Author Archives: clem.law@usa.net

1933 Two Tube Shortwave Regen

Eighty-five years ago this month, the February 1933 issue of Short Wave Craft carried the plans for this two-tube shortwave set dubbed the “Band Spread 2.”

The set, designed by George W. Shuart, W2AMN/W2CBC, featured a type 58 tube serving as regenerative detector, with a 47 pentode amplifying the audio sufficiently to drive a speaker. The case consisted of an aluminum can measuring 5x6x9, which were said to be readily available. To facilitate easy changing of the coils, the author suggested that the can be purchased with a hole punched in the top, with a cover to fit. All parts were mounted on a metal shelf, held in place from the bottom by 7/8 inch spacers.

One variable capacitor was mounted directly on the coil form for rough tuning, with the main tuning control serving as a bandspread. Coil winding data was shown for the 40 and 20 meter ham bands.

A “long low wire” was recommended for the antenna, although it was pointed out that many foreign stations were pulled in with just a ten foot antenna.

Happy Valentine’s Day!

Happy Valentine’s Day from OneTubeRadio.com!

The caption of this drawing from a 1943 Valentine’s Day themed ad reads: “Today! Right now! In February! Country-Style Frying Chickens!”

The magazine ad notes that in those days of meat shortages, Birds Eye frozen chicken was a wonderful way to bring novelty into your meals.

Simple 1918 Code Practice Circuit

A hundred years ago, the February 1918 issue of Popular Science showed this simple method for code practice without the need for a battery. A short length of wire was wrapped around the light circuit (the article noted that it wouldn’t work with a DC light circuit), through the key and headphones, and grounded. The result would be a convenient source of a 60-cycle tone.

Homemade Photovoltaic Cell

Seventy-five years ago this month, the February 1943 issue of Radio Craft showed how to make this rudimentary photovoltaic cell.

With some modification, it scould be easily duplicated today, and could be the basis for an interesting science fair project.

It consists of a strip of lead, as well as a copper plate covered with cuporus oxide. To achieve the coating, the copper plate is heated in a flame until it is covered by a black flaky substance, which is cupric oxide. Then, it is washed in a weak solution of ammonia, which reveals the light-sensitive cuprous oxide.

A sheet of lead should be available at a craft store, or can be ordered from Amazon. Similarly, a small piece of copper is readily available at a hardware store or Amazon.

The electrolyte is a somewhat more difficult proposition. The lead nitrate is somewhat hazardous, but should be safe if handled carefully. The main problem is that it is expensive. It is available on Amazon, both as a solution and as crystals, However, the prices might be outside the young mad scientist’s budget.

Fortunately, this site seems to suggest that ordinary salt water will function adequately as the electrolyte. Therefore, one suitable science fair project might be to determine what other electrolyte solutions might work best. All that would be required would be a voltmeter to see which configuration puts out the most electricity. The advanced student could skip buying the voltmeter and instead make this simple galvanometer.

Another fun project would be to demonstrate communication over a light beam, with a setup similar the one on this site. Your homemade photocell is hooked to the input of a small audio amplifier, and you hook an LED to the headphone jack of a radio or other audio source.

See Us at Ozarkcon!

This year, we will have a table at OzarkCon, at
which hams gather for two days of QRP (low power) related activities. Activities include a kit-building session, at which we will construct a 30 meter (10 MHz) transceiver, various seminars, a QRP flea market, music sessions, and more. Ozarkcon is sponsored by the Four State QRP Group (4SQRP). Even though this is my first Ozarkcon, it will be a bit of a homecoming, since I was present at the very first 4SQRP meeting in Seneca, MO, in 2002.

Ozarkcon is held the first weekend of April (this year, April 6-7, 2018) at The Stone Castle Hotel & Conference Centerin Branson, Missouri.

One of the trademark events at Ozarkcon is the Wacky Key Contest, an event designed to encourage non-traditional Morse code keys made out of things such as toasters. For inspiration, we offer this design from Joe Binko, who sent it in to Radio Craft magazine in February 1943.

We’re not sure if it’s wacky enough for first place, but we’re sure Binko’s design would have been in the running had OzarkCon been in existence in 1943. He converted a phone jack (presumably, a quarter-inch model) into a key by carefully cutting it apart, mounting it to a base, and extending one of the contacts. You should get the general idea from the diagram.

Among the big names attending is legendary sound engineer Bob Heil, K9EID, of Heil Sound, the only manufacturer to have an exhibit at the Rock n Roll Hall of Fame.

For more information about OzarkCon, visit their website or Facebook group.

Update (Feb. 18): When we checked today, all single rooms at the Stone Castle were fully booked. (After I posted this, someone else posted that some rooms were still available. So it’s probably worth a phone call. See the OzarkCon hotel page for information.) We will be staying at the nearby
Branson Surrey Inn. When we booked, rooms were only $42 per night, and it is located within walking distance of Ozarkcon.

1943 One-Tube Combination Code Oscillator/Regenerative Receiver

Seventy-five years ago this month, the February 1943 issue of Popular Science carried the plans for this one-tube combination receiver and code practice oscillator. The construction article, by Arthur C. Miller, noted that thousands of young men and women were learning code for civil defense purposes or prior to enlistment in the Signal Corps. A code oscillator was then impossible to buy.

A single switch changed the set from receiver to code oscillator. As a radio, the set ran on 45 volts, but the code oscillator required only 4.5 volts.

1938 Two-Tube Shortwave Regen

The February 1938 issue of Popular Science carried the plans for this two-tube regenerative shortwave receiver. While absent from the schematic diagram, the globe on the top was critical, since it allowed the shortwave fan to quickly spot the location of every new station logged, and easily spot the location where the message originated.

The circuit inside the box employed two type 30 tubes, one serving as regenerative detector, with the other serving as AF amplifier. Since regeneration operated more smoothly at a reduced voltage, the set employed two B batteries. A 22.5 volt battery powered the detector, with a 45 volt battery allowing for extra volume from the amplifier stage.

The cover of the set was hinged, to allow for changing the plug-in coils.

1958 Boys’ Life Shortwave Receiver: Part 2

We recently wrote about this three-transistor regenerative receiver from the January 1958 issue of Boys’ Life magazine.

I just received this picture of the completed receiver, constructed by Tom, WB3HLH, of Rockville, Maryland.

As a Cub Scout, he saw the receiver in the magazine and was very interested. This is understandable, since the magazine also carried a feature extoling the virtues of SWL’ing, as well as a listing of the prizes in the annual radio contest.

About 50 years later, he located the magazine and took it upon himself to make one. The article noted that the set was not for beginners, and his experience agrees with this assessment. He notes that the audio stage was simple, but it was very tricky to get the detector oscillating. As you can see, he very carefully duplicated the layout of the original project.

In addition to the coils described in the article (wound on plug-in coil forms), he wound a coil for the broadcast band. He reports that the set performs well on shortwave, both for broadcast and SSB signals. On the broadcast band, it pulls in all of the major East Coast stations, and signals as far west as KMOX in St. Louis.

The article calls for the use of four penlight batteries, but he reports using a 9 volt battery. The only other circuit modification is the addition of a 3.3 k resistor in parallel with a .01 uF capacitor on the emitter of the detector transistor.

Solar Fire Starter

When I worked for Radio Shack in an earlier lifetime, one of the more interesting products we sold was the solar cigarette lighter. It was something of a novelty item, but it was also fully functional. It was nothing more than a parabolic mirror, with a little holder at the focal point. It’s shown above in the 1980 Radio Shack catalog. The idea was to place a cigarette in the holder, point it at the sun, and after several seconds, the cigarette would start smoldering. No, it didn’t work at night or on cloudy days, but on a sunny day, it worked flawlessly.

The same simple device is now available at Amazon. Taking inflation into consideration, it’s not much more expensive than it was back in the day, and would serve as one method of starting a fire in an emergency. Yes, you’re better off if you have matches or a traditional lighter with you, but redundancy can be a good thing, and it’s kind of fun to amaze your friends by lighting a fire using solar power.

If you don’t smoke (this is one rare case where a cigarette could save your life), then you could use other similar tinder, such as tissue paper, dry grass, or leaves. This device won’t cause anything to burst into flame, so you’ll need more tinder at the ready. As soon as whatever you lit starts to smolder, you’ll need to transfer it to a larger pile of tinder, and then blow on it until it bursts into flame. You then keep adding larger fuel until you have a fire of the desired size. You don’t want the fire to go out after it gets dark, because obviously you won’t be able to light another one until morning.

(Some links on this page are affiliate links, meaning that we get a small advertising fee if you purchase from Amazon after clicking on the links.)

Sinking of the Tuscania, 1918

SS Tuscania. Wikipedia Image.

Today marks the 100th anniversary of the sinking of the SS Tuscania, February 5, 1918. The ship was a luxury liner of the Cunard Line, and was serving as a troop transport, carrying American troops to Europe. The ship left Hoboken with 384 crew and 2013 army personnel aboard. On the morning of February 5, a German submarine sighted the convoy and stalked it until darkness. At 6:40 p.m., it fired two torpedoes, one of which sent the ship to the bottom of the Irish Sea. 210 men were killed in the attack.

Color picture; An elderly man holding a glass and wearing a hat stands in front of a wooden lodge.

Harry Truman. Wikipedia image.

One of the notable survivors was 20-year-old soldier Harry R. Truman (not to be confused with the President), notable for becoming a victim of Mt. St. Helens in 1980.