”. Read the wiki link for yourself. Not a society I want to live in, thank you very much!

Example of 80 meter band performance – Greetings to a new person from members of the “Awful, Awful, Ugly Net”, 3855 kHz:

Encouraged by the results, I “installed” the magnet wire around the support beams of the wooden porch, wrapping it carefully to create a square loop. Holding it in place is a brick at each bottom corner since I am not allowed to nail anything into the Association-owned porch. The length came out to about 32 feet (8 feet per side), so I trimmed it and connected to the balun. I also added an RF choke at the Airspy HF+ input from Palomar Engineers which helped bring noise down a couple of S-units. That might not sound like a lot but by also shutting off the living room air filter and an AC switch with “wall-wart” AC power adapters on it, I was able to reduce the noise a little bit more. There is still a lot of noise from the neighbors, so it is not a perfect situation.

Here are two examples of reception with the outside installation.

Gateway 160 Meter Radio Newsletter, broadcast (in AM) by WA0RCR every Saturday on 1860 kHz:

Side note about the Radio Newsletter. I stumbled on it when using the YouLoop and found that some of the content is very interesting and informative. Of course it is geared mostly towards amateur radio but some of the news items are of general radio interest as well. It airs 1pm Saturday through 2am Sunday, USA Central Time. Obviously, many segments repeat during that lengthy timeframe and reception depends on propagation from Missouri.

KDDR 1220 kHz, West Fargo, ND station ID (presumably “nighttime” power of 327 watts):

The shortwave bands are still a noisy disaster but signal levels are higher compared to the YouLoop. Only the strongest stations come in like WRMI, WHRI, Radio Espana, Radio Habana, and CRI. And I can hear the loudest amateur radio operators.

Just for grins, here is Radio Rebelde on 5025 kHz when band conditions were above average:

Another phenomenon I am looking into is the reception pattern of a vertical loop. Less than 1/10th wavelength, the null is through the center of the loop. At one wavelength, the null manifests in the plane of the wire loop. They are too close to phase them but switching between two directional loop antennas might improve reception depending on frequency. We shall see in the future.

At least for now, I have a decent mediumwave band which performs better than the useful CCrane Twin-Ferrite amplified loop antenna that was used in the (noisy) indoors, I can hear the 160 & 80 meter amateur bands better, and the reception of the strongest shortwave broadcasters are more predictable. Not bad for four dollars of wire!

Brilliant, Tom! Again, I love how you’ve not only made an inexpensive antenna, but you’ve even done it within your HOA regulations. You’re right, too: if you’re not transmitting into an antenna, it blows the experimentation door wide open! Thank you once again for sharing your project with us.

Click here to check out all of Tom’s guest posts and portable adventures!

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Giuseppe discovers his homebrew rotating ferrite antenna works amazingly indoors and nulls RFI

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Many thanks to SWLing Post contributor, Giuseppe Morlè, who writes:

Dear Thomas,

This is Giuseppe Morlè again. First of all, Happy New Year to you and to the whole SWLing Post community! I’ve been continuing the tests on my “T Ferrite” antenna for medium wave and the 160 meters ham meter band.

I tried the antenna inside my shack listening to Rai Radio 1 from Milan Siziano, about 800 km from me, on 900 kHz in the early morning after sunrise. The antenna, despite being inside, proved to be perfect for the cancellation of the electrical noise that I had around me.

Disconnecting the antenna from the receiver–a Sangean ATS-909–the noise occupied everything without being able to listen to anything. Putting the antenna back, the noise disappeared completely making the modulation re-emerge, with a weak signal, it was already day, but with good understandability.

The antenna, as I described in another article, is composed of 2 ferrites 12 cm long each, bought at ham fests, tied together with insulating tape.

For the two windings, I used a small section of cable used for telephone systems that is rigid enough to model perfectly on the ferrites–43 turns for the primary and 3 turns for the coupling link to the receiver. The variable capacitor is 850 pf.

I should mention that the magnificent W1VLF channel was my original source of inspiration for this antenna.

Check out the following video:

Click here to watch on YouTube.

That is amazing, Giuseppe! We often think of magnetic loops as the only choice for coping with urban noise and RFI, but ferrite bars–especially configured like yours–are a brilliant tool for indoor low-band listening. Thank you for sharing! We love your experiments.

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Patrick asks: “Was James Bond a ham radio operator and shortwave listener?”

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Many thanks to SWLing Post contributor, Patrick, who writes:

Many of us have more time during the holiday season to watch good old movies on either streaming services or just old-time DVD. My favourite pastime is to watch James Bond movies, based on the books by Ian Fleming. The iconic British agent in Her Majesty’s service offers insights to technical advancements in different areas.

The other night I was wondering if the fictional character was a licensed ham radio operator and a shortwave listener? First, let me say that he most likely had advanced techniques to master radio communications in several aspects, among them most likely amateur radio and listening to shortwave broadcasts.

In the first movie, Dr. No, (1962), the presence of ham radio or shortwave radio communications is most present, as noted by the SWLing Post blog and we can also get a glimpse of what could be the BBC Monitoring Station. The matter is also discussed by Dr. Bob Heil (K9EID) on YouTube:

But even in other James Bond movies there are different forms of radio communications. In the 1979 movie Moonraker, James Bond confronts the Dr. Holly Goodhead in Venice, Italy, by taking her purse at 01.12.15 in the movie and concludes in what seems to be a shortwave radio with morse that it is standard CIA equipment.

As a commander in the Royal Navy, James Bond would know morse code as well as several aspects of shortwave band. Both at sea but also in his duties as a Secret Service agent operating abroad he most likely listened to BBC World Service and British military radio stations, numbers stations among them, Although we do not know if he carry with him a shortwave receiver or a very small shortwave transceiver. The innovative character of Q probably equipped him with the latest technology.

In the opening scenes of the 1985 movie A View To A Kill James Bond traced a signal with a gadget that looks like a typical yellow Sony Walkman and in the movie The Spy Who Loved me (1977) James Bond receives a message on his watch what seems to be a tape coming out from the watch, telling him to contact the Headquarters.

In the movie Thunderball (1965) at 00.56 James Bond enters a room where a radio operator listening till BBC Overseas programme is listening to a news bulletin with a coded message that Big Ben had strike seven times at six o’clock.

This is fun, Patrick–thanks so much for sharing! Without a doubt, in real life, Cold War era spies used the shortwaves heavily for both receiving and sending coded messages. Indeed, we believe foreign operatives still use the services of numbers stations.

Your message is so timely: I’ve heard from both family and friends recently who are on a bit of a James Bond binge!

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