Category Archives: AM

Coastal DXing with the AirSpy HF+ Discovery and a homebrew passive loop antenna

Last week, we packed the car and headed to coast of South Carolina.

The trip was a bit impromptu but through the creative use of hotel points, we scored a two bedroom ocean front unit with a fantastic little balcony.

The vacation gave me an excuse to test the new passive loop antenna my buddy Vlado (N3CZ) helped me build recently.

The loop design came from AirSpy’s engineer and president, Youssef Touil.

This passive mag loop takes advantage of the new AirSpy HF+ Discovery‘s exceptionally high dynamic range. Youssef had reported impressive results, so I had to build one.

Vlado had a length of Wireman Flexi 4XL that was ideal for this project. The only tricky part was penetrating the shielding and dielectric core at the bottom of the loop, then tapping into both sides of the center conductor for the balun connections. Being Vlado, he used several lengths of heat shrink tubing to make a nice, clean and snag-free design.

The results were truly exceptional. I spent most of my time on mediumwave from the hotel balcony because I was determined to catch a transatlantic signal.

Check out the spectrum display from my Microsoft Surface Go tablet:

Our ocean front hotel was inundated with noise, but I still managed to null out most of it and maximize reception using the passive loop. I simply suspended the loop on the balcony rocking chair–not ideal, but effective and low-profile.

Want to take a test drive?

If you’d like to experience this portable SDR setup, why not tune through one of the spectrum recordings I made?

Click here to download the spectrum file [1.7GB .wav].

The recording was made on November 17, 2019 starting around 01:55 UTC–I chose it at random and have yet to listen to it myself. You’ll need to open this file in AirSpy’s application SDR# or a third party SDR app that can read AirSpy .wav files.

Stay tuned…

I’m writing an in-depth report of the HF+ Discovery, my experiments with this setup and AirSpy’s soon-to-be-released passive loop antenna for the January 2020 issue The Spectrum Monitor magazine. Spoiler alert: I am truly impressed with the wee little AirSpy HF+ Discovery. It’s a powerhouse!

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FCC proposes allowing AM stations to go all-digital

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(Source: Radio Insight)

The FCC approved today the adoption of a rulemaking allowing AM stations to transition to all-digital operation.

Hubbard Radio’s “The Gamut” 820 WWFD Frederick MD has been operating in all digital mode since July 16, 2018 in collaboration with HD Radio owner Xperi. The new rulemaking will allow AM stations to go all-digital and establish operating parameters for doing so.

The FCC today also is opening a comment period on the removal of the programming duplication rule adopted in 1992. The rule limits AM or FM stations from airing more than 25% of total hours in an average broadcast week of duplicative programming. The rule applies to commercial stations in the same service (AM or FM) with substantial contour overlap that are commonlyowned or subject to a time brokerage agreement.[…]

Click here to read the full article.

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AM radio from a hand-wound coil and an oxidized British penny

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Many thanks to SWLing Post contributor, Paul Evans, who shares the following video and article via Hackaday:

There’s been a spate of apocalypse related articles over the last few weeks, but when I saw an AM radio made from a hand-wound coil and an oxidized British penny, I couldn’t help but be impressed. We’ve covered foxhole radios, stereotypical radios that are cobbled together from found parts during wartime.

This example uses a variable capacitor for tuning, but that’s technically optional. All that’s really needed is a coil and something to work as a diode. Surprisingly, copper oxide is a semiconductor, and the surface oxidation on a penny is enough to form a rudimentary diode.[…]

Click here to read the full article at Hackaday.

Thanks for sharing this, Paul. I absolutely love simple receivers like this one. In the past, I’ve built several crystal radios and had great success hearing local AM broadcasters. Indeed, the very first kit I ever built was a crystal radio, then later a foxhole style receiver.

Post readers: Have you ever built a radio similar to this one that uses an oxidized penny? Please comment!

Click here to read posts from our archives that focus on crystal radios.

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The new HanRongDa K-603 portable radio

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Many thanks to SWLing Post contributor, Mei Tao, who writes:

Yesterday, I received a new radio: the HanRongDa K-603, which was sent to me by the manufacture.They want me to test this prototype machine in order to find any bugs. If there is nothing to fix, I believe this radio will hit the market in this or next month.

K-603 is a small portable radio which also has some great functions. Its major features include:

FM, AM, and SW bands

Bluetooth 5.0 connection

TF Card Player

Recording function

Line in

LCD can display three different languages,English?Chinese and another foreign language.

Powered by the BL-5C Li battery

MW channnel space can be switched between 9KHz adn 10KHz.

Tuning methods: Scan, ATS, and direct key entry

The designer told me that this K-603’s fm coverage is from 87MHz to 108MHz, but they will extend it to 64MHz in the next version. That’s really good news.

In a few days, I will test it carefully. If necessary, I will make side-by-side comparisons with my own Tecsun, Sangean, Radiwow, and Degen radios. Then i will present some text and video reviews.

I would like to share some pictures of this new radio with you and other BCLers

Best wishes to you!

Photos

Thank you, Mei Tao! We look forward to your review of the HanRongDa K-603. Yes, please let us know how it compares to your other receivers. We also look forward to any update regarding price and availability. Thanks for sharing those photos!

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The Sony ICF-7600A at my “happy place”

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Yesterday afternoon, the family and I spent some time at my happy place: Mount Mitchell State Park. This might be our last visit there until spring of 2020 since the Blue Ridge Parkway is often closed during the winter.

Yesterday was unseasonably warm at 48F (9C)–a shot of warm weather before an Arctic front moves in tonight dropping temps to about 10F (-12C) and, likely, dropping 1-3″ of snow as well.

The afternoon at Mount Mitchell gave me a little time to play radio, of course, and put my recently acquired Sony ICF-7600A on the air.

How did I acquire the Sony ICF-7600A? Via the generosity of SWLing Post reader, Ed Earps.

Ed reached out to me after I made the following comment in a recent post:

“The ICF-7600A is a cool analog portable and one I’ve thought about acquiring at some point.”

Ed contacted me immediately:

“Thomas, if you would still like to acquire a ICF-7600A, I have one I would give you. This would be in appreciation of all the work you do in writing the SWLing Post blog.”

A few days later, the ICF-7600A with original box and accessories arrived. Wow!

Thank you so much, Ed! Over the years, members of the SWLing Post community have been so kind and so generous, it makes a guy feel humbled and appreciated. Thank you!

The ICF-7600A fits perfectly in my Red Oxx Hound pack.

I’m loving the ICF-7600A.

There’s something so authentic about tuning a good analog portable. It’s hard for me to describe, but I can certainly say it always takes me back to my radio roots.

The ICF-7600A has a low noise floor and seems to be incredibly sensitive. I easily snagged several stations on 31 meters, but ended up enjoying music via All India Radio while brewing a little coffee with my alcohol stove (handmade by my buddy, Greg–thanks, Greg!).

Hey, when you’re a coffee snob, you brew where you are!

But I digress…

I’m especially impressed with the ICF-7600A’s mediumwave performance. I logged a number of benchmark daytime and greyline stations yesterday. I haven’t opened the ‘7600A, but I imagine it has a decent ferrite bar inside based on its overall performance on the AM broadcast band and its nulling capabilities.

Next time, I’ll bring the AN200 mag loop and couple it with the ‘7600A. I’m pretty sure that’ll make for a winning combo.

All-in-all, I couldn’t have asked for a better day: the weather was wonderful, the coffee freshly-brewed, and the gifted ICF-7600A was the perfect radio companion as our family soaked in the scenery after a hike to the summit.

I couldn’t ask for a better happy place!

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FCC to consider allowing AM broadcasters to transition to digital

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(Source: Radio World)

All-Digital on the AM Band? The FCC Might Allow It Soon

AM radio station operators in the United States may soon have the option of switching their transmissions to all-digital.

It’s not a done deal; but the concept is about to take a step closer to reality, because the Federal Communications Commission will consider a proposal at its next meeting that would start a process. It will take comments on whether to allow AM band licensees to make the switch if they want.

Ben Downs, VP/GM of Bryan Broadcasting in Texas, petitioned the FCC in March to initiate a proceeding to authorize the all-digital mode of HD Radio.

Allowing stations to use all-digital transmission is an idea that some broadcasters feel could give business-challenged AM stations in the United States new life or at least another option. Turning off their analog signals would mean that most existing receivers could no longer pick up that signal; but many AM broadcasters are currently heard on FM translator simulcasts now. And adding the all-digital AM option could open up new possibilities for them as the number of digital receivers in the marketplace continues to grow.

[…]Chairman Ajit Pai described the proposal in a blog post Monday: “Just as the FCC is trying to keep pace with changes in the market, so are AM radio operators, and the commission wants to give them as much flexibility as possible to compete in the digital age,” Pai wrote.[…]

Read the full article at Radio World.

Click here to read the proposal (PDF) that will be discussed at the November FCC meeting.

The Radio World article mentions WWFD in Frederick, MD–a station that has been broadcasting AM digital for over a year. We posted a note about this last year and I even included a short recording/video with reception when traveling through the area.

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Jack’s Mediumwave Lazy Susan Mag Loop System

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Many thanks to SWLing Post contributor, Jack Blanke (WB5LVP), who writes:

I stole this idea from another SWLing Post contributor and I hope he won’t mind.

However, placing the Ferrite Antenna near the center of the loop does enhance its performance and the Lazy Susan was something I had been using long ago to quickly re-orient the radio azmuth to accommodate the signal source. But, like my mentor, minor improvements like this can really enhance performance of smaller portables on medium wave. He used cardboard and I used scrap wood from the work shop. Either way, not much money was involved in this minor enhancement.

These inexpensive additions to the listening post really make the PL380 and the AN200 combo provide hours of enjoyment from medium wave DXing. Now,if only I can find the gent’s name who came up with this little gizmo, I’d love to thank him!!

73’s!

Thanks for sharing your setup, Jack! I can assure you that Rich Stahl (WR3V) will be happy you “stole” his idea. That’s what it’s all about–helping each other! I love the little table/stand you built for the portable and how it perfectly accommodates the loop. Great job!