1926 Homemade Battery Charger


1926octoberpmOne of the electronic components we take for granted today is the semiconductor diode for use as a rectifier. But even ninety years ago, if you wanted to build your own battery charger, you could do it at home, as shown by these plans from the October 1926 issue of Popular Mechanics.

To charge a six volt battery, this charger used a 12 volt doorbell transformer.  The rectifier consisted of a glass jar containing a solution of borax, with electrodes made of lead and aluminum.  The total cost of all of the parts was said to be $2.50.

Women in Radio: 1916

A hundred years ago this month, the October 1916 issue of Electrical Experimenter devoted a large portion of the magazine to “the Wireless Girl,” and featured on the cover this painting by George Wall.  Loyal readers will recognize the painting as being based on a photograph of Kathleen Parkin, 6SO/6BP, of San Rafael, California.  As we related in an earlier post, she built the quarter kilowatt transmitter shown here, along with a vacuum tube receiver, and had one of the more impressive stations on the West Coast.

In the Electrical Experimenter article, Miss Parkin writes of her interest in wireless:

With reference to my ideas about the wireless profession as a vocation or worthwhile hobby for women, I think wireless telegraphy is a most fascinating study, and one which could very easily be taken up by girls, as it is a great deal more interesting than the telephone and telegraph work, in which so many girls are now
employed. I am only fifteen, and I learned the code several years ago, by practising a few minutes each day on a buzzer. I studied a good deal and I found it quite easy to obtain my first grade commercial government license, last April.

It seems to me that every one should at least know the code, as cases might easily arise of a ship in distress, where the operators might be incapacitated, and a knowledge of the code might be the means of saving the ship and the lives of the passengers. But
the interest in wireless does not end in the knowledge of the code.

You can gradually learn to make all your own instruments, as I have done with my 1/4 kilowatt set.

There is always more ahead of you, as wireless telegraphy is still in its infancy.

Graynella Packer operating the wireless aboard the

Graynella Packer operating the wireless aboard the Mohawk.

Miss Parkin was not the only young woman at the forefront of radio, as the article cited a number of others. For example, Graynella Packer of Jacksonville, Florida, was the first woman wireless operator to serve on a commercial vessel, aboard the Mohawk of the Clyde Line, where she was in full charge of the vessel’s wireless.

Numerous other women radio operators were featured in the article, which stressed the role that wireless played in national preparedness.  The photo below shows a group of young women studying wireless at a summer preparedness camp.




“Vision of Peace,” 1936


Eighty years ago, the October 1936 issue of Popular Mechanics featured the familiar “Vision of Peace” sculpture in the Ramsey County Courthouse-St. Paul City Hall. The sculpture had been unveiled earlier that year.

The sculpture was created by Swedish sculptor Carl Miles, and is based on his own vision of Native American spirituality, with no connection to any particular Native American beliefs. It depicts five Native Americans seated around a fire holding their peace pipes. Emerging from the smoke is an unnamed god of peace speaking to all the world.

The statute originally honored the Minnesota soldiers who died in the First World War. Subsequently, names of those who died in other wars have been added. The name “Vision of Peace” was given in 1994, during a ceremony involving the three major Indian tribes of Minnesota.

The 60 ton 38 foot statue sits on a revolving base which turns 132 degrees every 2.5 hours.

1936 Radio Show


This cover spread from the October 1936 issue of Radio Craft showed some of the new sets getting ready to hit the market for 1937, as seen at the September 1936 New York Radio Show. Some of the sets featured here include:

  • RCA Model 10-T
  • General Household Utilities Co. Model 1541 Teledial Console
  • United Motors Service Model 3209, a 32 volt farm set
  • General Electric Model E-155
  • Crosley Model 167 Console
  • Noblitt-Sparks Industries Rhythm King Model 1127
  • Philco Model 116X DeLuxe
  • Zenith Model 7D-148
  • Admiral Model AM 387
  • Stromberg-Carlson Model 145-L
  • Detrola Model 102-C
  • Emerson Model L-143

1941: How Radio Will Defend America


On this date seventy five years ago today, October 18, 1941, less than two months before Pearl Harbor, Radio Guide magazine told all the ways that radio would defend America.  The author, an army officer who had previously served as an editor of the magazine, started by saying that the bombers would come first, make no mistake about it. They would do it, unless radio prevented them, as one of the nation’s first line defenses. He noted that the shores were ringed with listening stations on our territory, on distant islands and ships at sea, and aboard blimps above the ocean. One of those stations would see them coming, and radio would carry the message to commanders whose duty it was to defend our shores.

If enemies did get through, then “radio must do for America what it failed to do for France; it must tell Americans where to go and by what routes. When areas need to be evacuated, radio must instruct automobilists and truck-drivers to use certain roads and highways. The Army has first claim on the others. Indeed, it may be a part of one’s preparedness to keep his radio continuously tuned in. No other means can tell the public so quickly of threatened danger.”

Another aspect of national preparedness was monitoring foreign shortwave broadcasts. “Would you think, for example, that by listening to what Germans are telling Americans, both in North and South America, you could learn what Germany may do next? Well, you can. Even now German short-wave stations are talking to us at all hours. Each twenty-four hours they are sending us thirty thousand words of trickery and deceit. By following it for month after month we have learned that it assumes a pattern that is visible to experts. Our own Federal Communications Commission hires such experts and many others besides to listen to all foreign language broadcasts. Stations in Oregon, Texas, Maryland and Puerto Rico hear all broadcasts directed to this country and to South America. They make recordings of these broadcasts, turn them over to translators, then to analysts, then to psychologists. Result: The American government was warned ahead of time that Japan was going to occupy Indo-China. Germany’s attack on Russia was predicted within a few days.”

Air Corps radio operators.

Air Corps radio operators.  “A few months ago many of them were ‘hams’ you heard on short waves. Today they’re learning everything from signal codes to radio night-fighting technique.”

The article also noted how broadcasting had served the public by providing information and quieting rumors.  It concluded by noting that in peace, Americans had used radio better than any other nation.  “We have more stations, more receivers, more artists, more technicians, more listeners.  In war, if it comes, we shall also use radio best–there can be no doubt of that–and employ its multitude of services in order that a complete and glorious victory may quickly be ours.”

NPOTA: Lewis & Clark National Historic Trail


Preparing to send RF ‘cross the wide Missouri.

During the 2016  ARRL National Parks On The Air (NPOTA) event,  Amateur Radio operators are celebrating the 100th anniversary of the National Park Service (NPS) by setting up their equipment in NPS units  to make contact with other Amateurs around the world.  Since the beginning of the year, the event has been extremely popular, with over 13,000 activations from 450 different different units of the NPS and over 700,000 individual two-way contacts.  As I’ve reported in other posts, I’ve made contact with 281 different parks and operated multiple times from six parks in Minnesota and Wisconsin.

One of the event’s successes has been encouraging visits to the parks.  Until recently, my activations have been confined to the NPS units in Minnesota and Wisconsin.  Last week, I had to be in Sioux City, Iowa, for one of my continuing legal education programs.  The city lies along the path taken by Lewis and Clark as the traveled from St. Louis to the Pacific Ocean, and is therefore part of an NPS unit, the Lewis and Clark National Historic Trail.  Because the trail’s sheer length, and because it passes through so many other notable sites, it is the NPOTA’s most popular activation site, with over 13,000 individual contacts made.  Since my son had recently been studying Lewis and Clark in school, I decided to bring him along.

Sioux City marks the point where the only death during the 1804-06 Corps of Discovery’s expedition took place.  Sgt. Charles Floyd is buried under a prominent obelisk on a bluff overlooking the river.  The Sioux City riverfront contains two museums devoted to Lewis and Clark’s journey.  The first is in a drydocked former riverboat, the M/V Sergeant Floyd.  The ship was an Army Corps of Engineers Inspection Vessel.  Interestingly, the ship contains a ham station, although it’s supposed to be a recreation of the ship’s radio room.  As you can see from the photo below, the radio room is equipped with an E.F. Johnson Viking Valiant and a Hallicrafters S-40.  Even though these amateur rigs appear to be out of place, it was interesting to see this inadvertent ham station set up.


dsc01371The museum also contains the forensic reconstruction of Sgt. Floyd shown here, created from a plaster cast of his skull.

The second museum on the riverfront is the Sioux City Lewis & Clark Interpretive Center, which includes animatronic versions of Lewis, Clark, President Jefferson. and “Seaman,” the expedition’s Newfoundland dog.

Conditions were relatively poor the day I visited the site, and my initial attempt with a mobile antenna was unsuccessful.  Since the day was nice, I returned and set up a dipole at a picnic shelter overlooking the river and made ten contacts on 20 meter CW.

Read More at Amazon

Wartime Lamp Radio


Despite wartime parts shortages, the young man shown here was able to furnish his room with a radio, courtesy of plans found in the October 1944 issue of Popular Mechanics.

The lamp is not merely ornamental; it is part of the circuit. The 40-watt bulb serves to drop the line voltage to light the tube filaments. Two tubes are used, either type 37 or 76. The article noted that these tubes could be found in an old set, or in the radio student’s junk box. One served as a rectifier, with the other one serving as regenerative detector. The cabinet is a wooden file box. The lamp socket comes from the dime store and is mounted on a curtain rod secured to a wooden block on the cabinet with glue. The switch on the lamp socket turned on both the lamp and radio.

The coil was wound on a cardboard tube, and wire from an old transformer or filter choke could be used.

The set was billed as a “Desk Lamp DX’er for Boy’s Room.” For best selectivity on local stations, the article recommended an indoor antenna of 15 feet. For pulling in DX, it recommended a long and high outdoor antenna.

The article notes that no external ground is used, but doesn’t explain why not. Since the set is connected directly to the AC wiring, adding an external ground would run a 50/50 chance of blowing a house fuse (or in a modern home, popping a GFI). And anyone planning to make a modern recreation should be aware that the set isn’t exactly safe. One side of the headphones is connected directly to the AC line, and the antenna connection has only one capacitor between it and a hot wire. So the modern parent, before giving one of these interesting sets to Junior to put in his room, would probably be well advised to include an isolation transformer.


Click Here For Today’s Ripley’s Believe It Or Not Cartoon

National Parks On The Air: Appalachian Trail


During 2016, the American Radio Relay League (ARRL) is conducting its National Parks On The Air (NPOTA) event, in which  Amateur Radio operators set up their equipment in units of the National Park Service (NPS) to make contact with other Amateurs around the world.  Since the beginning of the year, the event has been extremely popular, with over 13,000 activations from 450 different different units of the NPS and over 700,000 individual two-way contacts.  As I’ve reported in other posts, I’ve made contact with 278 different parks, operated multiple times from six parks in Minnesota and Wisconsin, and plan to activate additional parks in the Midwest before the end of the year.

One of the surprises of this event has been the popularity of the National Scenic Trails.  I’ve operated from two, the North Country National Scenic Trail and the Ice Age National Scenic Trail.  These operations are a bit more challenging, since the event rules require all equipment to be hand carried to the operating location, rather than operating from a vehicle.  I would have expected this restriction to make the scenic trails less popular, but the reality has been quite different.  In fact, two scenic trails are in the top ten of parks activated.  The North Country Trail has seen 249 activations with 9932 individual contacts, and the Appalachian Trail has had 239 activations with a total of 6700 contacts.

The Appalachian Trail is probably the most famous of the nation’s National Scenic Trails.  It runs 2130 miles from Georgia to Maine.  I’ve made a number of contacts with stations on the trail.  Some of them were with small stations carried during long multiple day hikes.  Others were located closer to civilization,

(C) Copyright 2016 Tim Carter All Rights Reserved. Used by permission.

(C) Copyright 2016 Tim Carter All Rights Reserved. Used by permission.

Shown here is one of those in the latter category (as judged by the availability of pizza rather than dehydrated meals)  by Emily, KB3VVE, Keith, KB3FVN, and Tim, W3ATB, operating on a section of the trail in Pennsylvania.

Seventy-five years ago, 1941oct13life1this day’s issue of Life Magazine, October 13, 1941, carried a feature on the Appalachian Trail. The photo at the top of this post, a cabin along the trail at Shenandoah National Park, is from that article.   The photo at the right shows those same hikers approaching the cabin after an October snowstorm.  According to the article, the trail was completed in 1937.  As of 1941, only four persons had hiked the entire trail, but none of them had done so in a single uninterrupted session.  In contrast, thousands of hikers now hike the entire length of the trail each year.

1956 Boys’ Life SWL’ing


Notwithstanding the microphone and bug shown in the photo, the young ham shown here in the October 1956 issue of Boys’ Life is honing his SWL skills in preparation for the magazine’s forthcoming shortwave listening contest which would be announced the following month.

The accompanying article gives scouts pointers on the shortwave listening hobby, and reminds readers that there were a lot of interesting signals to be pulled in by even inexpensive receivers.  It pointed out that aspiring SWL’s should first take a look at the family’s radio in the living room, since there was a good chance that it pulled in the shortwave bands in addition to standard broadcasts.

The article appears to be a reprint of the same article that appeared in the October 1952 issue.  The author was Roger Legge, who penned the “English Broadcasts to North America” feature in Popular Electronics for many years.  The byline of the 1952 article also identified him as the Frequency Assignment Officer of the Voice of America.

Click Here For Today’s Ripley’s Believe It Or Not Cartoon

1941 Two-Tube Superhet


Seventy-five years ago this month, the October 1941 issue of Popular Science showed how to put together this two-tube superheterodyne broadcast set. With a 20 foot antenna lying in the floor, the set would provide loudspeaker volume.

The article noted that even a few years earlier, a superhet would consist of at least seven tubes. But with advances in tube technology, this two-tube set was now possible. A 1A7GT pentagrid tube served as first detector and local oscillator. This was fed to the triode section of a 1D8GT which served as detector. The other half of the 1D8GT served as audio amplifier to drive the speaker.

This was a battery set, with a 1.5 volt dry cell running the filaments. The B+ voltage came from a 90 volt battery, with a 7.5 volt C battery also used.

Since batteries were in relatively short supply during the war, it’s likely that any readers who built this set probably left it on the shelf for most of the next four years.


Click Here For Today’s Ripley’s Believe It Or Not Cartoon