Author Archives: Thomas

Tecsun PL-990: How to distinguish pilot run and final export versions

The Tecsun PL-990

As I suspected, it appears the Tecsun PL-990 batch that showed up recently on AliExpress for $399 each are the preliminary pilot run units that Tecsun offered in China last year. The final export version of the PL-990 is not ready for production yet and has been severely delayed by Covid-19 quarantines.

Anna at Anon-Co reports that Tecsun factories have been closed since mid-January 2020 and have only recently recommenced production, “but at a very slow pace.”

Since there will eventually be two different versions of the Tecsun PL-990 in the wild–the pilot run for China, and the finalized export version–I thought I’d share a trick Anna has described to tell the difference between the two.

Anna notes:

One way to easily see this is from the labels for the buttons above the keypad, these should be

[ TIME ], [ TIMER A ], and [ TIMER B ] (see picture below)

Tecsun PL-990 Final Export Version:

Tecsun PL-990 Final Export Version

Pilot Tecsun PL-990 (preliminary China domestic version):

Preliminary Pilot Tecsun PL-990 distributed in China — image from AliExpress.

Anna adds:

I highly recommend [no one] buy these pilot versions, because the software on those devices is also not developed.

There still isn’t a final version or any price indication available yet, but it will definitely not be US$399.99.

So in case it’s not clear: don’t purchase a PL-990 until you can confirm you’re receiving a final export version which has the TIME, TIMER A, and TIMER B labels.

Again, at time of posting, the final PL-990 export version is not yet in production.

When the final export PL-990 is available, I will announce it here on the SWLing Post with links to authorized retailers like Anon-Co.

Patreon Code

Do you enjoy the SWLing Post?

Please consider supporting us via Patreon or our Coffee Fund!

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

Free to a good home: A Vintage Grundig Satellit 600 Professional

5 Replies

I was recently contacted by Allan Rosenbluth, a particularly generous SWLing Post reader.

Allan contacted me because he would like to give away his cosmetically excellent Grundig Satellit 600 Professional (see photo above) with all the original paperwork. He said that the radio turns on, but does not work or produce sound. Allan purchased this radio for his father who has sadly passed away.

I would assume the 600 might need to be re-capped, or it might only need a little DeOxit on some of the contacts.

We’re not looking for someone to fix the 600 and flip it on eBay, we would simply like his dad’s Satellit 600 Pro to find a good home.

Allan is not interested in the hassle of shipping this radio–he only want to arrange a local pickup.

If you live near Encino, CA (91436) and are interested, simply contact Allan via his email address.

Thanks again, Allan!

Do you enjoy the SWLing Post?

Please consider supporting us via Patreon or our Coffee Fund!

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

SiriusXM offers channel and free stream devoted to Covid-19 awareness

Airspy Youloop and Homebrew Passive Loop Antenna designs

2 Replies

Almost two weeks ago, at the 2020 Winter SWL Fest, I gave a presentation called “A New Era in Portable SDR DXing.”

The presentation was essentially an in-depth version of an article I published in the January 2020 issue of The Spectrum Monitor magazine (see cover above).

I devoted a good portion of the presentation describing how to build a passive loop antenna design by Airspy’s engineer and president, Youssef Touil. This passive mag loop takes advantage of the Airspy HF+ Discovery‘s exceptionally high dynamic range and is an impressive performer.

The homebrew loop on the balcony of a hotel.

You may recall, I posted a short article about this loop in November after enjoying a little coastal DXing.

In short? This passive loop antenna pairs beautifully with the Airspy HF+ Discovery. I’ve also been very pleased with results using the new SDRplay RSPdx on the mediumwave band where the receiver now sports a high dynamic range mode.

Overdue corrections…

After returning from the Winter SWL Fest last week, I was hit with an upper respiratory bug. No doubt, a souvenir of my travels! It wasn’t the flu (I was tested), nor COVID-19, but it did knock me off my feet for a few days with fever, coughing, and headaches. You might have noticed a lot less posts last week and almost no replies from me via email. I’m only now feeling totally human again and trying to catch up with my backlog.

Shortly after my SWL Fest presentation, I realized I made (at least!) two mistakes. I had planned to post corrections here on the SWLing Post last week, but the bug delayed all of that, so here you go:

#1 Schematic of my homebrew passive loop antenna

When Youssef started experimenting with passive loop antenna designs, he posted a few schematics of at least three build options.

Although I described how to build my passive loop antenna, I grabbed the wrong schematic for my presentation slides. Many thanks to those attendees who noticed this.

Here is the schematic I should have shared:

Note that the transformer has four turns on both sides (the one in the presentation had 4:2).

Again, apologies for any confusion.

#2 The Airspy Youloop passive loop antenna

If you’re not inclined to build your own passive loop antenna per the diagram above, Airspy is planning to manufacture and sell a lightweight, high-performance loop of a similar design.

Prototype of the Airspy Youloop in the field (note bright blue cable jacket)

During the presentation, I called the future AirSpy antenna, the “Spytenna.” I was incorrect. (Turns out, I got this name from an early antenna schematic and somehow it stuck in my head!)

Airspy is calling their passive loop antenna the Youloop. Youssef posted the following note in the Airspy email discussion group:

We are currently arranging the shipping of the affordable passive version to Airspy.us and RTLSDR Blog.

Btw, It’s called “Youloop”

Many thanks to Richard Langley and a number of other readers who pointed this out last week.

I’ve had a prototype of the Youloop since November and brought it to the SWL Fest and presentation. It’s a quality antenna and incredibly compact when disassembled and rolled up.

When the Youloop is available to order, we’ll post links here on the SWLing Post.

More to come!

Once I catch up here at SWLing Post HQ, I plan to publish detailed construction photos of the homebrew loop antenna.

Many of you have questions about how to tap into the center conductor at the mid-point of the loop. These photos should help guide you.

Stay tuned!

Do you enjoy the SWLing Post?

Please consider supporting us via Patreon or our Coffee Fund!

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

Steve’s crusade to obtain KGAF license plate

3 Replies

Many thanks to SWLing Post contributor, Dan Van Hoy, who shares the following item from WFAA:

GAINESVILLE, Texas — A North Texas radio station that the Texas Department of Motor Vehicles determined had call letters that were too “vulgar” to put on a personalized license plate finally has those formerly vulgar letters proudly affixed to its one station vehicle.

It’s a victory thanks to a Gainesville-area lawmaker who decided a bit of common sense was in order.

Late last year KGAF station manager Steve Eberhart started the process, applying to have KGAF on a personalized license plate for their company van. The station has been a fixture in Gainesville since 1947. But in a modern world that sometimes communicates in OMGs, LOLs, IDKs and IMHOs, the state told him that KGAF might mean something, too.

“Well, I’ve been told that it’s an acronym or a slang for social media for ‘can’t give a (expletive),” Eberhart said. “But certainly we never intended that,” he told me several weeks ago. “I can assure you the people in 1947 did not intend for it to mean that!”[…]

Click here for the full story at WFAA.

That is a riot, Dan! Thank you for sharing. I’m glad someone finally came to their senses and gave Steve his plate!

Dean solves second interval signal mystery

5 Replies

(Image source: Madrid.org)

In response to our second mystery interval signal challenge, SWLing Post contributor, Dean Bianco replies:

Mystery solved!

This is the “interval signal” (more accurately, a placeholder with a musical station identifier) for the Compañía Telefónica Nacional de España (CTNW) from Madrid, Spain.

They were a point-to-point HF radiotelephone terminal that provided overseas telephone and telegraph services in the days before satellites became common.

As a young SWL, I would receive all manner of strange musical identifiers for these utility stations. Most of these HF telecommunication services had gone to satellite by the early 1980’s. The HF bands were chock-a-block with signals, whether they be broadcast or utility services.

Glad to help!

To verify his claim, Dean shares the following embedded audio file made by Willi Passmann in the mid 1970s (via the excellent UtilityRadio.com website):

Well done, Dean! Thank you once again for coming to the rescue!

In case you didn’t know, dear readers, Dean Bianco is a force to be reckoned with in the shortwave radio world. 🙂 This year, he won the 3rd Annual Fest Trivia Quiz at the 2020 Winter SWL Fest! An impressive accomplishment, indeed. Not only that, but Dean’s an incredibly nice guy, great friend, and always willing to help out those new to the hobby!

Thank you, Dean!