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Wednesday, November 6, 2013
Zoltan Bay and his Chemical Moonbounce Detector
In March 1944, Bay recommended using the radar for scientific experimentation, including the detection of radar waves bounced off the Moon. The scientific interest in the experiment arose from the opportunity to test the theoretical notion that short wavelength radio waves could pass through the ionosphere without considerable absorption or reflection. Bay's calculations, however, showed that the equipment would be incapable of detecting the signals, since they would be significantly below the receiver's noise level.
The critical difference between the American and Hungarian apparatus was frequency stability, which DeWitt achieved through crystal control in both the transmitter and receiver. Without frequency stability, Bay had to find a means of accommodating the frequency drifts of the transmitter and receiver and the resulting inferior signal-to-noise ratio. He chose to boost the signal-to-noise ratio. His solution was both ingenious and far-reaching in its impact.
Bay devised a process he called cumulation, which is known today as integration. His integrating device consisted of ten coulometers, in which electric currents broke down a watery solution and released hydrogen gas. The amount of gas released was directly proportional to the quantity of electric current. The coulometers were connected to the output of the radar receiver through a rotating switch. The radar echoes were expected [11] to return from the Moon in less than three seconds, so the rotating switch made a sweep of the ten coulometers every three seconds. The release of hydrogen gas left a record of both the echo signal and the receiver noise. As the number of signal echoes and sweeps of the coulometers added up, the signal-to-noise ratio improved. By increasing the total number of signal echoes, Bay believed that any signal could be raised above noise level and made observable, regardless of its amplitude and the value of the signal-to-noise ratio.26 Because the signal echoes have a more-or-less fixed structure, and the noise varies from pulse to pulse, echoes add up faster than noise. From: http://history.nasa.gov/SP-4218/ch1.htm
During the war, Zoltán Bay protected Jewish colleagues from Nazi persecution. In 1998, the State of Israel honored him as Righteous Among the Nations for his actions and listed his name at Yad Vashem.
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Labels:
EME,
Hungary,
moonbounce
Monday, November 4, 2013
SolderSmoke Podcast #156 -- Special Echolink Interview
http://soldersmoke.com/soldersmoke156.mp3
Special hour-long interview with Peter Parker, VK3YE
-- Early experiences with radio
-- CW
-- DSB Gear
-- Simple gear, and gear that is TOO simple
-- VXOs, Super VXOs and Ceramic Resonators
-- Building receivers
-- Chips vs. Discrete
-- Making the leap to SSB
-- The Knob-less wonder and the BITX
-- No need for a sophisticated workshop
-- Advice for new phone QRPers
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
Labels:
Australia,
BITX20,
DSB,
Parker--Peter,
SolderSmoke Podcast,
SSB
Sunday, November 3, 2013
BITX Build Update #18 -- BITX in a Box?
I've really been enjoying using my BITX17 without an enclosure. Having all the electronics exposed on the workbench really accentuated the homebrew nature of this rig. But obviously it was time to box this thing up. At a local craft store, I found a wooden box that is exactly the right size for my BITX copper clad board. I put the BITX in the box yesterday. I kind of miss the exposed electronics.
The far left control is AF gain. The need for a few inches of wire to the pot has introduced a bit of AC hum. I'll try to knock this down with better shielding on the lead to the pot.
But this gets brings us too a bigger question: the need for a cabinet that shields. Obviously the wood shields it only from dust. I know there are some benefits to putting this thing in a proper metal box. The AC hum would be less of a problem. Also -- listen to this -- in the morning, before 17 opens, I can hear -- faintly -- the WWV transmission on 5 MHz (recall that the IF in this rig is 5 MHz). And if I ever build an external linear amp for this rig (I might), I guess a proper metal box would help prevent the kind of oscillation that often drives me crazy on these kinds of projects.
So, what do you guys think? Stick with the wood, or put it in a metal box? Any thoughts on putting metal shielding material around the inside of the box (thick aluminum of tin foil)?
(The other black control knob is for a rotary switch that will allow me to select among two or three crystals for the VXO. )
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Labels:
BITX20
Saturday, November 2, 2013
40% Off SolderSmoke Book!!! Through 4 November
And on all Lulu books.
Just use the coupon code FALLSALE40 at checkout.
http://www.lulu.com/spotlight/soldersmoke
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
Just use the coupon code FALLSALE40 at checkout.
http://www.lulu.com/spotlight/soldersmoke
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
Arecibo Birthday
Thanks to Bob Crane for this birthday alert:
The
Arecibo Observatory opened on this date in 1963. At a diameter of
a thousand feet, it's the largest single-aperture telescope ever built. It's
also got the largest focusing dish in the world, which gathers electromagnetic
waves from space. Located near the city of Arecibo in Puerto Rico, it's close to
the equator, which enables it to "see" (via radio waves) all the planets in the
solar system; within six months of its opening, it enabled scientists to study
the rotation rate of Mercury and determine that it rotated every 59 days, rather
than 88 as was previously thought. It's also been used for military purposes
like locating Soviet radar installations by tracking their signals as they were
reflected off the moon. It's provided the first full imaging of an asteroid and
also led to the first discovery of planets outside our solar system.
In 1999, it began collecting data for the SETI
Institute; SETI stands for "search for extraterrestrial intelligence," and the
organization looks for deliberate radio or optical signals from other planets.
The Arecibo Observatory also sends data over broadband to the home and office
computers of 250,000 volunteers, who, through the Einstein@Home program, donate
their computers to be used for data analysis during periods when they would
otherwise be idle. A year ago, three such volunteers in Iowa and Germany
discovered a previously unknown pulsar, 17,000 light years from
Earth.
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
Labels:
radio astronomy,
SETI,
telescopes
Thursday, October 31, 2013
Brooklyn Bike Generator -- Want one!
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
Labels:
bicycle,
Emergency Power
Wednesday, October 30, 2013
The New "Gold Standard" in QRSS Grabbers
Bill
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
I just discovered Scott Harden's "QRSS Plus" grabber aggregator...
Check it out - it is the new "Gold Standard".
73, Paul
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
Labels:
QRSS
An Interesting Idea for Checking Crystal Filter Passbands
Today at 9:37 AM
Hi Bill,
Just listened to your last soldersmoke blog with reference to xtal filter checking using a DDS and scope. What do think of this idea to check filter performance?
Logical, relatively easy to build and NO digital electronics to deal with.
Best 73
Rick G6AKG
PS keep up the great work, love the Blogs.
Labels:
test gear
Monday, October 28, 2013
Slide Show of BITX 17 Build
As I was building this rig, I periodically stopped and took a picture of the board. I think the resulting slide show is kind of fun. Check it out: There is a button to launch the slide show.
http://www.flickr.com/photos/106886073@N04/sets/72157637045750216/
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
http://www.flickr.com/photos/106886073@N04/sets/72157637045750216/
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
Labels:
BITX20
Book Review: "Bunch of Amateurs" by Jack Hitt
The title held a lot of promise, but the subtitle ("A Search for the American Character") hinted at the main problem that I had with the book: the author (perhaps driven by his editor) seemed to be struggling to prove that there is some uniquely American elements to amateur science and technology. Early on, Mr. Hitt, makes the preposterous claim that "the rest of the world doesn't have amateurs." He goes on to write that "In Europe and on other continents, the word hints at class warfare... Amateurs may be taken seriously, but, almost by the power of the word, are kept in their place: isolated outside some pre-existing professional class, some long-standing nobility. In America, amateurs don't stay in their place or keep to themselves."
What a load of rubbish! This claim directly contradicts what many of us have been finding out in the quintessentially amateur world of amateur radio: as we travel around the world (in person, or via the ionosphere) we find, all around the globe, guys who have followed shockingly similar paths to ham radio. From Sudan to Switzerland, from India to Indiana, the story is much the same. And I'll bet you'll find similar similarities in just about every serious sci-tech hobby (astronomy, photography, etc.). To claim that there is something fundamentally exceptional about amateurism in the U.S. is, I think, ridiculous. Mr. Hitt should have spent some time looking at the amazingly diverse and vibrant world of British amateur science and technology. That alone would have prevented him from straying into these silly claims of American amateur exceptionalism.
But, all that aside, there is a lot of interesting material in the book. I liked his description of John Dobson and the amateur telescope builders. And, somewhat surprisingly, Hitt's description of the DIY Biology movement (these guys are playing with genetics and cooking up new organisms) seemed to capture very well the creative joy and satisfaction that amateurs find when working (just for fun) on their projects. I was kind of surprised when I found myself identifying with the DIY Biology folks. Their basement labs sounded a lot like our radio shacks.
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
What a load of rubbish! This claim directly contradicts what many of us have been finding out in the quintessentially amateur world of amateur radio: as we travel around the world (in person, or via the ionosphere) we find, all around the globe, guys who have followed shockingly similar paths to ham radio. From Sudan to Switzerland, from India to Indiana, the story is much the same. And I'll bet you'll find similar similarities in just about every serious sci-tech hobby (astronomy, photography, etc.). To claim that there is something fundamentally exceptional about amateurism in the U.S. is, I think, ridiculous. Mr. Hitt should have spent some time looking at the amazingly diverse and vibrant world of British amateur science and technology. That alone would have prevented him from straying into these silly claims of American amateur exceptionalism.
But, all that aside, there is a lot of interesting material in the book. I liked his description of John Dobson and the amateur telescope builders. And, somewhat surprisingly, Hitt's description of the DIY Biology movement (these guys are playing with genetics and cooking up new organisms) seemed to capture very well the creative joy and satisfaction that amateurs find when working (just for fun) on their projects. I was kind of surprised when I found myself identifying with the DIY Biology folks. Their basement labs sounded a lot like our radio shacks.
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
Labels:
books,
telescopes,
UK
Saturday, October 26, 2013
BITX BUILD UPDATE #17 Arv's Discrete AF AMP
I've been kind of cheating with the audio output from my BITX17: I've been using one of those little battery-powered computer speakers. It sounded fine, but hey, this is supposed to be a homebrew project right? I've already noted my ideological objections to the use of the LM386 CHIP. The files of the BITX20 yahoo group provided a very promising and completely discrete AF amp circuit by Arv Evans, K7HKL. I used a 2N3906 and a 2N3904, with a 2N2222 driving them. It works like a charm. Not a bit of feedback or motor-boating. It sounds great. I've already had a contact with it: Jack, W7YUM is a builder of big amplifiers out in Salt Lake City. He seemed very impressed with the BITX concept so we may have a Utah BITX in the works.
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
Labels:
BITX20
Friday, October 25, 2013
Words of Wisdom (on Amplifier Stability)
From "A Simple SSB Transceiver" by Ashhar Farhan:
"What if your transmitter is unstable? Don't curse your fate. All transmitters start out as unstable beasts. Relax." Farhan goes on to provide some good pointers on how to tame the beast.
I've had very good luck with the PA in the BITX -- very little cursing of fate on this project.
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
"What if your transmitter is unstable? Don't curse your fate. All transmitters start out as unstable beasts. Relax." Farhan goes on to provide some good pointers on how to tame the beast.
I've had very good luck with the PA in the BITX -- very little cursing of fate on this project.
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
Labels:
Farhan,
troubleshooting
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