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PostPosted: Mon Nov 23, 2015 3:26 pm 
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Off topic, but I believe we have a few radio amateurs in the audience.

From a hackaday article on spark gaps and coherers, two old radio books you can read online:

- Radio simplified; what it is–how to build and operate the apparatus
by Kendall, Lewis F., jr.; Koehler, Robert Philip, joint author
Published [c1923]

- Wireless Telegraphy its history, theory and practice
by A Fredrick Collins
Published in 1905

Also a couple of specific papers on spark gaps and coherers:
- On the Action of the Coherer
by Wheeler, E. B.
Published April 28, 1899

- A Self-Readjusting 'Coherer.'
by Lawrence, A. E.
Published December 9, 1898

And one more:
- The work of Hertz and some of his successors
by Lodge, Oliver, Sir
Published 1894


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PostPosted: Mon Nov 23, 2015 4:37 pm 
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Thanks Ed.

It was interesting to read the first chapter of 'Wireless telegraphy', published in 1905. The chapter discusses the Ether (or Aether). I didn't know that about 200 years earlier, the existence of the Ether had been rejected by one Father Boscovitch. And then continuing to explain that the experiments of Faraday, Maxwell, and Hertz in fact proved that the Ether exists ("settled conclusively and finally the existence of an ether"), and Boscovitch' notion could be rejected. The discussion in the book is quite detailed, going over many pages. What's strange, of course, is that the book was published in 1905, and the Michelson-Morley experiment which did not find an Ether was performed in 1887. And it had been repeated with increasing sensitivty (according to Wikipedia) since, including in 1902 and 1905 (which is a significant year in so many ways). So just when the Ether theory was apparently at its most solid ever, among some physicists, it crashed headfirst into a wall and had to be rejected.

In many ways the Ether discussion reminds me of today's dark matter and dark energy theories.. not that they will necessarily suffer the same fate, but it's like deja-vu to read about the aether/ether in that chapter of this book.

-Tor


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PostPosted: Mon Nov 23, 2015 4:48 pm 
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Interesting point! We do tend to grab at ideas and hold onto them, but research moves on and a new generation may come up with a much better fit.


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PostPosted: Mon Nov 23, 2015 6:21 pm 
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This is very O.T., but I might be able to help remedy that by saying a lot of radio amateurs use Commodore 64's to control radio equipment, calculate the direction their antenna should point, do Morse code, etc..  :D   I'm a ham myself, but have not been "radioactive" since the C64 had its heyday.  I got into it in the 1970's, and I remember drooling over what was the Cadillac of equipment back then, the Rockwell Collins stuff from years earlier that was still holding its own in spite of Kenwood and a few other fine manufacturers.

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That Collins equipment was about as far back in history as my interest went.  Being a teenager at the time, my budget was limited, so I bought a rather low-priced but decent HF receiver from Heathkit, the HR-1680

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(the readability of the meter and dial in red were much better than the picture lets on) and built myself a single-tube (6AQ5) CW transmitter from a schematic in a magazine article.  I got a lot of compliments on the sound of that transmitter.  Later I bought the much smaller Heathkit HW-8 QRP CW transceiver

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and modified it heavily, adding a lot of capabilities it didn't come with.  I had a lot of fun with that.  I got to where I could take the code at about 30wpm while looking through a magazine for an article I was discussing with the other person, and get most of both.

I did a job in Spain in 1989 and some engineers there asked me to bring them a product made by a home business called Engineering Consulting that made equipment to facilitate using your C64 to control your repeater and other ham equipment.  I went to the man's house to pick up what I was to take to Spain.  He had most of the rooms of this large, 2-story house set up for various aspects of the business—assembly, warehouse, engineering, accounting, etc., employing family members.  It was pretty impressive.

I have been maintaining my license, but have not been on the air since we got married 31+ years ago, because we spent our first seven years of marriage in an apartment that did not allow antennas.  A friend tried to get me interested in VLF, where you can use a very limited amount of power on around 170kHz without a license.  (I guess it's not even a ham band, but you can tinker with it anyway.)  It was amusing to think I could do a software-defined radio with my 6502 workbench computer, and use an audio amplifier IC to feed the antenna!  :lol:

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PostPosted: Tue Nov 24, 2015 10:55 pm 
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Here's a Carver Mead link; He's "picked a fight" with Einstein!

1. https://www.youtube.com/watch?v=CnwX2IF46m0 "Carver Mead presents The Universe and Us: An Integrated Theory of Electromagnetics and Gravitation"


Also, Michelson, Mr. "Ain't-no-such-thing-as-ether" man, himself, had a computer (analog!).

2. https://www.youtube.com/watch?v=NAsM30MAHLg&list=PL0INsTTU1k2UYO9Mck-i5HNqGNW5AeEwq "Albert Michelson's Harmonic Analyzer: (1/4) Intro/History: Introducing a 100-year-old mechanical computer"

3. https://www.youtube.com/watch?v=8KmVDxkia_w&list=PL0INsTTU1k2UYO9Mck-i5HNqGNW5AeEwq "(2/4) Synthesis: A machine that uses gears, springs and levers to add sines and cosines" (and two more)

I still have to listen to the "Mead" thing again--with a fine toothed comb---though I just broke my metaphor, as combs are rarely known for their listening capabilities ... (Interdigitated "comb filter" .... hmmmm .... maybe... I studied SAWs once or twice; Surface Acoustic Wave Transducers. A bit "over my head', but what isn't, in this field! Maybe those "combs" do something like "listening"?)

I should also (1) see some old Mead vids and (2) try to read a couple things he wrote. (I did see a panel discussion vid with just him and Gordon Moore, discussing Moore's law; interesting that these old friends exchanged a couple of 4004s for the simple pleasure of conversation! I guess Mead's bona fides are legit! I rarely read, much about him, and only know what I read in Gilder's book--which I intensely distrusted, for various reasons; political, religious, philosophical, and scientific--"The Silicon Eye".).


Last edited by randallmeyer2000 on Sat Nov 28, 2015 4:29 am, edited 1 time in total.

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PostPosted: Tue Nov 24, 2015 11:04 pm 
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[Another mistake on my part, intended to send a PM]


Last edited by BigEd on Wed Nov 25, 2015 10:17 am, edited 1 time in total.

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PostPosted: Tue Nov 24, 2015 11:49 pm 
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That machine is amazing, as are so many of the mechanical marvels that came along before computers. Taking its input from an array filled from an 8-bit A/D converter, my 5MHz 65c02 workbench computer does a 2048-point complex FFT in five seconds in Forth (not even assembly), approximately a hundred times as fast as the original IBM PC did a complex FFT of half that many points in GWBASIC, and of course some other processors can do it a thousand times as fast or faster. We have it so easy today.

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