Monthly Archives: June 2016

Making Your Own Nomograms: 1946


For many years, a standard feature of most radio and electronics magazines was the nomogram (or nomograph).  Before the days of the electronic calculator, it was a convenient way to do calculations of a given formula. The nomogram consisted of three or more scales with the values of a given equation. If you knew two values, you would place a straightedge between them, and the point where the straightedge intersected the third scale, that would be the answer.

The example at the top of the page is a nomogram of Ohm’s Law, from the April 1967 issue of Electronics World. It shows Ohm’s Law, and it also has superimposed another two scales for calculating the power rating of the resistor. Such graphs were very common. In fact, people cut them out of the magazines for future reference. At one hamfest, I once took home a thick binder labeled “charts and nomos,” in which the previous owner had amassed a large collection of such items.

A nomogram is essentially the same as a slide rule, preset for a particular equation. For recurring problems, even quite complex ones, it was a great time saver.

Seventy years ago, Radio Craft Magazine, in its June and July 1946 issues, ran a series on how to make your own nomogram. To illustrate the concept, it started with the simplest possible case, and addition nomograph:


As you can see, this version has three vertical scales, equally spaced. The outer scales have their values placed twice as far apart as the inner scale. To add numbers on the outside scales, you place the straightedge on them, and the point where it intersects the center line is the sum. The concept gets more useful when the linear scales are replaced with logarithmic scales. Now, the nomogram can be used for multiplication, as with a slide rule. The straightedge is placed over the values in the outer scales, and the intersection with the center scale represents the product. Similarly, division can be done by placing the straightedge over one outer scale and the center, and the other scale shows the quotient:


The article showed how to handle exponents by moving the center scale. For example, this graph calculates power from the formula P = I^2 R:


By moving the center scale closer to the current scale, more weight is given to the current. In this case, the current is raised to the power of 2.

The following month’s issue went on to show how to handle more complicated situations, such as reciprocals and square roots. We take for granted these days how easy it is to do calculations with a calculator. But in cases where the same equation had to be repeated over and over, the nomogram represented an easy way to do it with nothing but a straightedge. And making your own nomogram required little more than a few sheets of logarithmic graph paper.

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1916: Uncle Sam Needs Radio Men

1916June19One hundred years ago today, the United States was close to declaring war, but it wasn’t the European war.  On March 9, 1916, Pancho Villa had raided Columbus, New Mexico.  Sixty to eighty of Villa’s men were killed, along with a dozen Americans.  President Wilson ordered 5000 American soldiers into Mexico as a punitive expedition to capture Villa.  By June, the state militias had been called up and sent to the border.

Among the skills desperately needed were telegraph operators, both landline and wireless. This item appeared in the Washington Times, June 19, 1916.

According to the article, the D.C. National Guard had a need for “men who can speak two languages that are not United States: the Morse code and the persuasive expletives that awaken the potential dynamic forces of the festive army mule.”

In other words, in addition to mule skinners, the Guard needed trained telegraphers. “The telegraph is playing an increasingly important part in the conduct of war, and the men in the telegraph corps of the signal company of the District national guard are given the best sort of inducements to join the organization.” The article noted that pay ran as high as $76 per month, “considerably more than men employed in similar work in civilian employments receive.”

In addition to landline telegraphers, the army needed radio men. “There are more than 250 amateur radio operators in Washington who are members of the national organization of wireless telegraph operators. Inducement have been offered a number of these men to join the national guard, and several inquiries were made today regarding the chances for radio work. It is understood that wireless equipment is much in use on the Mexican border.”

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1941 “Fool-Proof” Transmitter by Don Mix, W1TS


Seventy-five years ago this month, QST carried plans for a two-tube “fool-proof rig for 80 and 40 meters.” The author, Don Mix, W1TS, noted that there were two competing factors in coming up with a design: On the one hand, the cost had to be kept low and the circuit be capable of easy construction. But on the other hand, ease of adjustment and operation was important for the beginner. Mix noted that many designs, usually one tube, had erred on the side of low cost, and could prove frustrating for the beginner to operate.

For that reason, Mix settled on this two-tube design using two 6V6’s, or two 6L6’s with a lower plate voltage. One was used as the oscillator with the second serving as final amplifier. This arrangement would keep the keying chirp-free, since the oscillator didn’t need to work at full power. And the final amplifier could be designed in such a way as to prevent parasitic oscillation without the need for the beginner to go through the process of neutralizing the final stage.

The resulting circuit is shown below. The author noted that construction on a metal chassis would be ideal, and took no more time or skill. However, metalwork might require tools not found in the average household, so he showed how to build the set with a wooden chasis, by mounting two 1×2 strips on top. They were spaced such that the sockets for the tubes, coils, and crystal could be mounted between them. The variable condensers could be mounted on the front panel.


He also included a diagram for a suitable power supply which could be built on a similar chassis.

The author was on the ARRL staff, and wrote a number of articles for QST. In 1968, he produced a somewhat updated version of a transmitter for the novice, and that design was later reprinted in “How To Become A Radio Amateur.”

Mix had been on the MacMillian polar expedition in 1923, operating station WNP aboard the Bowdoin. Commander McMillian had recognized the value of radio, but didn’t think that sufficient funds were available. At some point, he had spoken to Hiram Percy Maxim, who suggested that many amateurs would be eager to take part. Mix secured the slot, and operated a station provided by Zenith. On a weekly basis, he transmitted a 500 word press dispatch, handled other traffic, and transmitted a list of amateur calls heard from the Arctic.

As we recounted earlier, one staton who was able to maintain contact with the Bowdoin is a young Art Collins, 9CXX, of Cedar Rapids, Iowa.

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1926 Telegraph Practice Set


Here’s another more or less self-explanatory homemade telegraph set, from the pages of Popular Mechanics 90 years ago this month, June 1926. Unlike the one we featured a few weeks ago from 1916, this one relies on manufactured doorbell buzzers, and is intended to allow practice for aspiring radio operators, since the buzz of the doorbell more closely simulates the sound of a radio telegraph signal, as opposed to the clacking of the sounder of the landline telegraph shown in the earlier example. The article noted that the sound of the buzzer might be a lower pitch than desired, but explained how to increase the pitch by strategically placing a piece of paper in the buzzer.

This one can be set up either for practice at a single station, or two units can be interconnected as shown here. To receive, the other station needs to short out the key with the shorting bar shown.

The set is powered by two dry cell batteries. The article notes that if the two stations are some distance apart, such as in different houses, then a set of batteries might be necessary at each station.

In case you’re wondering, you can still find old-fashioned door bells, although they are getting harder to find.

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1941 Home Entertainment Center


The unnamed California radio enthusiast shown below is making adjustments to the audio amplifier section of his home entertainment system, shown here in the June 1941 issue of Popular Mechanics.

1941JunePM2To avoid cluttering his home with numerous cabinets, he combined all of his entertainment devices into one, resulting in what he called a “phono-cine-radio-recordo-graph.” It combined an all-band radio, phonograph, home recorder, and sound movie projector into a single unit.

The high-fidelity amplifier supplied the sound for all of the devices and drove three speakers with a crossover network. 16mm movies were projected onto a mirror in front and then onto a beaded movie screen. The set also incorporated a clock which could turn the radio on and off automatically. The system was also equipped with a remote control, and had remote speakers in other rooms.

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Fredda Josephine Brown, WDAF Kansas City, 1926


Shown here on this day’s issue of Radio Digest ninety years ago, June 15, 1926, is Miss Fredda Josephine Brown, who was heard over the airwaves of who was heard over the airwaves of WDAF, Kansas City, Missouri.  The magazine noted that her beauty was equalled only by her versatility, since she was accomplished as a violinist and pianist, and also gave readings over the station. She was apparently still in high school at the time, since she  graduated in 1927 from Westport High School in Kansas City, which closed in 2010.

The station, “The Kansas City Star” signed on originally as experimental station 9XAB in 1922 at 833 kHz, and assumed the WDAF call letters later that year. It moved around the dial in the 1920’s, making appearances at 750, 730, 680, 820, and 810 kHz. According to the magazine, its wavelength in 1926 was 365.6 meters, or 820 kHz. In 1928, it moved to 610 kHz, where it was an affiliate of NBC.

In 2003, the station changed to a sports format and changed its call letters to KCSP. The original call letters are still used on FM and TV.

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Flag Day 1916

The flag of the United States was adopted by the Second Continental Congress on June 14, 1777, and Flag Day had been celebrated in many places on June 14. But it was a hundred years ago today when it began as a national observance in a big way. In preparation for leading the United States into the European war, President Wilson officially proclaimed June 14, 1916 as Flag Day. The event was marked by a massive parade led by the President, shown here. Billed as a “Preparedness Parade,” Wilson, wearing a straw hat, led the parade down Pennsylvania Avenue to the White House, where he sat in review. According to the Washington Times, “with shoulders thrown back and head erect, President Wilson, carrying a large silken flag, marched on foot today at the head of Washington’s Preparedness Parade.”

At the White House, a reviewing stand, decked in patriotic colors, had been set up, and the President and his party reviewed the parade as the 60,000 participants passed.

The two in the picture in top hats were the President’s Secret Service detail.

Not surprisingly, Amateur Radio Operators were among those taking part in the Preparedness Parade.  As shown here in the order of the parade from the previous day’s Washington Herald, they marched just ahead of the Banks and Trust Companies.


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14th Amendment 150th Anniversary


Today marks the sesquicentennial of the passage by Congress of the 14th Amendment to the U.S. Constitution on June 13, 1866, which was ratified on July 9, 1868.  Section 1 provides:

All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside. No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any State deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.


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Nellie Melba, 1916

June121916This ad for Victrola appeared a century ago today, June 12, 1916, in the El Paso Herald.

Nellie Melba. Wikipedia image.

Nellie Melba recorded for Victor, and this ad reminds the readers that “‘Sweet as the voice of Nellie Melba’ is a musical proverb. The capture of her matchlessly pure tones in a fresh flow of beauty is an event of genuine importance to those who cherish genius.”

The particular record being advertised here was “Songs My Mother Taught Me” by Dvorak, available only on Victor Records. The twelve inch disc sold for $3. For those who did not yet own a Victrola, they could go to their nearest dealer, who would play the new Melba record or any other Victor music on machines from $10 to $400.

You can listen to the recording being advertised, which was recorded on January 12, 1916, at this video:

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1941 Phono Oscillator


In 1941, portable radios were becoming popular, and the June issue of Popular Science noted that “this summer there will be thousands of battery-operated portable radios in use on beaches, in parks, and on picnics and excursions everywhere. They will range from the camera-style midget or “personal” radios to the “twenty-pounders,” capable bringing in Europe on the short-wave band.”

To increase the versatility of any such set, the magazine showed how to make the battery-operated wireless phonograph shown here. “Phono oscillators” as they were sometimes called were fairly popular devices. They generally used only one tube to transmit the record audio to a nearby radio receiver. This was a cost-saving measure, since almost everybody owned at least one radio, and this scheme kept the parts count down. There was no need for a speaker or audio transformer. The record player described in this article simply followed the same concept in a portable. It used a single 1A7GT tube powered by a flashlight battery for filament voltage, and a 67.5 volt B battery. The other components included a standard plug-in coil for a receiver and a small variable condenser for tuning to an empty spot on the dial.1941JunePSschematic

The phonograph motor and turntable was of the wind-up variety, which the article stated could be had secondhand for about $2.50. The entire player fir in a suitcase available for less than $1. Everything was mounted on a Masonite panel cut to fit snugly on top of the suitcase. An antenna wired of 7 feet was used, which was placed near the back of the radio. The article noted that this was legal because “the power of this transmitter is so small that it will not radiate signals beyond a few feet. It is the only type of transmitter that can be operated without a license under Federal Communications Commission regulations.”

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