Category Archives: Articles

SWLing Post, Number 2,000

This morning, I noticed that we’ve crossed a small milestone here at the SWLing Post: as of this post, there are now 2,000 published posts in our archives.

It’s a bit incredible that it’s already been almost seven years since I started this blog. In the beginning, I had no aspirations for the SWLing Post to become a popular destination for shortwave and amateur radio enthusiasts; it was mainly a site where I could jot down things I found of interest to me and keep tabs on the radio and international broadcasting industry. I was simply making my bookmarks and thoughts public, perhaps a little in advance of the social media outlets that now exist for shortwave radio and related topics.

A couple of months after starting the SWLing Post, I began using Google Analytics to track readership. I was absolutely floored to discover that, after a year or two online, I had about 200 pageviews per day–meaning, our website guests were reading about 200 pages/posts of information per day! It seemed surreal.

Each year–indeed, each month–that number grew. Now, it’s hard for me to believe the site has about 5,500 daily pageviews. Per month? We’re up to 167,000. As of today, here’s what Google Analytics gives for our monthly figures:

SWLingPost-Numbers

The thing is, these numbers continue to grow.

Best of all, what does this say–loud and clear!–about these “dying” radio shortwaves, about this old and washed-up medium of communication–? It says to us: interest in this hobby is far from dead, but rather, is still alive and well…and perhaps even growing.

And the very best part about hosting the SWLing Post? The community it’s created. So:

Thanks to everyone who makes this possible–to all of those who create guest posts, to those who comment, and to those who help other readers; thanks to those who participate in and moderate the chat room. Thanks to the readers who follow, to the SWLers who listen, to all those who care about radio. Thanks to you all…for the camaraderie, the coffee, the chance to enjoy the growing company of so many readers and fellow-listeners from all around the globe…I am now, and will remain, most humbly grateful.

And to extend my thanks, I’m looking into hosting a forum here on the SWLing Post which should allow for even more interaction within the community. So, yet again, allow me to say: Stay tuned!

There’s even more to come.

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Guest Post: Joris’ home brew Si4835-based receiver

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Many thanks to Joris van Scheindelen (PE1KTH)–an SWLing Post contributor from the Netherlands–for the following guest post:

High Tech AM-FM DSP Receiver From

The old mode AM is still an interesting mode for amateur radio communication, also in amplitude CW.

Building your receiver is not difficult and quite fun. The semiconductor industry makes interesting integrated receiver chips today that will be useful for an AM receiver. Not only for broadcast reception but also for amateur AM reception or as part of an AM transceiver.

Silicon Labs also makes Si4734/35 receivers; these need a CPU to control the receiver, but are of interest for amateur use because the frequency can be tuned in 1 KHz steps and the audio channel bandwidth in 7 steps. There is no need for the transmitter to be on the receiving channel…

Si4835 AM-FM receiver

Looking for a small SW broadcast receiver design, and pocket size, I came to the excellent range of modern DSP receivers in a single chip from Slicon Labs.

I made a test bed set up has been made for the Si4835 AM-FM receiver.

The target specification was:

minimal components,
no micro-controller,
low power,
backlash free mechanical tuning,
good sensitivity,
earphone,
robust housing,
a short and small antenna system for outdoor use,
and minimal controls.

The Si4835 makes miniature design possible on a PCB (see photo Figure 1).

The red Dip (band) switch was replaced by a rotary switch in the final receiver design (Figure 4).

The receiver power is minimal 2 x 1.2 = 2.4 volts or a one cell LI-ION accu.
5 volts is the maximum for the Si4835 chip; current consumption is 30 mA.

Fig 1. Testbed setup for the Si4835.

The receiver has an RF pre-amplifier transistor and the LF amplifier is the TDA7050T.
All receiver functions are in the chip; the schematic is very simple and can be built with minimal components (see schematic appnote AN555 Fig 2. below).

Only an LF amplifier has to be added to complete the receiver.

Fig 2. Receiver schematic Si4835 in the AN555 application note.

The Si4835 receiver has the following frequency bands–they are divided in sub bands 800 or 900 KHz wide (See Figure 3). The frequency step tuning is 10 kHz on AM, following the international broadcast raster standard.

Fig 3. Si4835 receiver sub bands.

This means there are 80 or 90 receive channels in the sub bands and make finding the BC stations on the scale more easy. The 10 KHz scale steps are linear. The frequency stability is locked to the 32 kHz X-tal via the synthesizer so there is no frequency drift. The AM LF audio channel is 5 kHz wide set by the DSP filter. Volume control can be done width 2 up-down push switches or by a LF potentiometer..

Fig 4. The experimental pocket aluminium receiver housing on PCB2.

Receiving results

I have been testing many hours and I am surprised about this little receiver.

The receiving results are excellent on FM and AM and signals of 2 -3 uV are well received.

Also the audio quality is good–especially on FM. As can be seen in the frequency table the 40 and 20 meter band are in the range. Clear AM phone amateur transmission has been received when the transmitter was tuned on the 10 kHz raster in 40 meter band on AM.

Also AM modulated CW signals can be received bud not un-modulated carrier CW–they sound “plop…plop”.

The 5 kHz wide LF channel is a bid too wide so many CW signals pass through the audio at the time, but if AM modulated that should not be a serious problem.

The broadcast stations in the SW bands (when the daytime conditions are good) up to 20 MHz are good and strong.

Conclusions

The Si4835 receiver can be a fine broadcast receiver for outdoor work and if an AM transmitter is tuned in the 10 kHz raster this receiver can also used for amateur phone reception.

Addendum: The Si4734/35 is a better amateur AM Receiver

The Si4734 and Si4735 are a better receiver choice for amateur AM purpose because the frequency tuning can be done in 1 kHz steps. Also the BW of the LF channel can be adjusted to 1 kHz wide.

In Fig 5. from the programming APP note you see the code 0X3102 AM CHANNEL_FILTER it is possible to adjust the audio width by sending this code to the Si4734/35.

Fig 5. From the programming APP note

The LF bandwidth can be set on 1, 1.8, 2.5, 2, 3, 4 and 6 kHz wide.

This is excellent for modulated CW and AM phone discrimination in the audio channel.

The disadvantage is the need of an CPU and LCD display, “away from a minimalistic design”.

See also the note 1 and 2 improved 100 Hz rejection. See data sheet of the Si4734/35.

It look like that this receiver is a good receiver for building a modern AM-(AM)CW receiver or in a transceiver application. Tuning can be done digitally.

Think about this receiver [and the Si4835 chipset] when you intent to build a high tech AM – T/RX.

73 ‘ Joris van Scheindelen PE1KTH

What a fantastic home-brew receiver, Joris! I love the simple design of your receiver and the fact that it’s quite portable. Thanks so much for sharing your notes and documentation.

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A repair story: Vlado’s fix for the classic Sony ICF-SW100

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In June, I made a small leap of faith and purchased a (dead) Sony ICF-SW100 from Universal Radio (see the listing on right).

ICF-SW100-Used-NonWorking You see, for many years, I’ve dreamed about owning this wee little receiver, now a classic among tiny radios, but used ones are typically too expensive for my modest budget.

This time, seeing the ad at Universal, I spoke with Universal Radio directly to obtain more details about their defunct unit; while they simply didn’t know what was wrong with the Sony, they were able to very accurately describe its cosmetic and functional condition…I took a deep breath, and decided to take a chance on it anyhow.

In full disclosure, I have a secret weapon in my camp: my talented friend, Vlado (N3CZ), who is not only the most adept electronics engineer/technician I’ve ever known, but one who truly welcomes a challenge. The thought had occurred to me as I admired the wounded Sony, Wonder if Vlad would like to take this on–?

The answer, of course, was Yes! So I dropped the DOA Sony off at Vlad’s home last week. He disassembled the radio, only to discover that my ICF-SW100 was a victim of the (dreaded) damaged ribbon cable.

A short history of the Sony ICF-SW100 and SW100S

These radios are indeed brilliant, incredible performers for their miniscule size. Yet the first generation of ICF-SW100 radios–those produced before the fall of 1997–have a design weakness: the ribbon cables which connect the upper and lower portions of the radio’s clamshell design eventually fail. Multiple openings and closings bend and cut the cables, rendering the otherwise remarkable little radio useless.

SWLing Post contributor, Dan Robinson, recently shared his knowledge about the ICF-SW100 series. Dan notes:

SW-100 Seekers Beware

As shortwave veterans know, the classic SONY miniportables — SW-1, SW-100(S) and SW-07, represented some amazing technological achievements. SONY managed to shrink some fantastic technology into these receivers, including (with the last two in the line) — SYNC capability. The SW-07, which was the last of these receivers, still brings some high prices on Ebay.

But if you are searching for the ICF-SW-100S there are some things to consider and beware of. As everyone knows, the SW-100 suffered from the well-known ribbon-cable failure problem. SONY addressed this problem in later serial numbers, and changed the design of the radio case.

Modified SW-100s have a notch where the top cover meets the base.

There are some dishonest sellers out there who are trying to pass off older version SW-100s as modified ones. Usually, the tip-off is that the photograph in the Ebay auction will be dark or out of focus, so it’s hard to tell if the radio is the modified version or not.

It has become quite rare to find an original SONY modification kit, which includes a new top cabinet of the SW-100. And some sellers are trying to get as much as $300 for these, though they rarely sell at this level.

This repair kit was on eBay at time of posting.

ICF-SW100 modification kit found on eBay at time of posting.

It’s also becoming rare to see SW-100S radios new-in-box. I had two of these, sold one and kept the other.

If you’re after one of these marvel radios, do what everyone should do when considering items on Ebay — ask many questions about [the] cosmetic condition, accessories, serial numbers, etc.

Universal Radio, a trustworthy seller I know, had fully disclosed the model number and problems with this radio, so I knew exactly what I was buying. Dan has a very good point, though: unless you know the seller to be honest, do your research and ask questions!

The ailing ICF-SW100

Vlado discovers the faulty ribbon cable (click to enlarge)

Back to my ailing unit: Vlado delivered the news about the ribbon cable via text message, and though I was well aware that the chances were high that was the ribbon cable, I was a little bummed, to say the least, to get the formal diagnosis.

Why? As Dan mentions above, you’ll find that the SW-100S upgrade kit Sony produced in the 1990s is no longer available new; sellers typically list these kits at prices in excess of $300 US. Out of my budget.

But Vlado, ever the intrepid engineer, had no idea I would be disappointed with this news; he was just giving me this FYI via text. Indeed, he seemed entirely unfazed, as in, hey, no serious internal damage here…

Another hour passed. Then came another message from Vlad; this one simply said: “Call me.”

Oh no, I thought. But I called, and Vlado answered cheerfully, “Hello? Tom, is that you? Sorry, I can’t hear you very well because your SW100 is playing too loudly. Hang on–let me turn the volume down!”

Vlad installs the replacement ribbon cable (click to enlarge)

“What!?!” I responded, in utter disbelief.

Yes, he’d got it working! It seems that Vlad had unearthed an old DVD player in his garage that he’d kept merely for parts. He opened it up, identified a ribbon cable with the right pitch, then cut and folded the cable to fit into the SW100. Ingenious!

That’s Vlado for you!

And should I be interested in replacing this used cable with a new one–or in repairing other Sonys–Vlad directed me to eBay listings for new cables which only total about $20, shipped. Truthfully, I’m in no hurry, as this one is functioning perfectly and changing out the ribbon cable seems to have no effect on stored memories, etc. With a single affordable eBay purchase of multiple cable sets, it occurred to me that Vlad would have enough replacement cables to repair the SW100 many times over…

So I bought the cables. (This one for the narrow cable and this one for the wider one.)

My “new” Sony ICF-SW100

Needless to say, I’m very pleased with my “new” (to me) SW100. It’s a little masterpiece of receiver engineering in such a tiny package. And since the ICF-SW100 is unquestionably the smallest portable I own–and is one of the few I own with a proper line-out jack–it may very well become my go-to radio for one bag travel.

It’s in the bag: listening to the ‘SW100 before I pack it for my next trip!

Stay tuned the review…

Vlado’s radio E.R.: the doctor is in

As I’ve said, Vlad is one of the most adept repair technicians I’ve ever known. At my prompting, he’s kindly agreed to let me promote his services here on the SWLing Post. Vlad acknowledges that he “likes a challenge,” adding that he enjoys nothing more than making repairs even when”parts are scarce” and radio”surgery” is required. Moreover, his bench fees will be quite reasonable, especially considering what you receive: new life for a failing radio. So, if you’ve got an ailing rig on your hands, and don’t mind waiting for Vlad to get to it, send it to his radio emergency room, where radios (like my Sony) have life breathed back into them once again.

Long live the Sony ICF-SW100! And long live Dr. Vlado, who makes this possible with his creative (and nearly miraculous) repairs.

To contact Vlad, simply contact me with a description of your radio and its problem and I’ll put you in touch with Vlado.

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Guest Post: Richard tests the frequency stability of the Tecsun PL-880

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Many thanks to SWLing Post contributor, Richard Langley, for the following guest post:

Frequency Stability of My Tecsun PL-880

Recently, while recording the audio on a particular SW frequency unattended over night, I decided to set my Tecsun PL-880 in USB mode with the 3.5 kHz RF bandwidth setting as I had previously noticed splatter QRM from a station 10 kHz below my frequency of interest. I adjusted the frequency to the nearest 10 Hz for natural-sounding voice. On playing the recording, I was disappointed to find that the signal had drifted in frequency and although speech was still recognizable, music was distorted.

I decided to try to measure the stability of the receiver by recording the Canadian time signal station CHU on 7850.00 kHz in USB mode (CHU has no LSB component) over night for over nine hours. The receiver was operated with just its telescopic whip antenna indoors and the audio was recorded with a Tecsun ICR-100 radio recorder / digital audio player. I wrote a Python script to compute the audio spectrum of each one-minute segment of the recorded files using a fast Fourier transform (after removing a DC component). The script then looks for the largest peaks in the spectra centred on a specified frequency and prints out the frequency (to the nearest Hz) and amplitude of the peak. In case the signal has dropped below audibility, a threshold is set and if the detected peak is below the threshold (likely just detecting the random noise background), it is skipped. The specific centre frequency I was looking for was 1000 Hz, the frequency of the tone used to mark each second of the CHU broadcast except when the voice announcement and digital signal are transmitted. In AM mode, the spectrum would consistently show a peak at 1000 Hz but in SSB mode, the peak will vary depending on the receiver frequency setting and the actual frequency of the receiver’s oscillator.

The plot below shows the received CHU one-second tone frequency as a function of time (UTC) from when the receiver was first switched on.

StabilityPlot-CHU1000hz

It shows the tone frequency started out at about 1046 Hz slowly dropping in the first half hour to about 1012 Hz and after about an hour stabilized to 1011 Hz ± 1 Hz for the better part of an hour. (This shows that you may have to allow a receiver to “warm up” for perhaps up to an hour before attempting anything close to accurate frequency reading at the order of 10 Hz.) But then, over the course of the next seven hours when the signal was audible, the frequency slowly rose ending up at about 1034 Hz. The variation might be affected by the ambient air temperature (but this should have been nearly constant), air flow around the receiver, and perhaps the charge level of the receiver’s battery. On several occasions, I have turned the receiver on (after being off for many hours) and seen a CHU frequency offset of only 10 or 20 Hz. So, I intend to repeat this experiment sometime to check on the day-to-day frequency stability. This frequency stability measurement technique could also be used with WWV/WWVH by recording the 440, 500, or 600 Hz tones broadcast at different times during the broadcast hour.

Of course, it’s also possible to check the receiver’s frequency offset in real time by switching between AM and SSB modes while adjusting the receiver frequency in 10 Hz steps until the signal sounds the same in both modes. There is also freely available computer software for various operating systems that can display a real-time spectrum of audio passed to it through a microphone or line input. So, a CHU or WWV/WWVH test using such software could also be performed in real time. And alternatively, by tuning say exactly 1 kHz away from the transmitted carrier frequency in SSB mode, the software can be used to measure the audible heterodyne frequency to better than 10 Hz — even 1 Hz. This frequency can then be added or subtracted as appropriate to the dial reading (assumed accurate or with a noted offset) to get the exact transmitted carrier frequency.

By the way, it is possible to calibrate and reset the PL-880 using the procedure documented on the SWLing Post (click here to view).

As a side benefit of the analysis I carried out, we can also look at the quality of the received signal over the recorded interval. In this case, it is a measure of the level of a particular audio frequency rather than the RF signal+noise level we usually get from the receiver S-meter or other signal strength display. This is illustrated in the plot below for the CHU recording. As you can see, reception was mostly quite good between about 02:00 and 04:00 UTC and then became fair but above threshold level until about 05:30 UTC.

The signal was then essentially inaudible up to about 08:00 UTC when with bouts of fading it became audible again for an hour or two with sunrise approaching.

— Richard Langley

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Dr. Phil’s radio articles: portable SDR and pocket DX

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SWLing Post reader, Dr. Phil, recently contacted me regarding a collection of articles he’s written about DXing and radio modifications.

His site actually has a number of useful articles that I’ll plan to convert to future posts, with his permission.

I asked Dr. Phil for links to two of his most popular publications. He replied:

My two big recent articles are shown below. One is about “Pocket Radio DX”: using under-$20 radios to DX (started in 2003). Click here to download as a PDF.

The other is about using an $18 NooElec TV-tuner as a MW and shortwave receiver. Click here to download as a PDF.

Brilliant! Thanks so much for sharing these, Dr. Phil!

I actually have a Sony ICF-S10MK2, which I consider to be a capable and useful little AM/FM receiver for the sub $20 price. I’ve also been very tempted to purchase an RTL-SDR dongle, so I may go ahead and bite the bullet on one of the NooElec SDR dongles.

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The WSJ features Willis Conover

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(Source: Wall Street Journal via Any Sennitt)

The Radio Broadcaster Who Fought the Cold War Abroad but Remained Unheard at Home

By DOUG RAMSEY

During the Cold War, listeners in captive nations behind the Iron Curtain huddled around radios in basements and attics listening to the imposing bass-baritone voice of the man who sent them American music. His greeting—“Good evening, Willis Conover in Washington, D.C., with Music U.S.A.”—was familiar to millions around the world. At home, relatively few people knew him or his work. A proposal for a postage stamp honoring Conover may give hope to those who want the late Voice of America broadcaster to be awarded a larger mark of distinction.

For 40 years, until shortly before his death in 1996, Conover’s shortwave broadcasts on the Voice of America constituted one of his country’s most effective instruments of cultural diplomacy. Never a government employee, to maintain his independence he worked as a freelance contractor. With knowledge, taste, dignity and no tinge of politics, he introduced his listeners to jazz and American popular music. He interviewed virtually every prominent jazz figure of the second half of the 20th century. His use of the VOA’s “special English”—simple vocabulary and structures spoken at a slow tempo—made him, in effect, a teacher of the language to his listeners.

Countless musicians from former Iron Curtain countries have credited Conover with attracting them to jazz, among them the Czech bassists George Mraz and Miroslav Vitous, the Cuban saxophonist and clarinetist Paquito D’Rivera and the Russian trumpeter Valery Ponomarev. On the Conover Facebook page established in 2010, Ponomarev wrote that Conover had done as much for jazz “as Art Blakey, Duke Ellington, Horace Silver, Count Basie, Charlie Parker, Miles Davis and Dizzy Gillespie.” Conover’s New York Times obituary said, “In the long struggle between the forces of Communism and democracy, Mr. Conover, who went on the air in 1955 . . . proved more effective than a fleet of B-29’s.” In his publication Gene Lees Jazzletter, the influential critic wrote, “Willis Conover did more to crumble the Berlin Wall and bring about the collapse of the Soviet Empire than all the Cold War presidents put together.”[…]

Continue reading at the Wall Street Journal…

Regular SWLing Post readers know that I’m a huge fan of Willis Conover. Much like VOA’s Leo Sarkisian, Conover represented some of the best diplomacy this country has had to offer. [I’ve actually had the honor of meeting and interviewing Leo Sarkisian at his home in Maryland, a few years ago–one of the highlights of my career.]

Are there any SWLing Post readers out there who listened to Willis Conover from behind the “Iron Curtain?” Please comment!

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Radio Cook Islands: Guy’s 1993 recordings

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Many thanks to SWLing Post contributor, Guy Atkins, for the following guest post:

Radio Cook Islands

by Guy Atkins

A view from the driveway entrance to the Radio Cook Islands studio in 1993. Insulators on an antenna (T2FD or multiband dipole) can be seen as dark spots against the cloudy sky. A feedline is also seen rising above the left side of the building. (Photo: Guy Atkins)

(Photo: Universal Radio)

In 1993 I was fortunate to have the opportunity to visit Rarotonga with my wife, courtesy of a nice award through my company which afforded me an all-expenses-paid trip anywhere we’d like to go.

I chose the South Pacific island of Rarotonga, partly because I wanted to visit Radio Cook Islands after listening to their “island music” on 11760 and 15170 kHz through my teenage years.

During our visit to the island I recorded 90+ minutes of RCI on 630 kHz with a local quality signal using a Grundig Satellit 500 and a Marantz PMD-221 recorder.

Recordings

The programming of Radio Cook Islands is bilingual, and announcers are fluent in both English and Cook Islands Maori. Music selections on RCI encompass all styles, to appeal to many age groups. These recordings was scheduled to include as much local music as possible.

RCI programming includes all the hallmarks of a small, non-professional station: stuck records & tape carts, dead air, poor modulation, and other miscues.

However, that’s part of the flavor of local radio, and these errors are heard throughout this recording. Particularly noticeable is the bassy, over-modulation of the studio announcer during sign-on announcements.

Recording 1

Notes: National anthem & hymn; sign-on announcements & music.
Music; weather; sign-off announcements & national anthem.
Local & regional news; weather; ads; music.

Recording 2

Notes: “Party Time” music request show; weather; local ads; more music.

Two engineers from Radio Cook Islands, photographed during my visit in April, 1993. (Photo: Guy Atkins)

Sadly, RCI will likely never be on shortwave again; a fire in the local tele-comm building a few months before my 1993 visit destroyed RCI’s transmitter. I had an amusing exchange with the secretary when I visited; she insisted that their station was still on shortwave. Of COURSE we’re on the air she said, because “the frequencies are published right here in the newspaper!” The engineer and announcer confirmed, though, that the silence on their former frequencies was for real. They indicated they were covering the outer islands just fine with FM translators and had no intention of restarting shortwave.

Radio Cook Islands 630 kHz antenna on the school ground of Takitumu Primary School.

RCI’s headquarters is in downtown Avarua, and their 5 kw transmitter (reported at half power, 2.5 kw in Dec. 2012) and modern quarter-wavelength vertical antenna is located in the town of Matavera (northeast side of Rarotonga).

Bing.com maps view of Radio Cook Islands antenna, 630 kHz at Takitumu Primary School, Matavera.

The antenna is in the yard of Takitumu primary school; see photos from Bing Maps and Panaromio [above].

It sure brings back a flood of good memories when I listen to these MP3s! I’d love to visit the Cooks again sometime.

Many thanks for this wonderful stroll down memory lane, Guy–radio nostalgia at its best!

I, too, would love to visit the Cook Islands someday–it is on my bucket list. In the meantime, I’ll enjoy your recordings. Again, many thanks for your guest post!

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