The Digital Radio Era (Partially) Ends In Ireland

March 7, 2021 by Jenny List 96 Comments

It’s commonly agreed that the future of broadcast radio lies in the eventual replacement of AM and FM analogue transmissions with digital services. A wide range of technologies exist to service this change-over, and for much of the world the most visible of them has been Digital Audio Broadcasting, or DAB. This VHF service has slowly increased in popularity to the extent that in some countries the FM or AM switch-off process has already happened or is well under way. It’s thus a surprise to hear a piece of news from a country that’s going the other way, as the Irish broadcaster RTÉ is about to turn off its national DAB multiplex.

The reason cited is cost-effectiveness, the take up of DAB in the Republic by listeners is low (Northern Ireland having the UK multiplexes instead), and that the broadcaster is the only one maintaining a national multiplex. Our Irish friends tell us that as in other parts of the world the rural coverage can be patchy, and with only RTÉ and no commercial stations on offer it’s easy to see why the allure of a DAB set is lacking.

In case anyone is tempted to prophecy the demise of digital broadcasting from this news, that’s not the real story. This is simply an abandonment of DAB. Plenty of Irish people listen to the radio through digital media just as anywhere else, this is simply an indication that they’re choosing not to do so via DAB. The Irish DVB television multiplexes carry the same stations and more, and meanwhile, the inexorable rise of online listening through smart speakers and mobile phones has eaten DAB’s lunch. But it does raise the point for other places: when your mobile phone delivers any radio station or streaming service you desire and is always in your pocket, why would you want a radio?

For more on DAB including some of its shortcomings, a few years ago we took an in-depth look at the system.

Thanks [Laura] for the header image.

Retrotechtacular: Philips Factory Tour, Circa 1930s

March 3, 2021 by Dan Maloney 34 Comments

If you’ve got a half-hour or so to spare, you could do worse than this video trip through a Philips factory in the 1930s.

The film is presented without narration, but from the Dutch title cards and the fact that it’s Philips, we gather that this factory of gigantic proportions was somewhere in the Netherlands. In any case, it looks like something right out of [Fritz Lang]’s Metropolis and turned the rawest of materials into finished consumer products.

Much of the film focuses on the making of vacuum tubes; the sheer physicality of the job is what really stands out here. The upper body strength that the glassblowers had to have boggles the mind. Check out the chops — and the soon-to-be very unfashionable mustache — on the glassblower at the 12:00 mark. And it wasn’t just the gents who had mad skills — the fine motor control needed for the delicate assembly of the innards of the tubes, which seems to be mostly staffed by women, is just as impressive. We were also surprised by the amount these manual crafts were assisted by automated systems.

Especially interesting is the section where they build the luidspreker. Without narration or captions, it’s a little hard to tell what’s going on, but it appears that they used an enormous press to form chips of Bakelite into sleek covers for the speakers, which themselves are super-chunky affairs made from scratch in the factory. We’re also treated to assembly of the radios, packaging of finished products, and a group of dockworkers who clearly didn’t read the “Fragile” labels pasted on the boxes.

One can’t help but wonder if these people had the slightest inkling of what was about to sweep over them and the rest of the world. And if they did, would they even begin to comprehend how much the very products that they were making would contribute to both the slaughter of the coming war as well as to the sparing of so many lives? Likely not, but the film is still an interesting glimpse into the creation of an industry, one that relied very much on craftsmanship to get it started.

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1938 Radio Has Awesome Dial

February 10, 2021 by Al Williams 19 Comments

[Mr. Carlson] is truly an old radio surgeon. The evidence? He recently restored an 83-year-old DeForest radio by transplanting an identical chassis from another similar radio. The restoration is fun to watch, but the 7D832 radio dial looks amazing. The dial is very colorful and the wooden knobs and preset selector are beautiful. To seal the deal, the center of the dial has a magic eye tube, giving the radio a retro high tech look.

The donor chassis needed some work before the surgery. In addition, [Carlson] makes some improvements along the way. The radio showed signs of previous service work, which is not surprising after 83 years.

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AM/FM Radio Gets Bluetooth Upgrade

February 2, 2021 by Tom Nardi 13 Comments

For many commercial broadcast radio has lost its luster, leaving an unknowable number of perfectly serviceable AM/FM radios to lie dormant. But they don’t have to. As [Dan Gebhardt] shows in his recent hack, integrating a Bluetooth audio receiver into portable radio may be easier than you think.

For this project, [Dan] wanted to make sure no original functionality was lost. The radio still functions on the AM/FM bands, but now with the flip of a switch, he can listen to the audio coming his way courtesy of a Apt-X low-latency Bluetooth receiver. It sounds like the link is quick enough that he can even use this as a wireless speaker for watching TV, which isn’t always possible with cheaper chipsets that introduce a noticeable lag.

The trick was to track down the receiver IC, a Silicon Labs chip similar to ones we’ve seen used in a few DIY radio projects previously. A peek at the datasheet told him which pins were carrying the audio signal, and after following them around the board, he found a convenient spot to cut the trace before it went into the volume control. From there is was just a matter of wiring in a SPDT slide switch that allowed him to select which device was passed through to the radio’s audio hardware.

While he had everything apart, [Dan] exorcised the Apt-X’s original 300 mAh LiPo pouch and replaced it with a DC-DC converter connected to the radio’s battery compartment. This allows him to run all of the hardware off of the same set of rechargeable NiMH cells, and also provides considerably improved runtime for the Bluetooth receiver.

Now as for physically integrating the Apt-X into the case of the radio…well, what can we say? [Dan] admits it’s a bit rough, but then the point was never to enter the thing into beauty pageants. It works well enough for his purposes, and in the end that’s all that matters.

Sirius XM Satellite Failure A Reminder That Space Is Risky (And That Satellite Insurance Is A Thing)

February 1, 2021 by Tom Nardi 58 Comments

It’s easy to imagine that once a spacecraft leaves Earth’s atmosphere and is in a stable orbit, the most dangerous phase of the mission is over. After all, that’s when we collectively close the live stream and turn our attentions back to terrestrial matters. Once the fire and fury of the launch is over with, all the excitement is done. From that point on, it’s just years of silently sailing through the vacuum of space. What’s the worst that could happen?

Unfortunately, satellite radio provider Sirius XM just received a harsh reminder that there’s still plenty that can go wrong after you’ve slipped Earth’s surly bonds. Despite a flawless launch in early December 2020 on a SpaceX Falcon 9 and a reportedly uneventful trip to its designated position in geostationary orbit approximately 35,786 km (22,236 mi) above the planet, their brand new SXM-7 broadcasting satellite appears to be in serious trouble.

Maxar Technologies, prime contractor for the SXM-7, says they’re currently trying to determine what’s gone wrong with the 7,000 kilogram satellite. In a statement, the Colorado-based aerospace company claimed they were focused on “safely completing the commissioning of the satellite and optimizing its performance.” But the language used by Sirius XM in their January 27th filing with the U.S. Securities and Exchange Commission was notably more pessimistic. No mention is made of bringing SXM-7 online, and instead, the company makes it clear that their existing fleet of satellites will be able to maintain service to their customers until a replacement can be launched.

So what happened, and more importantly, is there any hope for SXM-7? Neither company has released any concrete details, and given the amount of money on the line, there’s a good chance the public won’t get the full story for some time. But we can theorize a bit based on what we do know, and make some predictions about where things go from here.

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What Makes A Good Antenna?

January 24, 2021 by Jenny List 13 Comments

It sometimes seems as though antennas and RF design are portrayed as something of a Black Art, the exclusive preserve of an initiated group of RF mystics and beyond the reach of mere mortals. In fact though they have their difficult moments it’s possible to gain an understanding of the topic, and making that start is the subject of a video from [Andreas Spiess]. Entitled “How To Build A Good Antenna”, it uses the design and set-up of a simple quarter-wave groundplane antenna as a handle to introduce the viewer to the key topics.

What makes this video a good one is its focus on the practical rather than the theoretical. We get advice on connectors and antenna materials, and we’re introduced to the maths through online calculators rather than extensive formulae. Of course the full calculations are there to be learned by those with an interest, but for many constructors they can be somewhat daunting. We’re shown a NanoVNA as a useful tool in the antenna builder’s arsenal, one which gives a revolutionary window on performance compared to the trial-and-error of previous times. Even the ground plane gets the treatment, with its effect on impedance and gain explored and the emergence of its angle as a crucial factor in performance. We think this approach does an effective job of breaking the mystique surrounding antennas, and we hope it will encourage viewers to experiment further.

If your appetite has been whetted, how about taking a look at a Nano VNA in action?

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Manual Antenna Tuner Shows How Homebrewing Is Done

January 15, 2021 by Dan Maloney 10 Comments

If there’s anything about amateur radio that has more witchcraft in it than the design and implementation of antennas, we don’t know what it would be. On the face of it, hanging out a chunk of wire doesn’t seem like it should be complicated, but when you dive into the details, building effective antennas and matching them to the job at hand can be pretty complex.

That doesn’t mean antenna topics have to remain a total mystery, of course, especially once someone takes the time to explain things properly. [Charlie Morris (ZL2CTM)] recently did this with a simple antenna tuner, a device used to match impedances between a transmitter and an antenna. As he explains in the first video below, his tuner design is really just a Wheatstone bridge where the antenna forms half of one leg. A toroidal transformer with multiple taps and a variable capacitor forms an LC circuit that matches the high impedance antenna, in this case a multi-band end-fed halfwave, with the nominal 50-ohm load expected by the transceiver. A small meter and a diode detector indicate when the bridge is balanced, which means the transceiver is seeing the proper load.

The second video below shows the final implementation of the tuner; as a fan of QRP, or low-power operation, [Charlie] favors simple, lightweight homebrew gear that can be easily taken into the field, and this certainly fits the bill. A final video shows the tuner in use in the field, with a NanoVNA proving what it can do. As usual, [Charlie] protests that he not an expert and that he’s just documenting what he did, but he always does such a good job of presenting the calculations involved in component selection that any ham should be able to replicate his builds.

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