Category Archives: Articles

Radio: “One of history’s most important inventions”

(Source: CNN)

There are few more important inventions in the history of the world than the radio.

While in recent years it may have become less popular than television or the internet, it could be argued that the radio was the first electronic gadget to play a prominent part in people’s lives.

Radio is where the world first heard Britain declare war on Germany, where Orson Welles accidentally fooled the public into believing a real alien invasion was under way in his “War Of The Worlds” serial and where young people first heard Billy Haley’s “Rock Around The Clock,” spreading popular music around the world.

But it is not just an aural medium. Like all important pieces of technology, design has had an essential part to play in its evolution.[…]

Continue reading the full article on CNN’s website…

Seventy years ago, Thor Heyerdahl packed a National NC-173 and made history

The National NC-173

Many thanks to SWLing Post contributor, Kris Partridge (G8AUU), who sent the following feedback a few days ago. Sorry for missing the boat, Kris!

Kris writes:

Just under two weeks ago I was watching a Norwegian film on Polish TV (no, don’t ask) and knowing how the sight of old radio’s in films is of interest to you and your readers I was going to write but travel and work, Passendale100 commemorations in Belgium, got in the way. The radio in question was a National NC-173 receiver. And the film Kon-Tiki.

There is much written about the exploits of the voyage and the operators of LI2B. I give as an example from PA7MDJ http://pa7mdj.blogspot.co.uk/2016/10/the-kon-tiki-expedition-and-heroes-of.html?m=1 I leave it to PA7MDJ’s most excellent blog to tell more, he has some Nation Radio Company images from 1947 illustrating his piece and at the end there is a very extensive links listing.

But another reason for writing is that tomorrow, Monday, 07 August is the 70th anniversary of the end of the voyage as the raft landed on the reef. On the 67th anniversary the ARRL did an article on LI2B, why the 67th?

What happened on the 7th of August 1947, and in the 36 hours after, says much about the build quality of the National NC-173.

How many radios today would survive a dunking in seawater and after drying out still be working?

I’ve just been to my book shelves and after a small search found my copy of The Kon-Tiki Expedition published in 1950 given to me not too many years later.

You find LI2B in the book’s index twice. Once describing the operation of the radio ‘corner’ and a very QRP contact between the raft and Oslo Norway. 6 watts CW on 13990 kc. per second, the book being written in 1949 no kHz.

LI2B had been given permission to operate out of but adjacent to as well as in the 20 metre band. The second entry concerns what happen after the raft ends up on the reef and the radio shack and equipment got flooded.

They had been in contact before hitting the reef and there was a 36 hour window before the air search and rescue operations would begin. The drying out of the equipment took no little time and the writer describes how slowly the receiver came to life but no transmitter.

Finally they were able make contact, just before the 36 hrs ended,using a WW2 hand cranked resistance, the book says sabotage, transmitter.

Both the radio operators on the Kon-Tiki had been radio operators in the Norwegian resistance in WW2, only 2 years earlier.

If one puts LI2B into Google images quite an interesting assortment of radio related images are found (click here to view search), including QSL cards but the one I like best is this http://f6blk.net/photos/LI2Bshack_x1.jpg:

I’m sure I’ve seen an English language version, this one looks slightly cropped since the end of the ‘Earth’ wire is out of vision

Regards es 73 de

Kris G8AUU

How fascinating! Thanks so much for sharing this, Kris.

Again, apologies I didn’t get this posted prior to the 70th anniversary–I’m a tad behind (understatement alert) on email at the moment.

I have a particular affinity for The Kon-Tiki Expedition. I found a 1950s copy of the book while doing my undergraduate degree ages ago.

My 1950s copy of The Kon-Tiki Expedition in an archival cover.

The book played no small part in my fascination with anthropology–especially Heyerdahl’s version of “applied” anthropology. I went on to do my post grad work in anthropology at the London School of Economics. Indeed, I re-read that book before my finals to remind myself the significance of anthropology.

If you haven’t read The Kon-Tiki Expedition, I highly recommend you do so! Indeed, it’s about time I read it again.

I’m very curious how many SWLing Post readers have a National NC-173 sitting in their shack? Thor would tell you to take care of it, because it certainly took care of his crew!

Guam to California: CTF 75 successfully tests HF communications system

Electronics Technician 2nd Class Anthony Juarez and Electronics Technician 3rd Class Codie Flanagan, assigned to Naval Mobile Construction Battalion (NMCB)1, adjust frequency codes on a GRC-234 high-frequency base station at Naval Base Guam July 27, 2017. (Source: DVIDS)

(Source: Defense Video Imagery Distribution System)

NAVAL BASE GUAM , GUAM
08.04.2017
Story by Petty Officer 1st Class Torrey Lee
Commander, Task Force 75
Subscribe 5

Commander, Task Force (CTF) 75 successfully completed communications systems tests using high-frequency (HF) radio waves to broadcast voice and data 6,050 miles from Naval Base Guam to Port Hueneme, California, July 27, 2017.

The assessment tested the capabilities of expeditionary forces to use HF waves to deliver data over the Pacific. HF has become a viable alternative for military forces when more common forms of communication, such as satellites, are unavailable.

“In this particular back-up plan, we tested our ability to talk, and we were able to send text to one of our units that is across the Pacific Ocean,” said Lt. Cmdr. Timothy Carmon, a communications planner temporarily assigned to CTF-75. “The transmissions and receptions are not as fast as IP services, however we were still able to communicate in a timely manner with the distant end.”

Utilizing the assets of CTF-75’s Naval Mobile Construction Battalion (NMCB) 1, the command configured its antennae to broadcast to California. Once a successful voice transmission was received, communication directors at Navy Expeditionary Combat Command Pacific requested that CTF-75 try to send a data file.

“These data files allow us to save time,” said Electronics Technician 2nd Class Anthony Juarez, a communications supervisor assigned to NMCB 1. “We can send general diagrams, fire plans and points of interest. Instead of trying to verbally describe something, they [the recipient] have a graphic or a picture that gives them a better idea of the situation.”

Common communication devices used by the U.S. military incorporate satellites. CTF-75 has been testing HF systems in the case of satellite communication failure. HF is a frequency wave broadcast that is transmitted around the curvature of the Earth. Unlike other forms of frequencies, such as very-high frequencies and ultra-high frequencies, the transmission is not distorted by terrain or physical obstructions.

“We may not always have access to operational equipment or the latest assets, but as communicators we should have a backup plan that is ready to be executed,” said Carmon.

Guam is located in the western region of the Pacific. Having an HF range of 6,000 miles is equivalent to broadcasting from Japan to the U.S., or oppositely, from Japan to the middle of Africa. During this most recent test, CTF-75 was also able to establish communications with Mobile Diving and Salvage Unit 1 in Hawaii.

“We can hop our communications from island to island,” said Juarez. “This test gave us the opportunity to know we can push our system to the absolute max from Guam. There are definitely different systems out there, but our system is really efficient at long-range HF. As new radios are incorporated in the Navy expeditionary community, I have no doubt it will get faster, more reliable and easier to set up.”

CTF-75 is currently testing its communication abilities with subordinate commands which include Seabee units, riverine squadrons, cargo handlers, explosive ordnance disposal technicians, and expeditionary intelligence forces.

“This achievement was an important step in an effort to increase our capabilities to be prepared to execute missions in austere locations around the globe,” said Carmon. “Our expeditionary commanders may never need to communicate over a few thousand kilometers, but if the need arises our communicators will be able to provide the connection for that commander.”

CTF-75 is the primary expeditionary task force responsible for the planning and execution of coastal riverine operations, explosive ordnance disposal, diving engineering and underwater construction in the U.S. 7th fleet area of operations.

Read the full article at the DVIDS hub…

Lowell Thomas: “The Forgotten Man Who Transformed Journalism”

Many thanks to SWLing Post contributor, Bill Patalon, who shares the following story from The Smithsonian:

The Forgotten Man Who Transformed Journalism in America

Lowell Thomas was the first host of a TV broadcast news program, and adopted a number of other new technologies to make his mark in the 20th century

By the time Lowell Thomas turned 25, he’d already worked as a journalist, earned multiple degrees, and found a place on the faculty at Princeton University. But seizing a rare opportunity during World War I changed him from youthful overachiever to media heavyweight. During that conflict he met T.E. Lawrence, soon-to-be famous as “Lawrence of Arabia”—and Thomas played a large part in giving Lawrence that fame. The encounter launched Thomas into the media stratosphere with a groundbreaking multimedia presentation that captivated millions.

But while Lawrence’s work ended abruptly with his untimely death, Thomas went on to live a long, remarkable life. He traveled Europe, the Middle East, India, Afghanistan, New Guinea and Tibet, even meeting the Dalai Lama. He made fans out of Queen Elizabeth and Winston Churchill and led a prolific career in the news, making reports by print, radio, and TV—and reshaping them all into more formal, serious mediums.

Yet for a man with such a hyperbolic life, his legacy has been largely forgotten. Mitchell Stephens, a professor of journalism at New York University, set out to remedy that lapse in public memory with his new biography, The Voice of America: Lowell Thomas and the Invention of 20th-Century Journalism. Smithsonian.com talked with Stephens about his book, and why Thomas still matters today. […]

Click here to continue reading the full article at The Smithsonian online.

Many thanks for sharing this, Bill! What a fascinating fellow.

How to build a Milk Crate AM Broadcast Loop Antenna

Many thanks to SWLing Post contributor, James Townley, who shares the following guest post originally posted on his Shortwave/Medium Wave blog:


540 kHz to 1700 kHz Loop Antenna (Click to enlarge)

AM Broadcast Loop Antenna

by James Townley

Several years ago, I became interested in medium wave DXing. One of my limitations was the size of my yard, so I developed an interest in tuned loop antennas to compensate, because setting up a beverage antenna was out of the question. I experimented with different sizes of loops, and found that the bigger the aperture, the more gain the loop would have. The tuned loop antenna is also very directional, which allows you to reject, or null out interference from either noise or other stations. Loops are considered bi-directional in that they receive to the front and back, but not to the sides. The tuned loop antenna quickly became my weapon of choice for medium wave DXing.

Recently when the weather began allowing me to enjoy the outdoors, I decided to make another smaller loop antenna from a plastic milk crate I had lying around. I saw the idea on the internet when I observed that someone had used a milk crate for their loop. Click here to see a variety of tuned loop antennas that others have made. Whichever material you decide to make your loop antenna from, just make sure that it is not a conductive material. Wood, plastic, and cardboard seem to be popular materials for loop making. In the photo above, I am using my Sony ICF-2010 to listen to WCCO on 830 kHz. This station is nearly 200 miles south of me, but I am able to receive it with 9 LEDs lit on my signal strength meter while using the loop. There is no direct connection of the loop to the radio, it is inductively coupling with the radio’s own ferrite rod antenna.

If you are interested in making a loop antenna like mine, here are the materials you will need:
120 ft of 18ga insulated wire (I bought a 100 ft spool of cheap speaker wire and pulled the 2 conductors apart):

1 – Plastic milk crate
1 – 15 to 365 pF air variable capacitor (found in many old radios, or a google search to buy one from an internet store)
1 – Tuning knob. Any knob will do as long as it fits the shaft on the variable capacitor.
1 – Tape or wire ties. I used tape to secure the wire while winding, then hot glue when finished.

When you begin to wind your coil, use tape or a wire tie to secure the wire, and leave about a foot of wire. This extra foot of wire will later be soldered to the frame on the capacitor. As you wind your coil, pull the wire snugly and with each turn leave about a quarter inch spacing between each turn. The spacing isn’t critical as long as the spacing is consistent.  I wound 21 turns on my crate. This may differ for you, depending on the size of your crate, or the value of you capacitor. If you find that the bottom frequency isn’t low enough, you can add more wire to make a few more turns. This will lower the bottom frequency for you.

After winding the coil, you can solder each end of the coil to your capacitor. The beginning of the loop gets soldered to the frame of the capacitor, and the other end of the coil to the rotor solder lug on the side of the capacitor. If you do not have a soldering iron, you can use alligator clips to connect your loop coil to the capacitor as well. I secured my capacitor to the inside corner of the crate with hot glue. I put a generous amount of the hot glue onto the bottom of the capacitor frame, and held it to the crate until the glue cooled enough for the capacitor to stay on it’s own. I used enough to get the job done, but not so much that it interfered with the plates in my capacitor. The hot glue seemed to adhere very well. I then checked the spacing of my coil turns, and secured them with the hot glue as well.

I was very impressed with the results after spending some time with the loop. It’s small enough to maneuver around easily, but big enough to give it some gain, so I can listen to daytime DX. I may make another tuned loop using two crates to see how much more gain I get with the larger aperture.

Happy DXing,
James Townley


Many thanks, James, for sharing your project with us! This loop appears to be relatively simple and accessible even to those with little knowledge of soldering or homebrewing. I’m now wondering how a loop made of four milk crates might perform!

Click here to view James’ Shortwave/Medium Wave blog.