Life Imitates ART (ART-13, That Is)

[Mr. Carlson] has been restoring vintage military radios, and as part of his quest, he received an ART-13 transmitter. Before he opened the shipping box, he turned on the camera, and we get to watch from the very start in the video below. These transmitters were originally made by Collins for the Navy with an Army Air Corps variant made by Stewart-Warner. Even the Russians made a copy, presumably by studying salvaged units from crashed B-29s.

The transmitter puts out 100 watts at frequencies up to 18.1 MHz. The tubes needed a plate supply, and so, like many radios of the era, this one used a dynamotor. Think of it as a motor running at one voltage and turning a generator that produces a (usually) higher voltage. If you ever used a radio with one, you know you didn’t need an “on the air” sign — the whine of the thing spinning would let everyone know you had the key or microphone button pushed down. It’s an interesting piece of bygone tech that we’ve looked into previously.

The transmitter wasn’t in perfect shape, but we’ve seen worse. When the lid comes off, you can practically smell the old radio odor. There are tubes, coils, and even a vacuum relay, presumably for transmit/receive switching of the antenna. [Carlson] also tears open the dynamotor which is something you don’t see every day.

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Inside A 1940’s Spy Radio

The RCA CR-88 was a radio receiver made to work in top-secret government eavesdropping stations. As you might expect, these radios are top-of-the-line, performance-wise, at least when they are working correctly. [Mr. Carlson] has one on his bench, and we get to watch the show on his recent video that you can see below.

Interestingly, [Mr. Carlson] uses some Sherlock Holmes-like deductive reasoning to guess some things about the radio’s secret history. The radio’s design is decidedly heavy-duty, with a giant power transformer and many tubes, IF transformers, and large filter capacitors.

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Retrotechtacular: Making Chains

We take the everyday materials of engineering for granted, as ubiquitous components rather than as complex items in their own right. Sure, we know that an integrated circuit represents the pinnacle of a hundred years’ development in the field of electronics, but to us it’s simply a black box with some wires. Even with more basic materials it’s easy to forget the work that goes into their manufacture, as for example with the two videos below the break. They both take a look from a very different angle at the creation of the same product: metal chain. However, the approaches couldn’t be more different as the two examples are separated by about a century and with vastly different techniques and material.

The first film follows the manufacture of the chain and anchor that would have been found on a ship around the turn of the twentieth century. One of the text frames mentions Netherton Works, allowing us to identify it as being filmed at N. Hingley & Sons, a specialist anchor and chain manufacturer based in the area to the west of the English city of Birmingham known as the Black Country. It’s a window on a manufacturing world that has entirely disappeared, as large gangs of men do almost every task in the process by hand, with very few automated steps. There is scant regard for health and safety in handling the huge pieces of red-hot metal, and the material in question is not the steel we’d be used to today but wrought iron. The skill required to perform some of the steps such as forge-welding large anchor parts under a steam hammer is very significant, and the film alone can not convey it. More recent videos of similar scenes in Chinese factories do a better job.

The other video is contemporary, a How It’s Made look at chain manufacture. Here the chains involved are much smaller, everything is done by automated machinery, and once we have got over marveling at the intricacy of the process we can see that there is far more emphasis on the metallurgy. The wire is hard drawn before the chain is formed, and then hardened and annealed in a continuous process by a pair of induction heaters and water baths. I’m trying really hard to avoid a minor rant about the propensity of mass-market entertainment such as this for glossing over parts of the process. A keen eye notices that each link has become welded but we are not shown the machine that performs the task.

Most of us will never have the chance of a peek into a chain factory, so the medium of YouTube industrial films and videos is compulsive viewing. These two views of what is essentially the same process could not be more different, however it would be wrong to assume that one has replaced the other. There would have been mechanised production of small chains when the first film was made, and large chains will still be made today with fewer workers and from arc-welded steel rather than wrought iron. Plants like the Hingley one in Netherton may have closed in the 1980s, but there is still a demand for chains and anchors.

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A Vintage Interface For A Modern Radio

The arrival of affordable software defined radio technologies over the last couple of decades has completely changed the way that radio amateurs and other radio enthusiasts approach the airwaves. There’s a minor problem with most software defined receivers though, being by their nature software driven they will usually rely on a host computer for their interface. Thus the experience is one of clicking mouse buttons or using keyboard shortcuts rather than the mechanical analogue dial interfaces that provided easy control of older radios.

Meccano encoder mounts for the win!
Meccano encoder mounts for the win!

This is a problem that has been addressed by [Jon Hudson, G4ABQ], with one of his SDRplay receivers. He’s mounted it and its control PC in the chassis of a very aged and non-functional Marconi CR100 communication receiver, and given it a control interface that only uses the Marconi’s front panel controls (YouTube link). A rotary encoder has been grafted onto the Marconi tuning capacitor with what looks like some Meccano, and in turn that feeds an Arduino which behaves as a keyboard for the benefit of the PC. Some extra buttons have been added for mode selection, spectrum zoom and shift, and care appears to have been taken to give their labels a period feel. Arduino code came courtesy of [Mike Ladd, KD2KOG]. The result is a very controllable SDR receiver, albeit one in a rather large case.

If you are interested in the project then we are told that it will be on the RS stand at Electronica in Munich next week, meanwhile we’ve put the video below the break.

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