Monthly Archives: November 2021

1961 Student-Built Radio Telescope

1961NovEISixty years ago this month, the November 1961 issue of Electronics Illustrated featured this radio telescope constructed by high school student H. Mark Wahl of Cheyenne, Wyoming. The rack containing the electronics was a school locker. The door of the locker was removed to form the door, and the equipment was mounted facing what used to be the back.

The equipment consisted of a standard FM broadcast receiver which had been converted to AM by eliminating the limiter and discriminator. A tuned RF amplifier, apparently for 108 MHz, was added to beef up the sensitivity. The IF output was connected to what looks like a Hallicrafters S-30B tuned to 10.7 MHz. This fed two recorders, one connected to the voice coil of the receiver’s speaker, and the other one connected to the S-meter. The recording of the audio output was accomplished with a pivoted wooden arm. The other end held a pen which recorded on a strip of paper driven by a motor.

The recorder hooked to the meter consisted of a straw from a broom, which recorded a trace on a soot-covered cylinder turned by a wind-up alarm clock, creating a 12 hour record.

The antenna consisted of two folded dipole antennas, probably made out of TV twin lead, mounted horizontally and parallel to each other, about a hundred feet apart. With identical lengths of feed line, the signals would arrive in phase, and be identical. The antenna pattern would have a number of lobes, one of which was straight up. However, if an additional half wavelength of feedline was added to one side, the two signals would arrive out of phase. The pattern would be similar, but the signal from straight up would be nulled out. By using the difference of these two signals, the interferometer was able to null out everything but the signal from straight up. Thus, any terrestrial interference would be eliminated, and the antenna would see only the cosmic noise coming in from directly overhead.

While we think of most radio astronomy taking place at higher frequencies, there’s no reason why frequencies just above the FM broadcast band can’t be used. For example, this 2014 experiment used 38 European radio telescopes to detect radio signals from a distant galaxy on 115 MHz. Those 38 dish antennas probably provided a better signal than two folded dipoles a hundred feet apart, but they used the same principles to combine the signals.

Unfortunately, the article doesn’t give too many practical details on the construction of the set. And other than the author’s assertion that it was “relatively simple, but it works,” there’s little detail on what observations he made.

We’ve previously written about another group of students in Britain who built a radio telescope in 1959.  This website specializes in science fair projects that a student and frazzled parents can whip together in one evening, and we have many that fit that category.  Building your own radio telescope is definitely not in that category. But students were doing so 60 years ago, and there’s really no reason why an advanced student (or maybe a student who’s not so advanced, but just likes to tinker with electronics) can’t do the same thing today.



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1946 Electromatic Chairside Radio Bar

1946NovRadioRetailing3Seventy-five years ago this month, the November 1946 issue of Radio Retailing
carried this ad for the Electromatic model 609 Bar Radio. As you can see, the company sold the same style of radio-phonograph as either a chairside or tabletop model. It looks like they did a run without the phonograph, but there was a void under the lid where the phonograph was supposed to go. Who needs to listen to records if they have booze, so the logical thing to do with that spot was to turn it into a bar. The company reported that the model was selling faster than rare scotch.

You would want to be careful not to spill into the radio, although I suppose if the contents were high enough proof, they would do little other than give the chassis a good cleaning.

I’ve found references to the Model 608A and 607A, but haven’t found any evidence that any of the Model 609 Radio-Bars ever made it into production.



How to Become a DJ: 1961

1961NovBLSixty years ago this month, the November 1961 issue of Boys’ Life carried this article about what was probably the dream job of many a young man–a radio station DJ. The job meant odd hours and working weekends and holidays, but it was still a sought after position, and stations were hiring.

The author, DJ Arthur S. Harris, Jr., noted that in earlier years, the local station typically just carried network programs, with the staff announcer earning his pay merely by giving station ID. But programming was becoming local more and more, and the position of announcer often became that of DJ, spinning the records.

A few DJ’s in big cities could get salaries of over $25,000 per year, but starting pay was about $65 to $70 per week, which could probably grow to $150 a week.

To get started, the main advice was to practice. A tape recorder was an indispensible tool to record examples off the air to study, and to make practice tapes. Finally, audition tapes could be sent to radio stations. Schools and libraries might have a recorder that could be used, or a second-hand recorder could be had for about $50.



Thanksgiving: 1621-2021

"The First Thanksgiving at Plymouth" (1914) By Jennie A. Brownscombe. Wikipedia image.

“The First Thanksgiving at Plymouth” (1914) By Jennie A. Brownscombe. Wikipedia image.

Thanksgiving this year celebrates the 400th anniversary of Thanksgiving in North America. I’m somewhat appalled that nobody seems to have mentioned that the first Thanksgiving took place in 1621, 400 years ago. Clearly, it didn’t happen on the same day in November that we now commemorate. And clearly, it didn’t look much like the celebration that most of us learned about in grade school.  But we did learn about it in grade school, it was a big deal, and this is the quadricentennial.

Last year was a horrible year, and for the Pilgrims of the Plymouth Colony, 1620 was also a horrible year.  Forty-five of the 102 passengers from the Mayflower died in the winter of 1620-21.  But at the end of the following year, there was much for which they could give thanks. The harvest of 1621 was bountiful. There was peace in the land, thanks largely to a forgotten hero of American history, Squanto, an English-speaking Native American man who providentially appeared to the colonists to broker peace and teach survival.

I suppose the reason nobody talks about this anniversary is because of the way Native Americans have been treated over the following centuries. Clearly, much of that history is shameful. But the first Thanksgiving was not a part of that shameful history. The version we learned in grade school isn’t accurate in many of its details, but it is right about one thing: The colonists and the Native Americans they encountered lived in harmony. Rather than sweep this history under the rug, I think this is exactly the kind of history we should celebrate and learn from.  We shouldn’t ignore people who did the right thing 400 years ago just because other people later did the wrong thing.

Here is the account of the first Thanksgiving, written by Governor William Bradford (you can find it reprinted in this 1841 text at pages 231-33)

Our harvest being gotten in, our governor sent four men on fowling, that so we might, after a special manner, rejoice together after we had gathered the fruit of our labors. They four in one day killed as much fowl as, with a little help beside, served the company almost a week. At which time, amongst other recreations, we exercised our arms, many of the Indians coming amongst us, and among the rest their greatest king, Massasoyt, with some ninety men, whom for three days we entertained and feasted; and they went out and killed five deer, which they brought to the plantation, and bestowed on our governor, and upon the captain and others. And although it be not always so plentiful as it was at this time with us, yet by the goodness of God we are so far from want, that we often wish you partakers of our plenty.

We have found the Indians very faithful in their covenant of peace with us, very loving, and ready to pleasure us. We often go to them, and they come to us. Some of us have been fifty miles by land in the country with them, the occasions and relations whereof you shall understand by our general and more full declaration of such things as are worth the noting. Yea, it hath pleased God so to possess the Indians with a fear of us and love unto us, that not only the greatest king amongst them, called Massasoyt, but also all the princes and peoples round about us, have either made suit unto us, or been glad of any occasion to make peace with us; so that seven of them at once have sent their messengers to us to that end. Yea, an isle at sea, which we never saw, hath also, together with the former, yielded willingly to be under the protection and subject to our sovereign lord King James. So that there is now great peace amongst the Indians themselves, which was not formerly, neither would have been but for us ; and we, for our parts, walk as peaceably and safely in the wood as in the highways in England. We entertain them familiarly in our houses, and they as friendly bestowing their venison on us. They are a people without any religion or knowledge of any God, yet very trusty, quick of apprehension, ripe-witted, just. The men and women go naked, only a skin about their middles.

I encourage you to watch this short video from PBS The American Experience. This is an anniversary we ought to celebrate:

Science Fair Idea: Global Warming & Obliquity of the Ecliptic

1936NovPS1If Junior wants to perform a somewhat contrarian and controversial science fair experiment, he or she can perform an experiment to answer the following question:

“Can global warming be caused by reduction in the obliquity of the ecliptic?”

The science teacher won’t be able to react immediately, because he or she probably doesn’t know what “obliquity of the ecliptic” is. But after they consult Wikipedia, they’ll understand the concept, and they might have to grudgingly concede that there’s something to it. “Obliquity of the ecliptic” is just a fancy term for the angle at which Earth’s axis of rotation is tilted. Today, it’s about 23.4 degrees. But 8000 years ago, it was 24.2 degrees, and it’s been going down ever since.

1936NovPS2With this experiment from 85 years ago, Junior will be able to demonstrate that as the tilt decreases, the ice pack at the poles will increase. In the illustration above, the Earth is covered with “ice” to about the same extent that it is today–it’s north of the Arctic Circle. But if the tilt is increased, the extent of the ice pack covers much more of the hemisphere, as shown at left.

The experiment to demonstrate this appeared in Popular Science 85 years ago this month, November 1936. The Earth is represented by a rubber ball. A hole is drilled through the center and a knitting needle is inserted, to serve as the axis. The earth is then dipped in melted paraffin wax and covered to a depth of about 1/16 inch, representing ice. A high-wattage light bulb serves as the sun, and the ball is mounted as shown and rotated. After about a half hour, a layer of wax covers the area north of the Arctic Circle. The remaining wax drips off onto the mounting board. In the real world, this melted ice would enter the oceans.

The experiment is then repeated with a larger angle, and the “ice” covers much of the hemisphere.  Junior has demonstrated that the extent of arctic ice increases as the obliquity of the ecliptic increases, and decreases as the obliquity of the ecliptic decreases.  Since the obliquity of the ecliptic is currently decreasing, it stands to reason that this is a cause of the arctic ice decreasing.  And if the teacher believes that some other cause is at work, then he or she can come up with an experiment.  Junior can remind the teacher that this is how science works.

Make Big Money Charging Batteries: 1921

1921NovSciInvA century ago, there was big money to be made in charging batteries, and this ad in the November 1921 issue of Science & Invention told you how to get started. For just $20 down, you could purchase from Hobart Brothers Co. of Troy, Ohio, a battery charger.

The company would recommend the size of charger, from 6 to 70 batteries, to make the most money, and you could get started right away. The profits would allow you to pay the easy terms for the balance of the equipment’s price.

1962 Allied “DX’er” Regenerative Receiver Kit

AlliedDXerThe May 1962 issue of Electronics Illustrated showed this smart-looking regenerative receiver kit from Allied, the Knight Kit “DX’er”, a three-transistor regenerative receiver for the broadcast band and one shortwave band.  It operated with four penlight cells, and Allied touted the receiver as ideal for the fallout shelter.

It does seem like an ideal choice.  The set undoubtedly had a low current drain, and with a few extra sets of batteries stored away, it would probably be a good source of information for the duration of the stay.  The standard broadcast band could be used to pull in the local CONELRAD station, and the shortwaves would probably give some indication of what was going on in the outside world.

According to the magazine, the kit sold for $19.95, but in the 1963 Allied catalog, the price had been reduced to $14.95.

1921 Montgomery Ward Radio Equipment

MWStPaulA hundred years ago, Montgomery Ward was a supplier of just about everything the radio experimenter might need.  This ad appeared a hundred years ago this month in the November, 1921, issue of Radio News.

The St. Paul, MN, store with its iconic tower shown in the ad was a familiar landmark for me.  It was torn down in 1996, but for decades, it served as the distribution center in our area.  We lived in Minneapolis, and usually shopped at our local store.  But when we needed something more exotic, we knew that everything in their thick catalog would be available at that store.  Frequently, it was tires or auto parts.  We would drive to the big store, my dad would use the catalog to fill out the order form, he would hand it to the guy behind the counter, and a few minutes later, they would return with our order.  It was like having Amazon, but with immediate delivery.

 

1961 Distance Learning

1961NovRadioElecAs we’ve seen earlier, distance learning is nothing new, and sixty years ago this month, the November 1961 issue of Radio-Electronics carried a summary of the state of the art. It noted that television, either broadcast or closed-circuit, was the leading method in use at that time. The most famous was the NBC “Continental Classroom” program, which ran from 1958 to 1963, which offered college credit. While not mentioned in the article, a similar program, Sunrise Semester ran from 1957 to 1982.

And as we’ve previously covered, the article mentioned the Midwest Program on Airborne Television Instruction (MPATI), which broadcast from an airborne transmitter over much of the Midwest.

The most elaborate system in use, what we would call interactive, was that used by the New York Institute of Technology, shown above. The student listened to a recorded lesson, and then answered multiple-choice questions which were reviewed by the instructor. There was an intercom through which the student could ask questions of the instructor, and any visuals were shown to the student on a nearby TV monitor.

The magazine concluded by noting:

The exact methods that electronic instruction will follow in the future are not clear, but the question “Will it be a factor in future education?” has been answered. Make no mistake about it- electronic education is with us, and extending fast.

WW2 “Ivan The Terrible” Broadcasts

1971NovEIFifty years ago this month, the November 1971 issue of Electronics Illustrated carried the story of Ivan The Terrible, the Soviet interloper who interfered with Nazi broadcasts during the war.

Deutschlandsender broadcast its German home service on 191 kHz, with broadcasts including the news. One day in 1941, listeners were able to hear additions to the news broadcast. For example, if the announcer said, “new victories have been won by the Wehrmacht,” another voice completed the sentence with “in the grave.”

The voices were coming from Soviet Station RW-1 at Noginsk, near Moscow. The engineers at that station were able to tune the 500 kW transmitter from its original frequency of 172 kHz and synchronize it with the German station to avoid any heterodyne. Eventually, the Germans were forced to put their news broadcasts on mediumwave, and use their powerful longwave transmitter for entertainment programs.

When the Russian source of the broadcasts was known, it was dubbed Ivan The Terrible, and that name is used in this 1941 Time magazine article from September 15, 1941.

According to the 1971 Electronics Illustrated article, British and American intelligence issued a report disclosing the identity of Ivan the Terrible. Unfortunately, however, the American copy of the report was misfiled and was lost somewhere in the Washington catacombs. The British copy was still covered by the Official Secrets Act and couldn’t be made public until 1991.

But the author of the article did enough digging to give “a pretty good idea” as to the identity. According to the 1971 article, the instigator was Sololmon Abraham Lozovsy.
Despite his service to the Soviet Union, Lozovsky became the victim of one of Stalin’s purges. Even though Krushchev later issued a pardon, it came a bit too late, since Lozovsky was shot in 1952.

The actual voice of Ivan The Terrible was that of Bohemian Ernst Fischer.  After winding up on the wrong side of the Austrian civil war, he found his way to Moscow where his fluency in German was put to good use. After the war, Fischer brought his communism back to Austria, where he remained a figure in the Austrian Communist Party until 1969, serving as the Communist Minister of Information immediately after the war.

For a similar use of radio during the war, see our earlier post on Soldatensender Calais.