Cold War Listening Post Antennas

March 20, 2023 by Al Williams 32 Comments

With a UHF antenna, it is easy to rotate a directional antenna to find the bearing to a transmitter. But at HF, it is more common to use an array of antennas that you can electrically switch as well as analyze the phase information between the elements. [Ringway Manchester] has a look at the “elephant cage” antenna used by the US Iron Horse listening network from the 1950s. You can see a video about the giant antenna system, the AN/FLR-9.

Technically, the ring of concentric antenna elements forms a Wullenweber antenna. The whole thing consists of three rings built on a ground screen nearly 1,500 feet across. The outer ring covers from 1.5 to 6 MHz or band A. The band B ring in the center covers 6 to 18 MHz. The inner ring covers band C which was from 18 to 30 MHz. Band A was made up of 48 monopoles while band B used 96 elements. The much smaller band C elements were 48 pairs of horizontally polarized dipoles. Continue reading “Cold War Listening Post Antennas” →

London Bridge Has Fallen — By Radio

September 10, 2022 by Jenny List 25 Comments

One of the global news stories this week has been the passing of the British monarch, Queen Elizabeth II. Since she had recently celebrated 70 years on the throne, the changing of a monarch is not something that the majority of those alive in 2022 will have seen. But it’s well known that there are a whole suite of “London Bridge has fallen” protocols in place for that eventuality which the various arms of the British government would have put in motion immediately upon news from Balmoral Castle. When it became obvious that the Queen’s health was declining, [Hackerfantastic] took to the airwaves to spot any radio signature of these plans. [Update 2022-09-11] See the comments below and a fresh Tweet to clarify, it appears these were not the signals they were at first suspected to be.

What he found in a waterfall view of the 4 MHz military band was an unusual transmission, a set of strong QPSK packets that started around 13:40pm on the 8th of September, and continued on for 12 hours before disappearing. The interesting thing about these transmissions is not that they were a special system for announcing the death of a monarch, but that they present a rare chance to see one of the country’s Cold War era military alert systems in action.

It’s likely that overseas embassies and naval ships would have been the intended recipients and the contents would have been official orders to enact those protocols, though we’d be curious to know whether 2022-era Internet and broadcast media had tipped them off beforehand that something was about to happen. It serves as a reminder: next time world news stories happen in your part of the world, look at the airwaves!

The Russian Woodpecker: Official Bird Of The Cold War Nests In Giant Antenna

May 11, 2021 by Kristina Panos 44 Comments

On July 4th, 1976, as Americans celebrated the country’s bicentennial with beer and bottle rockets, a strong signal began disrupting shortwave, maritime, aeronautical, and telecommunications signals all over the world. The signal was a rapid 10 Hz tapping that sounded like a woodpecker or a helicopter thup-thupping on the roof. It had a wide bandwidth of 40 kHz and sometimes exceeded 10 MW.

This was during the Cold War, and plenty of people rushed to the conclusion that it was some sort of Soviet mind control scheme or weather control experiment. But amateur radio operators traced the mysterious signal to an over-the-horizon radar antenna near Chernobyl, Ukraine (then part of the USSR) and they named it the Russian Woodpecker. Here’s a clip of the sound.

The frequency-hopping Woodpecker signal was so strong that it made communication impossible on certain channels and could even be heard across telephone lines when conditions were right. Several countries filed official complaints with the USSR through the UN, but there was no stopping the Russian Woodpecker. Russia wouldn’t even own up to the signal’s existence, which has since been traced to an immense antenna structure that is nearly half a mile long and at 490 feet, stands slightly taller than the Great Pyramid at Giza.

This imposing steel structure stands within the irradiated forest near Pripyat, an idyllic town founded in 1970 to house the Chernobyl nuclear plant workers. Pictured above is the transmitter, also known as Duga-1, Chernobyl-2, or Duga-3 depending on who you ask. Located 30 miles northeast of Chernobyl, on old Soviet maps the area is simply labeled Boy Scout Camp. Today, it’s all within the Chernobyl Exclusion Zone.

It was such a secret that the government denied it’s existence, yet was being heard all over the world. What was this mammoth installation used for?

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Boat Anchor Nixie Clock Plays The Cold Warrior Role Convincingly

April 27, 2021 by Dan Maloney 13 Comments

The early Cold War years may have been suffused with existential dread thanks to the never-ending threat of nuclear obliteration, but at least it did have a great look. Think cars with a ton of chrome, sheet steel toys with razor-sharp edges, and pretty much the entire look of the Fallout franchise. And now you can add in this boat anchor of an electromechanical Nixie clock, too.

If [Teti]’s project looks familiar, perhaps it’s because the build was meant as an homage to the test equipment of yore, particularly some of the sturdier offerings from Hewlett-Packard. But this isn’t some thrift store find that has been repurposed; rather, the entire thing, from the electronics to the enclosure, is scratch built. The clock circuit is based on 4000-series CMOS chips and the display uses six IN-1 Nixies. Instead of transistors to drive the tubes, [Teti] chose to use relays, which in the video below prove to be satisfyingly clicky and relaxing. Not relaxing in any way is the obnoxious alarm, which would be enough to rouse a mission control officer dozing in his bunker. [Teti] has a blog with more details on the build, the gem of which is information on how he had the front panel so beautifully made.

We can’t say enough about the fit and finish of this one, as well as the functionality. What’s even more impressive is that this was reportedly [Teti]’s first project like this. It really puts us in mind of some of the great 6502 retrocomputer builds we’ve been seeing lately.

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The False Alarm That Nearly Sparked Nuclear War

April 16, 2021 by Lewin Day 54 Comments

The date was September 26, 1983. A lieutenant colonel in the Soviet Air Defence Forces sat at his command station in Serpukhov-15 as sirens blared, indicating nuclear missiles had been launched from the United States. As you may have surmised by the fact you’re reading this in 2021, no missiles were fired by either side in the Cold War that day. Credit for this goes to Stanislav Petrov, who made the judgement call that the reports were a false alarm, preventing an all-out nuclear war between the two world powers. Today, we’ll look at what caused the false alarm, and why Petrov was able to correctly surmise that what he was seeing was an illusion.

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Civil Defense Disco Ball Rocks Ground Zero

January 15, 2021 by Tom Nardi 9 Comments

Old Civil Defense survey meters like the V-715 are interesting conversation starters, but of very little practical use today. These devices were intended to be a sort of litmus test that survivors of a nuclear blast could use to determine when it was safe to venture out of their radiation shelter: if the needle on the meter moves, even when it’s on the most sensitive setting, you should probably go back inside. Since [Hamilton Karl] would (hopefully) never need such an indicator, he decided to have a little fun with this Cold War holdover and turn it into a Disco Containment Unit.

Technical details are a little sparse on this one, but we can infer most of it just from the pictures. In place of the original meter [Hamilton] has mounted a tiny mirrored ball inside of a protective cage, which is spun by a geared motor that’s occupying the space that used to be taken up by the ion chamber.

A handful of Adafruit NeoPixel RGB LEDs, an Arduino Nano, and a few switches to control it all round out the functional aspects of the build, and a new disco-themed trefoil replaces the original Civil Defense logo on the side. The project page mentions there’s a piezo buzzer onboard that performs a stirring rendition of “Stayin’ Alive” by the Bee Gees, but alas there’s no video that shows it in action.

Thanks to the rugged construction and built-in handle of these old survey meters, [Hamilton] can now take the party with him wherever he goes. Not that he can really go anywhere with this whole global pandemic hanging over our heads, but at least he’ll be ready when things start trending towards normal. In a way the device’s functionality has now been reversed from how it originally worked, since the meter going wild will now be an indicator that its safe to come out.

While the V-715 isn’t of much use outside of a post-apocalyptic hellscape, the V-700 is actually a proper Geiger counter that’s still useful for surveying or research. An important distinction to remember if you ever get a chance to snap one of them up at a swap meet or flea market. Whenever we can start having those again, anyway.

Indoor Antennas Worthy Of 007

December 26, 2020 by Al Williams 21 Comments

Many ham radio operators now live where installing an outdoor antenna is all but impossible. It seems that homeowner’s associations are on the lookout for the non-conformity of the dreaded ham radio antenna. [Peter] can sympathize, and has a solution based on lessons of spycraft from the cold war.

[Peter] points out that spies like the [Krogers] needed to report British Navy secrets like the plans for a nuclear boomer sub to Russia but didn’t want to attract the attention of their neighbors. In this case, the transmitter itself was so well-hidden that it took MI5 nine days to find the first of them. Clearly, then, there wasn’t a giant antenna on the roof. If there had been, the authorities could simply follow the feedline to find the radio. A concealed spy antenna might be just the ticket for a deed-restricted ham radio station.

The antenna the [Kroger’s] used was a 22-meter wire in the attic of their home. Keep in mind, the old tube transmitters were less finicky about SWR and by adjusting the loading circuits, you could transmit into almost anything. Paradoxically, older houses work better with indoor antennas because they lack things like solar cell panels, radiant barriers, and metallic insulation.

Like many people, [Peter] likes loop antennas for indoor use. He also shows other types of indoor antennas. They probably won’t do as much good as a proper outdoor antenna, but you can make quite a few contacts with some skill, some luck, and good propagation. [Peter] has some period spy radios, which are always interesting to see. By today’s standards, they aren’t especially small, but for their day they are positively tiny. Video after the break.

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