Tag Archives: Books

“Letters of a Radio-Engineer to His Son”

Many thanks to SWLing Post contributor, Paul, who shares a link to Letters of a Radio-Engineer to his Son by John Mills. The book, originally published in 1922, is in the public domain and shared/hosted on the Project Gutenberg website.

It is a fascinating read. Mills does a rather amazing job explaining complex electronic principles in a simple narrative form.

To give you a taste, check out Letter 3 – How a Battery Works below:


LETTER 3
HOW A BATTERY WORKS

(This letter may be omitted on the first reading.)

My Dear Boy:

When I was a boy we used to make our own batteries for our experiments. That was before storage batteries became as widely used as they are to-day when everybody has one in the starting system of his automobile. That was also before the day of the small dry battery such as we use in pocket flash lights. The batteries which we made were like those which they used on telegraph systems, and were sometimes called “gravity” batteries. Of course, we tried several kinds and I believe I got quite a little acid around the house at one time or another. I’ll tell you about only one kind but I shall use the words “electron,” “proton,” “nucleus,” “atom,” and “molecule,” about some of which nothing was known when I was a boy.

We used a straight-sided glass jar which would hold about a gallon. On the bottom we set a star shaped arrangement made of sheets of copper with a long wire soldered to it so as to reach up out of the jar. Then we poured in a solution of copper sulphate until the jar was about half full. This solution was made by dissolving in water crystals of “blue vitriol” which we bought at the drug store.

17Blue vitriol, or copper sulphate as the chemists would call it, is a substance which forms glassy blue crystals. Its molecules are formed of copper atoms, sulphur atoms, and oxygen atoms. In each molecule of it there is one atom of copper, one of sulphur and four of oxygen.

When it dissolves in water the molecules of the blue vitriol go wandering out into the spaces between the water molecules. But that isn’t all that happens or the most important thing for one who is interested in making a battery.

Each molecule is formed by six atoms, that is by six little groups of electrons playing about six little nuclei. About each nucleus there is going on a game but some of the electrons are playing in the game about their own nucleus and at the same time taking some part in the game which is going on around one of the other nuclei. That’s why the groups or atoms stay together as a molecule. When the molecules wander out into the spaces between the water molecules something happens to this complicated game.

It will be easiest to see what sort of thing happens if we talk about a molecule of ordinary table salt, for that has only two atoms in it. One atom is sodium and one is chlorine. The sodium molecule has eleven electrons playing around its nucleus. Fairly close to the nucleus there are two electrons. Then farther away there are eight more and these are having a perfect game. Then still farther away from the nucleus there is a single lonely electron.

The atom of chlorine has seventeen electrons which 18play about its nucleus. Close to the nucleus there are two. A little farther away there are eight just as there are in the sodium atom. Then still farther away there are seven.

I am going to draw a picture (Fig. 1) to show what I mean, but you must remember that these electrons are not all in the same plane as if they lay on a sheet of paper, but are scattered all around just as they would be if they were specks on a ball.

You see that the sodium atom has one lonely electron which hasn’t any play fellows and that the chlorine atom has seven in its outside circle. It appears that eight would make a much better game. Suppose that extra electron in the sodium atom goes over and plays with those in the chlorine atom so as to make eight in the outside group as I have shown Fig. 2. That will be all right as long as it doesn’t get out of sight of its own nucleus because you remember that the sodium nucleus is responsible for eleven electrons. The lonely electron of the sodium atom needn’t be lonely any more if it can persuade its nucleus to stay so close to the chlorine atom that it can play in the outer circle of the chlorine atom.

The outer circle of the chlorine atom will then have a better game, for it will have just the eight that makes a perfect game. This can happen if the chlorine atom will stay close enough to the sodium atom so that the outermost electron of the sodium atom can play in the chlorine circle. You see everything will be satisfactory if an electron can be shared by the two atoms. That can happen only if the two atoms stay together; that is, if they form a molecule. That’s why there are molecules and that’s what I meant when I spoke of the molecule as a big game played by the electrons of two or more atoms.

This molecule which is formed by a sodium atom and a chlorine atom is called a molecule of sodium chloride by chemists and a molecule of salt by most every one who eats it. Something strange happens when it dissolves. It wanders around between the water molecules and for some reason or other–we don’t know exactly why–it decides to split up again into sodium and chlorine but it can’t quite do it. The electron which joined the game about the chlorine nucleus won’t leave it. The result is that the nucleus of the sodium atom gets away but it leaves this one electron behind.

What gets away isn’t a sodium atom for it has one too few electrons; and what remains behind isn’t a chlorine atom for it has one too many electrons. We call these new groups “ions” from a Greek word which means “to go” for they do go, wandering off into the spaces between the water 20molecules. Fig. 3 gives you an idea of what happens.

You remember that in an atom there are always just as many protons as electrons. In this sodium ion which is formed when the nucleus of the sodium atom breaks away but leaves behind one planetary electron, there is then one more proton than there are electrons. Because it has an extra proton, which hasn’t any electron to associate with, we call it a plus ion or a “positive ion.” Similarly we call the chlorine ion, which has one less proton than it has electrons, a minus or “negative ion.”

Now, despite the fact that these ions broke away from each other they aren’t really satisfied. Any time that the sodium ion can find an electron to take the place of the one it lost it will welcome it. That is, the sodium ion will want to go toward places where there are extra electrons. In the same way the chlorine ion will go toward places where electrons are wanted as if it could satisfy its guilty conscience by giving up the electron which it stole from the sodium atom, or at least by giving away some other electron, for they are all alike anyway.

Sometimes a positive sodium ion and a negative chlorine ion meet in their wanderings in the solution and both get satisfied by forming a molecule 21again. Even so they don’t stay together long before they split apart and start wandering again. That’s what goes on over and over again, millions of times, when you dissolve a little salt in a glass of water.

Now we can see what happens when copper sulphate dissolves. The copper atom has twenty-nine electrons about its nucleus and all except two of these are nicely grouped for playing their games about the nucleus. Two of the electrons are rather out of the game, and are unsatisfied. They play with the electrons of the part of the molecule which is called “sulphate,” that is, the part formed by the sulphur atom and the four oxygen atoms. These five atoms of the sulphate part stay together very well and so we treat them as a group.

The sulphate group and the copper atom stay together as long as they are not in solution but when they are, they act very much like the sodium and chlorine which I just described. The molecule splits up into two ions, one positive and one negative. The positive ion is the copper part except that two of the electrons which really belong to a copper atom got left behind because the sulphate part wouldn’t give them up. The rest of the molecule is the negative ion.

The copper ion is a copper atom which has lost two electrons. The sulphate ion is a combination of one sulphur atom, four oxygen atoms and two electrons which it stole from the copper atom. Just as the sodium ion is unsatisfied because in it there is one more proton than there are electrons, so the copper ion is unsatisfied. As a matter of fact it is twice 22as badly unsatisfied. It has two more protons than it has electrons. We say it has twice the “electrical charge” of the sodium ion.

Just like a sodium ion the copper ion will tend to go toward any place where there are extra electrons which it can get to satisfy its own needs. In much the same way the sulphate ion will go toward places where it can give up its two extra electrons. Sometimes, of course, as ions of these two kinds wander about between the water molecules, they meet and satisfy each other by forming a molecule of copper sulphate. But if they do they will split apart later on; that is, they will “dissociate” as we should say.

Now let’s go on with the kind of batteries I used to make as a boy. You can see that in the solution of copper sulphate at the bottom of the jar there was always present a lot of positive copper ions and of negative sulphate ions.

On top of this solution of copper sulphate I poured very carefully a weak solution of sulphuric acid. As I told you, an acid always has hydrogen in its molecules. Sulphuric acid has molecules formed by two hydrogen atoms and one of the groups which we decided to call sulphate. A better name for this acid would be hydrogen sulphate for that would imply that its molecule is the same as one of copper sulphate, except that the place of the copper is taken by two atoms of hydrogen. It takes two atoms of hydrogen because the copper atom has two lonely electrons while a hydrogen atom only has one. It takes two electrons to fill up the game which the 23electrons of the sulphate group are playing. If it can get these from a single atom, all right; but if it has to get one from each of two atoms, it will do it that way.

I remember when I mixed the sulphuric acid with water that I learned to pour the acid into the water and not the other way around. Spatterings of sulphuric acid are not good for hands or clothes. With this solution I filled the jar almost to the top and then hung over the edge a sort of a crow’s foot shape of cast zinc. The zinc reached down into the sulphuric acid solution. There was a binding post on it to which a wire could be connected. This wire and the one which came from the plate of copper at the bottom were the two terminals of the battery. We called the wire from the copper “positive” and the one from the zinc “negative.”

Now we shall see why and how the battery worked. The molecules of sulphuric acid dissociate in solution just as do those of copper sulphate. When sulphuric acid molecules split, the sulphate part goes away with two electrons which don’t belong to it and each of the hydrogen atoms goes away by itself but without its electron. We call each a “hydrogen ion” but you can see that each is a single proton.

In the two solutions are pieces of zinc and copper. Zinc is like all the rest of the metals in one way. Atoms of metals always have lonely electrons for which there doesn’t seem to be room in the game which is going on around their nuclei. Copper as we saw has two lonely electrons in each atom. Zinc 24also has two. Some metals have one and some two and some even more lonely electrons in each atom.

What happens then is this. The sulphate ions wandering around in the weak solution of sulphuric acid come along beside the zinc plate and beckon to its atoms. The sulphate ions had a great deal rather play the game called “zinc sulphate” than the game called “hydrogen sulphate.” So the zinc atoms leave their places to join with the sulphate ions. But wait a minute! The sulphate ions have two extra electrons which they kept from the hydrogen atoms. They don’t need the two lonely electrons which each zinc atom could bring and so the zinc atom leaves behind it these unnecessary electrons.

Every time a zinc atom leaves the plate it fails to take all its electrons with it. What leaves the zinc plate, therefore, to go into solution is really not a zinc atom but is a zinc ion; that is, it is the nucleus of a zinc atom and all except two of the planetary electrons.

Every time a zinc ion leaves the plate there are left behind two electrons. The plate doesn’t want them for all the rest of its atoms have just the same number of protons as of electrons. Where are they to go? We shall see in a minute.

Sometimes the zinc ions which have got into solution meet with sulphate ions and form zinc sulphate molecules. But if they do these molecules split up sooner or later into ions again. In the upper part of the liquid in the jar, therefore, there are sulphate 25ions which are negative and two kinds of positive ions, namely, the hydrogen ions and the zinc ions.

Before the zinc ions began to crowd in there were just enough hydrogen ions to go with the sulphate ions. As it is, the entrance of the zinc ions has increased the number of positive ions and now there are too many. Some of the positive ions, therefore, and particularly the hydrogen ions, because the sulphate prefers to associate with the zinc ions, can’t find enough playfellows and so go down in the jar.

Down in the bottom of the jar the hydrogen ions find more sulphate ions to play with, but that leaves the copper ions which used to play with these sulphate ions without any playmates. So the copper ions go still further down and join with the copper atoms of the copper plate. They haven’t much right to do so, for you remember that they haven’t their proper number of electrons. Each copper ion lacks two electrons of being a copper atom. Nevertheless they join the copper plate. The result is a plate of copper which has too few electrons. It needs two electrons for every copper ion which joins it.

How about the zinc plate? You remember that it has two electrons more than it needs for every zinc ion which has left it. If only the extra electrons on the negative zinc plate could get around to the positive copper plate. They can if we connect a wire from one plate to the other. Then the electrons from the zinc stream into the spaces between the atoms of the wire and push ahead of them the electrons 26which are wandering around in these spaces. At the other end an equal number of electrons leave the wire to satisfy the positive copper plate. So we have a stream of electrons in the wire, that is, a current of electricity and our battery is working.

That’s the sort of a battery I used to play with. If you understand it you can get the general idea of all batteries. Let me express it in general terms.

At the negative plate of a battery ions go into solution and electrons are left behind. At the other end of the battery positive ions are crowded out of solution and join the plate where they cause a scarcity of electrons; that is, make the plate positive. If a wire is connected between the two plates, electrons will stream through it from the negative plate to the positive; and this stream is a current of electricity.

Pl. III.–Dry Battery for Use in Audion Circuits (Courtesy of National Carbon Co., Inc.) Storage Battery (Courtesy of the Electric Storage Battery Co.).

 


Click here to read the entire book.

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EQUINOX: A novel that blends sci-fi with ham radio

Many thanks to SWLing Post reader and author, DM Barrett (N4ECW), who recently shared the following press release which features his latest book:

FOR IMMEDIATE RELEASE

EQUINOX Blends Science Fiction And Amateur Radio

1 May 2019 (Tampa, Florida)

A new science fiction narrative, EQUINOX, has taken amateur and shortwave radio into the cultural mainstream in its version of a limited alien invasion story line.

“It’s been quite a while since the world depended on amateur and shortwave radio as lifelines. In EQUINOX, both are critical for the success of The Resistance.” – DM Barrett, EQUINOX author

DM Barrett, callsign N4ECW, lives and breathes amateur radio. He is well known in the ham radio community having developed and manufactured several different specialized radio antennas through his former company, Transworld Antennas.  He holds two earned doctorates with majors in law, economics, and religion.

The EQUINOX story line begins on a warm, slightly breezy day on Florida’s east coast as the vernal equinox marked the beginning of spring.  Suddenly, there was a thunderous crash, a blinding light, and a vortex swirling in the blue Atlantic. The invading alien army arrived. The world surrendered. The Resistance made a stand.

When the science fiction novel was recently released as a Kindle Unlimited eBook, it moved steadily into Amazon’s top ten science fiction eBooks in the United States, United Kingdom, Germany, Canada, and Australia.  After only a few days, the paperback version of EQUINOX was ranked in Amazon’s top third for science fiction paperbacks.

DM Barrett may be contacted at DMBarrettPHD@aol.com or by text to 931-239-3760.

EQUINOX and other books by DM Barrett can be ordered online through Kindle, Amazon, and Barnes & Noble.

If you are a radio amateur or shortwave enthusiast, or you are just interested in the topics, don’t miss the chance to join others that are enjoying the science fiction novel, EQUINOX.

I have been sent a paperback preview copy of Equinox and plan to read it in the coming weeks.

Equinox can be purchased from the following retailers:

Also, the author notified me that there are a limited number of paperback copies available on eBay for $14.95. These copies are a First Printing and are autographed by the author. Click here to view on eBay.

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The Cat’s Whisker – 50 Years of Wireless Design

Many thanks to SWLing Post contributor, Emilio Ruiz, who notes:

Searching archive.org found this [compilation] book: 50 Years of Wireless Design (click to view on Archive.org)

Click here to download a PDF copy.

I hope it will be interesting for you and the readers of the blog.

[The attached] cartoon is very funny… How eliminate “the hand
capacity”:

Excellent find, Elilio! Thank you for sharing!

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Book Review: “Radio Reader: Essays in the Cultural History of Radio”

Many thanks to SWLing Post contributor, Dave Kolesar, who shares the following review:

Just finished another excellent read: Hilmes and Loviglio’s collection “Radio Reader: Essays in the Cultural History of Radio.”

Very little scholarship exists about the cultural impact of radio in America, and this volume explores the history highlights (long partial list): the initial fight over the nature of broadcasting in the 1920s and 30s (educational vs. commercial), stratification of programming and channels with regards to representation of women, people of color, and gays during the Depression, WWII, and the pre-televison era, the discovery of the teenage market in the 1950s that led to the Top 40 format, the commerical Underground radio movement of the 60s, the creation of NPR and the associated decimation of student-run university stations, the rise of commercial (in everything but name) religious broadcasting and and its corrupting effects on the religious experience and political discourse, the 1980s male-dominated talk radio genre as an effort to roll back feminism, the 1996 Telecom bill and the creation of LPFM and the proliferation of pirate radio as responses to it, and finally, the digital radio future and its public service obligations.

For those who love the medium, this is a great reminder of why we work in it, how it’s succeeded and yet failed to live up to its potential, and what the future may hold as new technologies enter the audio landscape.

Thanks, Dave—sounds like this collection spans a wide variety of radio cultural histories. I did some searching and found that, of course it’s on Amazon.com, but also available used on a number of sites including Barnes and Noble.

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Free radio e-books for download

(Source: Southgate ARC)

There are a number of vintage radio and amateur radio related eBooks available for free download on the Gutenberg site

Among them is the 1922 edition of The Radio Amateur’s Handbook by A. Frederick Collins.

Jarno de Haan @PA3DMI tweeted this link that will display the books available:
http://www.gutenberg.org/ebooks/search/?query=radio

A. Frederick Collins
https://en.wikipedia.org/wiki/Archie_Frederick_Collins

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Hospitals and RF noise: FM and HD radio’s strong suit

The Sangean HDR-14 AM/FM HD radio

For the past week, I’ve been away from home spending time with my mother at the hospital while she recovers from a surgery. I’ve got a number of reviews and evaluations in the pipeline, but thankfully no shortwave or HF radios on the table this week (although the ELAD FDM-S3 and CommRadio CTX-10 are just around the corner). Listening to shortwave (or even mediumwave) in a hospital room can be an exercise in futility–there are just too many devices emitting noise and the buildings are built like bunkers with incredibly thick walls to attenuate signals.

I’ve had the little Sangean HDR-14 with me, however, and have been very pleased with its ability to snag FM stations both analog and digital. I’ve also had fun discovering a surprisingly diverse FM landscape in this metro area. I haven’t snagged an AM HD station yet, but my hope is one evening I might DX one (fingers crossed and not holding my breath).

The Sangean HDR-14 (left) and CC Skywave SSB (right)

At the end of most days, I’ve been able to catch a little shortwave action with my CC Skywave SSB (pre-production) portable at the guest house where I’m staying. The evenings have been surprisingly peaceful here with only the occasional popup thunderstorm to insert a little QRN in my listening sessions.

Last night, while listening to jazz on FM, I finished reading All The Light We Cannot See by Anthony Doerr (affiliate link).

We’ve mentioned this book before and I know of at least dozen SWLing Post contributors and friends who’ve personally recommended it to me.

It is a superb novel and will, no doubt, tug at the heart strings of any radio enthusiast or WWII history buff. Highly recommended!

Indeed, last night I couldn’t fall asleep until I finished the book around 12:30 AM!

And mom? She’s recovering quite well and we hope will be discharged from the hospital soon.

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James recommends “Seveneves” by Neal Stephenson

Many thanks to SWLing Post contributor, James Hukill (K7NEO), who writes:

So I just about wrapping up reading a new book that has morse code mentioned as a part of the plot in darn near 80% of the book. Well and not in a cheese demeaning way.

[Stephenson] is one of my favorite authors and popular enough to not be obscure to most folks.

Anyways, thanks for all your hard work.

My pleasure, and thank you for the book recommendation, James! I read through the synopsis and–being a sci-fi and dystopia fan–it does sound like a fascinating read indeed! Putting this on my wishlist.

Click here to view on Amazon.com (affiliate link).

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