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Saturday, September 12, 2015

Claude Shannon had The Knack (video)





From Wikipedia:
Shannon showed an inclination towards mechanical and electrical things. His best subjects were science and mathematics, and at home he constructed such devices as models of planes, a radio-controlled model boat and a wireless telegraph system to a friend's house a half-mile away. While growing up, he also worked as a messenger for the Western Union company.
His childhood hero was Thomas Edison, whom he later learned was a distant cousin. Both were descendants of John Ogden (1609–1682), a colonial leader and an ancestor of many distinguished people. 


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And he he was part of a scheme to beat Vegas at the roulette wheel through the use of what may have been the first wearable computer: 
http://www.engadget.com/2013/09/18/edward-thorp-father-of-wearable-computing/


An excerpt from that site: 
After their initial meeting, Thorp says, "we got right to it," and he spent about half his time for the next eight months working away with Shannon in that basement lab in Shannon's house, on one of Massachusetts' Mystic Lakes. In his paper, Thorp described the lab as a "gadgeteer's paradise," with what he estimated to be about a hundred thousand dollars' worth of electronic, electrical and mechanical items. The regulation roulette wheel, ordered from Reno for $1,500, was set up on an old slate billiard table.
Thorp describes Shannon as the "ultimate gadgeteer," and recalled in his paper that the man he met in that office was a "thinnish alert man of middle height and build, somewhat sharp-featured," and that "his eyes had a genial crinkle and the brows suggested puckish incisive humor." That humor would become evident as the two worked together at the house on the lake. Thorp wrote that Shannon taught him to juggle three balls, and that he rode a unicycle on a steel cable strung between two tree stumps. "He later reached his goal," he wrote, "which was to juggle the balls while riding the unicycle on the tightrope."
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Friday, September 11, 2015

Kids Homebrewing in Japan in the 1920s

Michael Rainey's photo.
 
Michael Rainey, AA1TJ, Poet Laureate of QRP and Wizard of the Vermont Hobbit Hole found this drawing and put it on his face book page.  It is clearly supportive of the "International Brotherhood of Electronic Wizards" theme of this blog, so I have shamelessly expropriated it.  All for the cause Michael!   I hope this indicates that OM AA1TJ is emerging from a too-long spate of radio-inactivity. 
 
Michael says the drawing is from the 1920's children’s magazine, "Kodomo No Kuni" by Kiichi Okamoto.  David Cowhig, WA1LBP, provides this translation:
 
Title "Ni-chan,  I can hear it!"
The radio kid is saying something like:
-- Wait, no I lost it.
-- uhhhh
-- I can hear it, I can hear it, I've got it!
 
David notes: Sometimes Japanese use the katakana syllabary to add emphasis like we might with italics or exclamation points. 
 
Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Thursday, September 10, 2015

Kon-Tiki and the Gibson Girl



Back in July we shared a very nice video sent to us by Rupert G6HVY on the radios used by the Kon-Tiki expedition.  Many of us had questions about the device used by the intrepid radio operator to generate hydrogen gas (for the antenna balloon) while on the high seas.   Mike Herr WA6ARA supplied the answer:   1200 grams of Calcium Hydride crystals.  This was part of the WWII rescue  radio set CRT-3 (aka the Gibson Girl). 

Fair Radio Sales occasionally sells this intriguing device: 
https://www.fairradio.com/catalog.php?mode=search&keywords=hydrogen&submit.x=21&submit.y=8

And here is great site with more details on the other antenna supports in the Gibson Girl set, including a ROCKET LAUNCHED KITE! 

https://billboyheritagesurvey.wordpress.com/2012/01/17/war-kite-the-gibson-girl-kites/

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Tuesday, September 8, 2015

Speaking of Breadboards...




Clint KA7OEI sent us these inspiring photos of his 10 GHz transverters.  FB Clint!  The one on the top was built in 2005 and STILL looks like this.  Note "CAT" component in the version pictured in the second photo.


Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Monday, September 7, 2015

Si5351 and the Spectral Purity Mask


I was thinking about spectral purity standards and the Si5351 chip. I realized that I didn't even know what the FCC standards for "close in" noise are.   The standards for spurious emissions ARE well known, but these are for harmonics and parasitic emissions relatively far from the desired signal.  What about unwanted signals CLOSE to the desired signal? 

My old 2002 ARRL handbook indicates that the FCC has not established firm standards for this "close in" noise.  (They call it "out of band" noise, but are clearly referring to noise that is close to the desired signal but spreading out beyond the desired bandwidth.  Phase noise would be in their category.)

In the course of my Googling, I found the above spectral purity mask.   I don't know where it comes from, but I think it is the kind of graph that would be very useful to us as we evaluate the merits and shortcomings of various frequency synthesizers.  Would our DDS or PLL rigs fit in this mask?   I think an Si5351 rig WOULD.  According to KE5FX's measurements, at a mere 100 Hz from the center frequency, the Si5351 phase noise is already -90 db.

Does anyone have a similar mask showing current standards?

I still don't understand why so many folks believe that the Si570 is a useful part for homebrew rigs, but the Si5351 is not.  Look at the numbers:

Si570
Clifton Labs  measuring at 30 MHz carrier. At 10kHz from carrier:   -109.6 dbc/Hz
Silicon Labs web site (carrier freq not specified) At 10 kHz from carrier:  -116 dbc/Hz

Si5351
KE5FX measuring at 19.99 MHz. At 10kHz from carrier:  -127 dbc/Hz
Silicon Labs  measuring at 156.2 MHz. At 10 kHz from carrier   -112 dbc/Hz.

Can anyone out there explain the technical basis for the belief that the Si570 is a useful part while the Si5351 is not?   

It is important to keep things in perspective.  ALL of these noise numbers represent VERY small noise levels.   Let's keep is simple and assume a 100 watt carrier signal and a phase noise of -100 dbc/Hz.   That means the phase noise per hertz would be .00000001 watts.  That's watts/hertz.  How much "noise power" would that represent in a typical SSB passband?  Multiply by 2500 Hz and you get 25 microwatts.  That's really low noise levels. Not enough to worry about.  And as we've noted, we've happily used rigs with LC VFOs and crystal oscillators for all these years without every once measuring their phase noise.

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Saturday, September 5, 2015

Alan Wolke's Drake 2-B (video)



Alan's video inspired me to do a little work with my Drake 2-B.  Nothing major -- I was just making sure that the passband knob is in the right setting.  I've complained that the Drake 2-B doesn't sound great on AM.  I recently noticed that my BITX40 DIGI-TIA sounds surprisingly good with AM signals -- I just treat them as SSB signals and zero-beat the carrier with my Si5351 VFO.  I wanted to try doing the same thing with the 2-B, and then make some comparisons.  I only heard a few AM signals this morning, so I will try again later today and will report results here.   

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Thursday, September 3, 2015

Breadboarding and Mountaintopping


We needed an illustration today.  I was having trouble finding something suitable.  Then the Radio Gods (along with Joe Peltola and the artist N0UJR) provided this.  Obviously I can relate to the breadboard operation. I'm sure Pete can too.  As for the mountain topping, that made me think of Colin, M1BUU.  And of Wes, W7ZOI.

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Five Lessons from Pluto for Homebrewers

http://www.edn.com/electronics-blogs/embedded-basics/4440230/5-Engineering-Lessons-from-Pluto?_mc=NL_EDN_EDT_EDN_today_20150901&cid=NL_EDN_EDT_EDN_today_20150901&elq=3e27f3c4018844db9381c8a508867555&elqCampaignId=24586&elqaid=27842&elqat=1&elqTrackId=06ba9f8cc21140c1ae477df75c36dd65

Thanks to Bob Crane, W8SX, for the link to this article.   Those of us who are reading "The Martian" will find the mention of RTG power interesting (but hey, let's not try to put any plutonium in our rigs, OK?) 

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Wednesday, September 2, 2015

Interview with Paul Horowitz (W1HFA) -- A Giant In Radio Electronics (Video)



I've been hearing about this book for years, but until I watched this interview, I knew nothing about the author.  Thanks Lady Ada.  (And thanks to Farhan for the alert.) 

As a native New Yorker, I'm pleased to include in the blog yet another reminder that the Big Apple is not all fashion and finance -- a lot of solder has been melted in my home town. 

Paul Horowitz has a truly awesome bio.   He got his ham license at age eight.  QST tells us that lots of little kids do this, but unlike some of the youngsters we see in the magazine I suspect young Paul really mastered the theory.  Paul Horowitz has "The Knack."  Big time.

PhD from Harvard.   Author of "The Art of Electronics."  Pioneer in the Search for Extraterrestrial Intelligence.  Carl Sagan is believed to have  modeled the main character in "Contact" partly on Paul.  Check out the wiki  page:

https://en.wikipedia.org/wiki/Paul_Horowitz

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20
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