Retrotechtacular: Hallicrafters Goes To War

When the USA entered World War Two, they lacked a powerful mobile communications unit. To plug this gap they engaged Hallicrafters, prewar manufacturers of amateur radio transmitters and receivers, who adapted and ruggedized one of their existing products for the application.

The resulting transmitter was something of a success, with production running into many thousands of units. Hallicrafters were justifiably proud of it, so commissioned a short two-part film on its development which is the subject of this article.

The transmitter itself was a very high quality device for the era, but even with the film’s brief insight into operating back in the AM era the radio aspect is not what should capture your interest. Instead of the radio it is the in-depth tour of an electronics manufacturing plant in the war years that makes this film, from the development process of a military product from a civilian one through all the stages of production to the units finally being fitted to Chevrolet K-51 panel vans and shipped to the front. Chassis-based electronics requiring electric hoists to move from bench to bench are a world away from today’s surface-mount micro-circuitry.

So sit back and enjoy the film, both parts are below the break.

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Misleading Tech: Kickstarter, Bomb Sights, and Medical Rejuvinators

Every generation thinks it has unique problems and, I suppose, sometimes it is true. My great-grandfather didn’t have to pick a cell phone plan. However, a lot of things you think are modern problems go back much further than you might think. Consider Kickstarter. Sure, there have been plenty of successful products on Kickstarter. There have also been some misleading duds. I don’t mean the stupid ones like the guy who wants to make a cake or potato salad. I mean the ones that are almost certainly vaporware like the induced dream headgear or the Bluetooth tag with no batteries.

Overpromising and underdelivering is hardly a new problem. In the 30’s The McGregor Rejuvenator promised to reverse aging with magnetism, radio waves, infrared and ultraviolet light. Presumably, this didn’t work. Sometimes products do work, but they don’t live up to their marketing hype. The Segway comes to mind. Despite the hype that it would revolutionize transportation, the scooter is now a vehicle for tourists and mall cops.

One of my favorite examples of an overhyped product comes from World War II: The Norden Bomb Sight. What makes the Norden especially interesting is that even today it has a reputation for being highly accurate. However, if you look into it, the Norden–although a marvel for its day–didn’t always live up to its press.

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Rubber Tanks and Sonic Trucks: The Ghost Army of World War II

Winston Churchill once told Joseph Stalin “In wartime, truth is so precious that she should always be attended by a bodyguard of lies”. During World War II, the power of these bodyguards, in the form of military deception, became strikingly apparent. The German military was the most technologically advanced force ever encountered. The Germans were the first to use jet-powered aircraft on the battlefield. They created the enigma machine, which proved to be an extremely difficult system to break. How could the Allies possibly fool them? The answer was a mix of technology and some incredibly talented soldiers.

The men were the 23rd Headquarters Special Troops, better known as the Ghost Army. This unit was the first of its kind specifically created to deceive the enemy. Through multiple operations, they did exactly that. These 1100 soldiers created a diversion that drew German attention and gunfire to them, instead of the thousands of Allied troops they were impersonating.

The Ghost Army consisted of 4 distinct groups:

  • The 406th Engineer Combat Company Special were 166 “regular” soldiers – these men handled security, construction, and demolition.
  • 603rd Camouflage Engineers were the largest group at 379. As the name implies, the 603rd was created to engineer camouflage. 
  • 3132 Signal Service Company consisted of 145 men in charge of half-tracks loaded down with massive 500 watt speakers which could be heard for 15 miles. 
  • The Signal Company Special Formerly the 244th signal company, The 296 men of the Signal Company Special handled spoof radio communications.  The Germans heavily relied on captured and decoded radio messages to determine the Allies’ next move.

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Ask Hackaday: How Did They Shoot Down a Stealth Aircraft?

It was supposed to be a routine mission for U.S. Air Force Lt. Col. Darrell P. Zelko, a veteran pilot of the 1991 Gulf War. The weather over the capital city of Serbia was stormy on the night of March 27th, 1999, and only a few NATO planes were in the sky to enforce Operation Allied Force. Zelco was to drop 2 laser guided munitions and get back to his base in Italy.

There was no way for him to know that at exactly 8:15pm local time, a young Colonel of the Army of Yugoslavia had done what was thought to be impossible. His men had seen Zelco’s unseeable F117 Stealth Fighter.

Seconds later, a barrage of Soviet 60’s era S-125 surface-to-air missiles were screaming toward him at three times the speed of sound. One hit. Colonel Zelco was forced to eject while his advanced stealth aircraft fell to the ground in a ball of fire. It was the first and only time an F117 had been shot down. He would be rescued a few hours later.

How did they do it? How could a relatively unsophisticated army using outdated soviet technology take down one of the most advanced war planes in the world? A plane that was supposed be invisible to enemy radar? As you can imagine, there are several theories. We’re going deep with the “what-ifs” on this one so join us after the break as we break down and explore them in detail.

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Ditch that boring mouse for a military-grade trackball


The bad thing about this type of hack is that now [Tomek Dubrownik] needs to cut a hole in his desk to house the thing. He got this military grade trackball working over USB. It’s old, and could be used as a blunt weapon. But as the video shows it still makes a great input device.

He found the hardware on Allegro — a Polish auction site similar to eBay — for just $20. The original circuitry didn’t make a lot of sense, but a bit of probing with the old oscilloscope let him establish connections to the encoders which are read by some TI 54xx parts. Apparently they use the same logic as 7400 parts but are military grade. He chose a ATmega32u4 development board for his replacement control board. That chip has native USB support so the rest is just a matter of passing data like an HID input device. His code even lets him use those pushbuttons to toggle between cursor movement and window scrolling.

[Tomek] translated his post into English after some prompting by friends at the Warsaw Hackerspace. Here’s the original in Polish if you’re interested.

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Hacking the R-390A military shortwave radio receiver to transmit as well


After getting his hands on this relic [Gregory Charvat] manage to hack it, converting the receiver into a transceiver.

It may be old, but the R-390A is nothing to scoff at. It’s abilities include AM, code, and FSK operation from 500 kHz to 32 MHz. But it is a receiver with no way of transmitting on the same bands. This is where [Gregory’s] hack comes into play. He rerouted the variable-frequency oscillator feed inside of the R-390A in order to use his 20M single-sideband unit. Basically what this does is allow him to control everything from the 390, using the microphone from the SSB — along with some switching hardware — to transmit his own messages.

His demo video starts with him making a few contacts using the hacked equipment. He then spends some time at the whiteboard explaning the changes. This portion went over our heads, but it becomes more clear when he cracks open the case and shows the actual modifications.

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BigDog throwing cinder blocks


It’s as if giving cheetah-like speed to an advanced robot wasn’t good enough. The engineers over at Boston Dynamics must have been thinking to themselves, how can we make this thing even more menacing? The answer seems to be adding a highly dexterous articulated arm that gives the robot the ability to chuck objects as heavy as cinder blocks. We’re not kidding, look at the image above and you’ll see one mid-flight in the upper left. A quick search tells us that block probably weighs 30 pounds!

BigDog is a research project for the US military that we’ve seen navigating all kinds of terrain. It’s a heavy lifter able to carry loads where other machinery cannot. But now they’ve added an appendage that reminds us of an elephant’s trunk. It branches off of BigDog’s body where a quadruped’s neck would be. At the end of the appendage is a gripper that looks much like what you’d seen on industrial assembly robots. But enough talk, click through to see the action video. Oh, and if you didn’t pick up on the cheetah reference we made earlier you’ll want to check out this post.

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