The Oxo Good Grips Turntable for the Mediumwave DXer

SWLing Post contributor, Robert Gulley, writes:

I recently purchased an Oxo Good Grips Turntable, 16” from Amazon. As the photos show, the size of the turntable can hold a fairly large radio (CC Radio EP and Select-a-tenna) on the turntable in almost any configuration. (Of course the CC Radio EP doesn’t need the Select-a-tenna, just used for illustration purposes for size.)

At $16.99 I think it is a good bargain, and seems quite capable of turning smoothly even with this amount of weight.

Click here to view on Amazon.com.

Many thanks, Robert! I think that turntable is large enough to hold pretty much any portable radio; thanks so much for the photos (especially the one your kitty cat photo bombed, above!). I have several OXO products in my kitchen and have never been disappointed with quality, so I expect this turntable will last you a very long time.

Readers: If you haven’t checked out Robert’s radio blog, All Things Radio, I encourage you to do so!

Could radio be a catalyst for revolution in North Korea?

1 Reply

Many thanks to SWLing Post contributor, Richard Langley for sharing this article from The Guardian. The following is an excerpt:

Kim Cheol-su, who was born in Pyongsong City and defected from North Korea last year, says that up to 30-40% of DPRK citizens now listen to pirate radio, and that listening to the broadcasts made him realise the true nature of Kim Jong-un’s dictatorship.

Speaking at a roundtable discussion on the implications of the broadcasts in Seoul – and of the North’s thundering reaction – he said: “Children know that Kim Jong-un weighs more than 100kg. It’s because they are repeating what they hear from their parents, who listen to these foreign programmes.”

He added that the majority of North Korean citizens, desperate for news of the outside world, listen to the propaganda broadcasts which fan the flames of their doubt about the regime. The majority of those who flee to the South do so after hearing the broadcasts, he claimed.

“Before listening to the broadcasts, the citizens have no idea. But after they hear them, they realise the fact that the regime is deceiving people. They share what they have heard with their neighbours and friends.”

Kim also highlighted the fact that he heard about the Arab Spring movement through the broadcasts, and learned of the death of Libya’s former president, Muammar Gaddafi. “If the UN were to guarantee for us, as they did for Libya, help in opposing the regime, I believe that we would revolt as well,” he said.

Kim said lot of people listen to Radio Free Asia, as it comes in the clearest. “Personally, there were some programmes I liked on Open Radio for North Korea, so I used to tune in to those as well. However, short, one-hour programs were easy to miss. They were often finished by the time I found the frequency they were on.”

As for the contents of the broadcasts, Kim said having defectors talk freely about their lives was the best approach, and that programmes should include information on how to defect, offering examples of the kind of support and policies that exist for defectors in the South.

Read the full article at The Guardian online.

SWLing Post, Number 2,000

13 Replies

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.

Guest Post: Joris’ home brew Si4835-based receiver

3 Replies

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.

Shortwave Radio Recordings: Radio Spaceshuttle International

1 Reply

SWLing Post and SRAA contributor, Jim Clary (ND9M/VQ9JC), recorded the following final broadcast of Radio Spaceshuttle International while on board a US Navy ship off the coast of Rota, Spain. Jim notes:

I was packing up to leave my ship and return to the USA this week when the latest SWLing Post e-mail showed up with info about SSR’s final broadcast literally seven minutes before he was to come on the air. I’d already broken down the receiving gear, but it came back together in record time, and I was able to get the recorder going with a minute before the transmission started.

Click here to download Jim’s recording as an MP3, or simply listen via the embedded player below. Note that Jim’s recording starts a few minutes before the broadcast begins:

Audio Player

00:00

Use Up/Down Arrow keys to increase or decrease volume.

Jim, thanks so much for putting all of your receiver and recording kit back together to make this recording!

Kim Elliott on shortwave radios & signal jamming in 2015

6 Replies

(Source: USC Center on Public Diplomacy)

BBC Russian Wants to Expand, But It’s Not So Easy

The BBC, as part of its 2015 Charter Review document, announced proposals to “invest” in BBC World Service. This includes a desire for a “bigger digital presence in Russian through a new digital service on platforms such as YouTube and the Russian equivalent Rutube, together with TV bulletins for neighbouring states. We would also start a feasibility study for a satellite TV channel for Russia.”

[…]The feasibility of BBC satellite TV for Russia is problematic. Very few Russians have rotatable satellite dishes, surfing the Clarke Belt in search of outside news. About 25% of Russian homes have fixed Ku-band satellite dishes to receive proprietary domestic direct-to-home services such as TricolorTV and NTV+. Western Russian-language news channels are not included in these channel packages and are unlikely to be invited aboard. Content from Western Russian-language broadcasters, including Voice of America and Radio Liberty, is also legally not welcome on Russian domestic terrestrial television and radio stations.

[…]So far, Russia has not blocked the Internet content of Western international broadcasters, at least not on a continuous basis. The Kremlin’s repeated denials of any intent to block Internet content suggest that it has at least been thinking about it. And recent press accounts indicate that Russian authorities may even try to ban anonymizers and other methods used to work around online censorship. Circumvention tools would have to become even cleverer, and Russian users would have to be willing and able to use them. In an extreme scenario, Russia could physically cut off the landlines of Internet traffic into the country. Then no circumvention tool within the Internet Protocol would work.

This could bring BBC Russian full circle to the venerable but unfashionable medium of shortwave radio. To be sure, Russians are out of the habit of listening to shortwave. Shortwave is no longer used for domestic broadcasting in Russia. BBC Russian eliminated its shortwave broadcasts in 2011. But, if need be, Russians could dust off their Cold War era shortwave radios. Or they could purchase inexpensive Chinese-made portable radios with shortwave bands.

In addition to traditional voice broadcasts, text, images, and even formatted web pages can now be broadcast using existing shortwave transmitters, and received on any shortwave radio. The audio must be fed to a PC or mobile device equipped with appropriate (free) software. Such a method allows reception of content even in difficult reception conditions, and allows unattended reception. This new capability of existing shortwave broadcast technology has been demonstrated through the VOA Radiogram experiments.

If Russia blocks Internet content from abroad, it will also probably try to jam shortwave radio content from abroad. Most jamming transmitters of the Cold War era have been dismantled or have fallen into disrepair. Many of the jamming transmitters are outside of Russia, in former Soviet republics. Reviving a shortwave jamming apparatus would be a much more expensive proposition than blocking Internet content. Various Cold War anti-jamming tactics, using various tricks of ionospheric propagation, can be employed. Text via shortwave would be even more resistant to jamming than voice broadcasts.[…]

Read the full article by Kim Andrew Elliott at the USC Center on Public Diplomacy online.

Radio Spaceshuttle International: another attempt at a final broadcast

2 Replies

I just received word from Dick at Radio Spaceshuttle International. Last week, they had technical difficulties which prevented them from transmitting their final broadcast.

Fortunately, RSI is making a third(!) attempt to get the show on the air. Dick has informed me that Radio Spaceshuttle International will broadcast tomorrow (Sunday) September 20 from 19:00-20:00 UTC on 13,600 kHz.

By the way, I asked Dick why he was leaving the air. He told me that it’s simply a matter of time–something he has in short supply right now. Will RSI return to the air sometime in the future? Dick responds:

So, I shall not say final goodbyes…. Hopefully Radio Spaceshuttle will return “on some sunny weekend”

Very good. We’ll be listening! Speaking of which, I will make an effort to hear the RSI broadcast tomorrow, State side, if propagation is in my favor.

Let’s hope the third time is the charm!