A question this morning from Scott KQ4AOP caused me to Google this old book On page 59 I found the article about my first transmitter. Someone has put a copy of the entire book on the interenet. Here it is:
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Showing posts with label books. Show all posts
Showing posts with label books. Show all posts
Monday, September 16, 2024
Monday, February 5, 2024
"The Soul of a New Machine" -- Re-reading the Classic Book by Tracy Kidder
This book is especially important to the SolderSmoke community because its title has led to one of the most important concepts in our community and our lexicon: That we put "soul" in our new machines when we build them ourselves, when we make use of parts or circuits given to us by friends, or when we make use of parts (often older parts) in new applications. All of these things (and more) can be seen as adding "soul" to our new machines. With this in mind I pulled my copy of Tracy Kidder's book off my shelf and gave it a second read. Here are my notes:
-- On reading this book a second time, I found it kind of disappointing. This time, the protagonist Tom West does not seem like a great person nor a great leader. He seems to sit in his office, brood a lot, and be quite rude and cold to his subordinate engineers. Also, the book deals with a lot of the ordinary stupid minutia of organizational life: budgets, inter-office rivalry, office supplies, broken air conditioners. This all seemed interesting when I read this as a youngster. But having had bosses like West, and having lived through the boring minutia of organizational life, on re-reading the book I didn't find it interesting or uplifting.
-- The young engineers in the book seem to be easily manipulated by the company: They are cajoled into "signing up" for a dubious project, and to work long (unpaid) hours on a project that the company could cancel at any moment. They weren't promised stock options or raises; they were told that their reward might be the opportunity to do it all again. Oh joy. This may explain why West and Data General decided to hire new engineers straight our of college: only inexperienced youngsters would be foolish enough to do this. At one point someone finds the pay stub of a technician. The techs got paid overtime (the engineers did not), so the techs were making more money than the engineers (the company hid this fact from the engineers). The young engineer who quit probably made the right move.
-- The engineers use the word "kludge" a lot. Kidder picks up this term. (I'm guessing with the computer-land pronunciation that sounds like stooge.) They didn't want to build a kludge. There is one quote from West's office wall that I agree with: "Not everything worth doing is worth doing well." In other words, don't let the perfect be the enemy of the good. Sometimes a kludge will do.
-- Ham radio is mentioned. One of Wests lead subordinates was a ham as a kid. Kidder correctly connects this to the man having had a lonely childhood. Heathkit is also mentioned once, sarcastically.
-- The goal itself seems to be unworthy of all the effort: They are striving to build a 32 bit computer. But 32 bit machines were already on the market. The "New Machine" wasn't really new.
-- Kidder does an admirable job in describing the innards of the computer, but even as early as the 1978 models, I see these machines as being beyond human understanding. The book notes that there is only one engineer on the hardware team who has a grasp of all of the hardware. The software was probably even more inscrutable.
-- I found one thing that seemed to be a foreshadowing of the uBITX. The micro code team on this project maintained a log book of their instructions. They called it the UINSTR. The Micro Instruction Set. Kidder or the Microkids should have used a lower-case u.
-- The troubleshooting stories are interesting. But imagine the difficulties of putting the de-bugging effort in the hands of new college graduates with very little experience. I guess you can learn logic design in school, but troubleshooting and de-bugging seem to require real-world experience. We see this when they find a bug that turns out to be the result of a loose extender card -- a visiting VP jiggled the extender and the bug disappeared.
-- Kidder provides some insightful comments about engineers. For example: "Engineering is not necessarily a drab, drab world, but you do often sense that engineering teams aspire to a drab uniformity." I think we often see this in technical writing. Kidder also talks about the engineer's view of the world: He sees it as being very "binary," with only right or wrong answers to any technical question. He says that engineers seem to believe that any disagreement on technical issues can be resolved by simply finding the correct answer. Once that is found, the previously disagreeing engineers seem to think they should be able to proceed "with no enmity." Of course, in the real world things are not quite so binary.
-- This book won the Pulitzer prize, and there is no doubt about Kidder being a truly great writer, but in retrospect I don't think this is his best book. This may be due to weaknesses and shortcomings of the protagonist. I think that affects the whole book. In later books Kidder's protagonists are much better people, and the books are much better as a result: for example, Dr. Paul Farmer in Kidder's book Mountains Beyond Mountains.
-- Most of us read this book when we were younger. It is worth looking at again, just to see how much your attitudes change with time. It is important to remember that Tracy Kidder wrote this book when he was young -- I wonder how he would see the Data General project now.
-----------------------
Here is a book review from the New York Times in 1981:
https://archive.nytimes.com/www.nytimes.com/books/99/01/03/specials/kidder-soul.html?CachedAug
Here's one about a fellow who also re-read the book and who provides a lot of good links:
https://auxiliarymemory.com/2017/01/06/rereading-the-soul-of-a-new-machine-by-tracy-kidder/
Saturday, January 20, 2024
K0IYE's Thoughts on Homebrewing and Workshops
Click on the image for a clearer look
I like Frank Harris K0IYE's book so much that I don't mind posting about it frequently. "From Crystal Sets to Sideband" is must-read material for all homebrewers.
The picture above is especially significant. I first came across it in the old pulp-style magazine called World Radio. The picture, like Frank's book, is truly inspiring.
This week I stumbled across a relatively new chapter in Frank's book. Chapter 3A deals with his approach to homebrewing (Luddite, analog, HDR) and his advice on how to set up a home ham-radio workshop. There is a lot of wisdom in this chapter.
The opening paragraph of Chapter 3A really grabbed me. Check it out here. Click on the text below for a better view:
Click on the image above for an easier read
Frank's advice on what to do when you get stuck on a problem is right on the mark, and a bit counterintuitive, but very true: Do something else for a while.
Click here for all of Chapter 3A:
Chapter 3B also looks great.
And click here for the entire book (including a Spanish translation!)
Sunday, December 17, 2023
Make Your Own SDR Software! And, "Analog Man" by Joe Walsh of the Eagles (WB6ACU)
The above video appeared on Hack-A-Day this morning. ON THE SAME MORNING, Bruce KK0S happened to send me this version of Joe Walsh WB6ACU's song "Analog Man." This version has the lyrics. Thanks Bruce.
I am currently struggling with some DNS server problems. Dean KK4DAS is helping me. In spite of many years on the internet, this DNS problem has reminded me that, like Joe Walsh, I am an analog man. I mean, just take a look at my Mythbuster rig: (1382) Mythbuster for Lamakaan ARC - YouTube
But there are limits to my analog fanaticism. First, while Joe proclaims that he is looking for an analog girl, I very luckily found a digital girl. Elisa is quite digital. Second, even though digital tech is not my thing, I am willing to accept its usefulness. I mean, there is so much we wouldn't be doing if we were all "analog men." Like going to the moon.
This is a hobby -- it is all for fun. Whatever floats your boat, right? Still, Joe's song reminds me a bit of the old "SPARK FOREVER!" that you can still see on old QSL cards. That's kind of sad. I just recognize that my comfort zone is more analog than digital.
Friday, November 24, 2023
A FREE Book from the Early Days of Ham Projects with Transistors: The CK722 -- The Device that Got Pete Juliano Started in Homebrew
Pete N6QW sent this amazing book to me this morning. Pete wrote:
"The book was the size of a Notebook and had a gray cover. I built some of the projects like the CPO. If you had a CK722 then you were there."
You can get the book for free here:
The impact of the CK722 on Pete Juliano, on ham radio, and eventually on SolderSmoke was quite profound. Back in 2015, I wrote about this on the blog:
I knew Pete had a lot of experience with transistors, but I didn't realize just how far back this experience reaches. Pete writes, "The March 2015 issue of QST had an article about a 1953 transistor transmitter project which was really advanced technology since the transistor was only invented about 5 years before that time... About 1953 at the age of 11, I built my first solid state audio amplifier using the venerable CK722 from Raytheon. The transistor did look a bit strange in that cool blue cube shape with a red dot on the side to identify the collector. What a joy and surprise to me that it worked the first time power was applied... It was the CK722 that in large measure started me on a life’s work and engagement in a wonderful hobby. That CK722 path also led me to designing and building a QRP solid state version of the Collins KWM2 which I call the KWM-4." I asked Pete why an 11 year-old kid in 1953 felt compelled to build a solid state audio amp. The answer is very cool: Pete's father had introduced him to crystal radios at age 8. Pete wanted an amplifier for his crystal set, but his dad was worried about him building high voltage tube gear. So that's how Pete got his VERY early start with transistors.
We are really lucky to have Pete Juliano sharing his vast tribal knowledge with us.
We are really lucky to have Pete Juliano sharing his vast tribal knowledge with us.
----------------
You can see a complete set of SolderSmoke posts about the CK722 here:
Wikipedia has a nice article on the CK722. The design contest Raytheon sponsored would be the kind of contest we could really get into! https://en.wikipedia.org/wiki/CK722
Thanks Pete. And thank you Raytheon!
Friday, November 10, 2023
SolderSmoke Podcast #249 -- Travel, Pete's 6BA6 rig, Books!, VFOs, SDR, Computers, Spectrum Analysers, Transistor Man! MAILBAG
New VFO for 15-10 Transceiver
Schematic below
SolderSmoke Podcast #249 is available: http://soldersmoke.com/soldersmoke249.mp3
There is also a video version of this podcast: https://youtu.be/5xyaYivtOhw
Travelogue:
HAPPY VETERANS' DAY TO PETE AND GRAYSON AND TO ALL THE OTHER VETERANS WHO ARE LISTENING.
Trip out to San Francisco. Sticker placed on the corner of Haight and Ashbury: See picture below. Note other sticker. Really Groovy!
Stabilizing the EB63A (with Pete recommended LP filters from e-Bay.
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Cuban Cacharreo! Andy CO2AFV's Knack Story https://soldersmoke.blogspot.com/2023/10/a-cuban-knack-story-and-pandemic-sits.html
Bill's DXCC-100. DONE.
Tribal Wisdom: W1REX on HRWB https://soldersmoke.blogspot.com/2023/11/listen-to-rex-w1rex-lots-of-tribal.html
Pete's Bench:
Pete's 6BA6 rig
Pete's 6BA6 Rig
Pete Re-invents the Shirt-pocket SSB Rig
Pete's remake of the ShirtSleeve Transceiver
Pete Builds Two Computers
Pete Adds a Second Band to his Homebrew SDR
BEZOS BUCKS ARE BACK! PLEASE BUY THERE! >>>>>>>>>>>>>>>>>>>>>>>
Mostly DIY RF: Work proceeds in the Oregon Silicon Forest on P3ST kit development. Todd is confident the P3ST will be released on December 18th.Many other kits available now: https://mostlydiyrf.com/
Sign up for the newsletter: https://mostlydiyrf.com/subscribe/
Bill's Bench:
Rebuild of the 15-10 VFO (for improved Dial Spread) (with yet another QF-1 capacitor) https://soldersmoke.blogspot.com/2023/10/dial-scale-linearity-spreading-out.html
Why Building for 10 meters is harder: https://soldersmoke.blogspot.com/2023/09/why-building-for-10-meters-is-harder.html
Copper Tape shielding of 15-10 rig.
Crushing Spurs with Better Bandpass Filters (see blog post) https://soldersmoke.blogspot.com/2023/09/crushing-17-and-12-meter-spurs-with.html
Another 15-10 rig in the works... for SSSS. Boards are accumulating...
More problems discovered with the Herring Aid 5 Receiver . Lots of SS blog posts Comment from Rick WD5L. ) https://soldersmoke.blogspot.com/2023/10/a-big-error-discovered-in-1976-qst.html Did you try to build one? Did you succeed or did you fail? Please let us know.
The Basil Mahon books (blog posts) https://soldersmoke.blogspot.com/2023/11/basil-mahon-is-author-for-us-he.html
The Sunburst and Luminary book of Don Eyles (blog posts)
The Art of Electronics by Horowitz and Hill (blog posts)
Spectrum Analysers: Tiny SA Ultra https://soldersmoke.blogspot.com/2023/09/the-tinysa-ultra-spectrum-analyser-video.html and Polarad 632C-1; George WB5OYP gave me one of these spectrum analysers (I NEED a manual! Does anyone have a manual or a schematic? ) :
Polarad 632C-1
Stabilizing the EB63A (with Pete recommended LP filters from e-Bay.
MAILBAG:
TRANSISTOR MAN T-SHIRTS! Thanks to Roy WN3F!
Todd VE7BPO on AF amplifiers. Thanks Todd.
Wes W7ZOI -- Always a privilege to exchange e-mail with Wes.
E-mail from Jay Rusgrove W1VD. About the Herring Aid 5.
E-mail from Eamon Skelton EI9GQ! Amazing!
HB2HB with Denny VU2DGR https://soldersmoke.blogspot.com/2023/09/hb2hb-contact-with-denny-vu2dgr.html
Nick M0NTV on diode matching for ring mixers: https://soldersmoke.blogspot.com/2023/10/does-matching-matter-diode-matching-for.html
Paul Taylor VK3HN on the new Elecraft CW rig.
Dean KK4DAS fixed the noise in his Hallicrafters SW receiver. A long battle, finally won.
Dean also in contact with G3UUR.
Ramakrishnan VU2JXN helping me set up a backup of blog on WordPress.
Mark KA9OOI noticed that SS podcast archive appears gone. In fact just temporarily relocated to http://soldersmoke.com/
(SS PODCAST Archive temporarily relocated to http://soldersmoke.com/
Andreas DL1AJG - Crystal radio video. https://soldersmoke.blogspot.com/2023/10/building-crystal-set-videos.html
George N2APB on the Herring Aid 5
Grayson KJ7UM experimenting with Varactors and Thermatrons!
Thomas K4SWL on Mattia's DC receiver. https://soldersmoke.blogspot.com/2023/10/mattia-zamanas-amazing-direct.html
Bob Weaver of Dial Bandspread Linearity fame. Electron Bunker
Mike Bryce WB8VGE QRP Hall of famer -- he too couldn't get the Herring Aid 5 working.
Kirk NT0Z wrote about the Wayback machine. But this former ARRL staffer he also tried and failed to get the Herring Aid 5 going. Way back when... https://soldersmoke.blogspot.com/2015/03/kirks-herring-aid-tuna-tin-and-regen.html
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New 15-10 VFO with schematic
Dial Bandspread (Before)
At corner of Haight and Ashbury
Wednesday, November 1, 2023
Basil Mahon is an Author for Us -- He explains Faraday, Maxwell, and Heaviside
I bought his book on Maxwell so I can read it on a long flight our to California.
PERSONAL:
Born May 26, 1937, in Malta; married Ann Hardwick (a teacher of chemistry), April 1, 1961; children: Tim, Sara, Danny. Education: Attended Royal Military Academy, Sandhurst, 1955-57; Royal Military College of Science, B.Sc., 1960; Birkbeck College, London, M.Sc., 1971.
Check out his career:
British Army, career officer, serving with Royal Electrical and Mechanical Engineers in Germany, Aden, and United Kingdom, 1955-74, retiring as major; Government Statistical Office, civil servant, 1974-96. Consultant and trainer on censuses and statistics, including work for clients in Russia, Estonia, Croatia, and Republic of Georgia.
And his thoughts on writing:
Basil Mahon on writing: "To me, the joy of writing is simply the chance to give readers the joy of reading—to share one's thoughts and passions with them, hoping to leave them with a feeling of pleasure and well-being. By the time I came to write The Man Who Changed Everything: The Life of James Clerk Maxwell, careers in the army and the civil service had given me plenty of practice in writing instructions—where crispness and clarity were the cardinal virtues—so the big test was to try to hold fast to these qualities and to entertain the reader at the same time."
From the Netherlands, Manu Joseph explains why he loves Mahon and Forbes' book on Faraday and Maxwell:
Thank you Armand, and thank you Basil Mahon.
Saturday, October 14, 2023
Paul VK3HN's Video on Scratch-Building and SOTA
It was great to get a comment from Paul VK3HN -- this led to a re-establishment of contact. Apparently Google knows who I have been e-mailing, so this great video appeared on my YouTube screen. Thanks Google!
-- Great to hear Paul's shout out to Pete Juliano N6QW, and Pete's concept of noodling.
-- Paul's emphasis on testing each stage independently is really important.
-- Wow, ferric chloride! It is great to see someone doing this (instead of just sending Gerber files to China).
-- Books. This reminds me that I have to get Drew Diamond's books.
-- Paul's comment on the usefulness of a general coverage receiver. Right on target Paul.
-- On the test gear, we can now add the TinySA Ultra. And you don't have to win the Lotto!
-- Finally, Paul is absolutely right on the need to constantly update and publish changes to schematics. I am guilty of not doing this. (I hang my head in shame.) This became a problem in our simple High-School receiver project -- I would make changes to circuits and fail to communicate these changes to Dean KK4DAS. Paul's method would have solved this problem.
-- Thanks Paul!
Saturday, September 23, 2023
Sunburst and Luminary -- An Apollo Memoir by Don Eyles (video)
Buy the book from the Amazon link on the right side of the page >>>>>>>>>>>>>>>>>>>>>>>
There is so much great stuff in this 2018 video. I am definitely going to buy the book. This is another of those things that reminds me (a hardware guy) of the importance of software (Sunburst and Luimary were the names of two programs that Eyles wrote to enable the LEM to land on the moon).
-- Asked about one of the biggest ancillary contributions of the Apollo program, Eyles immediately says, "integrated circuits." They used three terminal NOR gates. Lots of them.
-- They never had a hardware failure in the Apollo computers. Demonstrating a classic troubleshooting technique, when they discovered what they thought was a hardware failure, they ran the program on another computer. The problem was also there, so they knew there had been no failure on the first machine.
-- The LEM simulator was very cool.
-- Eyles' ability -- in two hours -- to write the code for the automatic landing program that Astronaut John Young was asking for, then have it flown on an Apollo mission to the moon was very impressive.
Thanks to the MIT Museum for posting Don's talk. And thanks to HackADay for alerting us to it.
Also, take a look at this one: https://www.youtube.com/watch?v=oi4h04ZgQsQ
Saturday, September 16, 2023
"The Art of Electronics" by Horowitz and Hill (First in a Series of Blog Posts on this Great Book)
Paul Horowitz
Oh man, this book is so good. You really just need to buy it now. I put it in the Amazon link to the right.
OVER HERE >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
The Imsai guy reminded me of this book, and pointed out that earlier editions are more reasonably priced, so I got the second edition (looks like 1980, reprinted many times through 1988). Dean KK4DAS got one too (I think he also got the second edition).
Lest there be any doubt that this book is for us, first let me point to the pictures of Paul Horowitz and Winfield Hill. https://artofelectronics.net/about/
Winfield Hill
Just from the pictures, you can tell that these guys have THE KNACK. And -- get this -- THEY ARE BOTH PROFESSORS AT HARVARD. Wow.
Their web page explains where the book came from:
Dean KK4DAS and I have already started sharing quotes from the book:
Referring to other books, H and H write: "Much of the favorite pedagogy of beginning textbooks is quite unnecessary, and, in fact, is not used by practicing engineers, while useful circuitry and analysis lies hidden in application notes, engineering journals, and hard-to-get data books."
"Thus, the treatment of this book reflect our philosophy that electronics, as currently practiced, is basically a simple art, a combination of some basic laws, rules of thumb, and a large bag of tricks. For these reasons we have omitted entirely the usual discussion of solid state physics, the h-parameter model of transistors, and complicated network theory, and reduced to the bare minimum the mention of load lines and the s-plane. The treatment is largely non-mathematical, with strong encouragement of circuit brainstorming, with mental (or, at most, back-of-the-envelope) calculation of circuit values and performance."
Stay tuned. There is a lot more coming about this wonderful book.
Sunday, April 16, 2023
Inside "Open Circuits"
Here is a cool video about a very cool book. I wasn't going to buy it, but when I saw it in a book store, I opened it up to a random page and found myself looking at the 2N3904. TRGHS. So I bought it.
Monday, March 20, 2023
Winterfest Loot: Who Can ID the Homebrew Receiver?
First a big congratulations to the Vienna Wireless Society and its President, Dean KK4DAS. In spite of low temperatures that made the Winterfest Hamfest live up to its name, this year's 'fest was a big success with excellent turnout both by buyers and sellers. There were a LOT of older rigs -- on one table I saw three HT-37s. It was all great. Here is a video of the hamfest. https://www.youtube.com/watch?v=oheht5jCuKE&t=619s This was shot early on Sunday morning March 19, 2023, about 30 minutes after it opened. An hour later there were a lot more customers.
One of the first things I bought was the item pictured above. I bought it mostly because we are currently building 40 meter receivers with the local high-school students. I didn't have a screw driver, so I couldn't open up the box. Something was rattling around in there. I worried that the box might be mostly empty. Or that it would have one PC board with a sad collection of ICs. But in the hope that I would find something truly homebrew, I bought it.
Below are pictures of what I found inside. Can anyone tell us what this is? ( I recognized it immediately.) More on this device in due course.
Other loot from the 'fest:
The one on the left I've been using since around 1998! It is getting beat up. I bought the one on the right at the 'fest. It is in much better condition. 5 bucks. TRGHS.
I always wanted one. I had nice leather case, but I gave it to Dick Dillman years ago. I now feel like a real boatanchor guy. I got for 15 bucks. I see on Amazon they are selling for $466!
I had one as a kid. Will be useful in the DR. In great shape.
Eamon Skelton's book was a great find. As were the early editions of SSB for the Radio Amateur. Eight bucks for the whole lot.
I like homebrew speaker enclosures. They add soul to the new machine. Perhaps a prize for the high-school project. Three bucks.
Finally, this thing. Plagued by guilt for past cannibalizations of QF-1s, I was going to pass on this one, but I realized that my friend Dean KK4DAS would be on his way, and if I didn't take it (and extract the variable capacitor) he would. So I bought it. But I may leave this one as is, for possible use as the The Radio Gods intended. It could use some cleaning up. It seems to have a coat of nicotine. Ten bucks.
I also picked up a few larger knobs that may be of use with the high-school receivers.
Friday, January 20, 2023
Open Circuits: The Inner Beauty of Electronic Components
I was not going to buy this book. But then, Elisa and I were in a book store and there it was. I decided to take a look. I opened it to a random page: 2N3904. TRGHS. Sold.
It is really interesting.
You can order yours through the Amazon Search block in the right side column of the blog.
Wednesday, December 7, 2022
Is Envelope Detection a Fable? Or is it Real? Diodes, Square Laws and all that
HOW ENVELOPE DETECTION (SUPPOSEDLY?) WORKS
Most of us grew up with the above diagram of how a receiver detects (demodulates) an AM signal. Here is how they say it works:
-- Because of the way the sidebands and the carrier in the transmitted signal interact, we end up with a signal whose "envelope" matches the frequency of modulation. And we just need one side of the envelope.
-- We used a simple diode to rectify the incoming signal.
-- A simple filter gets rid of the RF.
-- We pass the resulting signal through a capacitor and we get audio, which we listen to.
REASONS FOR SCEPTICISM
But recently, a member of my local radio club has questioned this explanation of AM detection. He maintained that "envelope detection" is not real, and that was actually happening was "square law" mixing. I guess there are reasons for skepticism about the envelope detection explanation: The envelope detection explanation does seem very (perhaps overly) simple. This does sound a bit like the kind of "dumbed down" explanation that is sometimes used to explain complex topics (like mixing). Envelope detection does seem consistent with the incorrect insistence from early AMers that "sidebands don't exist." (Of course, they do exist.) All the other detectors we use are really just mixers. We mix a local oscillator the incoming signal to produce audio. Envelope detection (as described in the diagram above) seems oddly different.
Denial of envelope detection can even be found in the ARRL handbook: On page 15.9 of the 2002 edition we find this: "That a diode demodulates an AM signal by allowing its carrier to multiply with its sidebands may jar those long accustomed to seeing diode detection ascribed merely to 'rectification.' But a diode is certainly non-linear. It passes current only in one direction and its output is (within limits) proportional to the square of its input voltage. These non-linearities allow it to multiply."
ISN'T THIS REALLY JUST MIXING, WITH THE CARRIER AS THE LO?
It is, I think, tempting to say -- as the ARRL and my fellow club member do -- that what really happens is that the AM signal's carrier becomes the substitute for the VFO signal in other mixers. Using the non-linearity of the square law portion of the diode's characteristic curve, the sidebands mix with the carrier and -- voila! -- get audio. In this view there is no need for the rectification-based explanation provided above.
But I don't think this "diode as a mixer, not a rectifier" explanation works:
In all of the mixers we work with, the LO (or VFO or PTO) does one of two things:
-- In non-switching mixers it moves the amplifier up and down along the non-linear characteristic curve of the device. This means the operating point of the device is changing as the LO moves through its cycle. A much weaker RF signal then moves through the device, facing a shifting operating point whose shift is set by the LO. This produces the complex repeating periodic wave that contains the sum and difference frequencies.
-- In a switching mixer, the device that passes the RF is turned on and off. This is extreme non-linearity. But here is the key: The device is being turned on and off AT THE FREQUENCY OF THE LO. The LO is turning it on and off. The RF is being chopped up at the rate of the LO. This is what produces the complex repeating wave that contains the sum and difference frequencies.
Neither of these things happen in the diode we are discussing. If you try to look at the diode as a non-switching mixer, well, the operating point would be set not by the carrier serving as the LO but by the envelope consisting of the carrier and the sidebands. And if you try to look at is as a switching mixer you see that the switching is being controlled not by the LO but by the envelope formed by the carrier and the sidebands.
Also, this "diode as a mixer" explanation would require the diode to be non-linear. That is the key requirement for mixing. I suppose you could make a good case for the non-linearity of solid state diodes, but the old vacuum tube diodes were quite linear. The rectifying diode mixer model goes back to vacuum tube days. The "diode as rectifier" model worked then. With tubes operating on the linear portion of the curve, the diodes were not -- could not -- have been working as mixers. We have just substituted solid state diodes for the tubes. The increased non-linearity of the solid state diodes does introduce more distortion, but the "detection by rectification" explanation remains valid.
Even in the "square law" region (see diagram below) an AM signal would not really be mixed in the same way as signals are mixed in a product detector. Even in the square law region, the diode would be responding to the envelope. Indeed, the Amateur Radio Encyclopedia defines "Square Law Detector" as "a form of envelope detector." And even in the square law region, the incoming signal would be rectified. It would be moving above and below zero, and only one side of this waveform would be making it through the diode. Indeed the crystal radio experts discuss "rectification in the square law region" (http://www.crystal-radio.eu/endiodes.htm ) So even in the square law region, this diode is a rectifying envelope detector.
THE BEST PROOF
Here is what I think is the best proof that the "envelope detection" explanation is real: In this video, we see someone build an envelope detector in a simulator. Watch as he then traces the signals as they move through the diode, the RC filter, and the coupling capacitor. He goes through it cycle-by-cycle. You can clearly see how the rectification of the AM leads to envelope detection.
The rectifying envelope detection model goes way back in radio history, back to when authors did not shy away from complex technical explanations. Terman knew how mixers worked, and his 1943 "Radio Engineers Handbook" went to 1019 pages. Terman presented it as a rectification-based detection of the envelope. I think envelope detection is real, and that Dr. Terman was right.
--------------------------------------
Some links that might help:
Analog Devices has a very good, rigorous site showing how envelope detectors work:
Here is great article by W4ENE on Envelope Detectors and how they have been used in ham receivers over the years:
This QEX article begins with some useful vector diagrams showing how the sidebands and carrier combine to form an envelope that is equal to the frequency of mondulation: https://swling.com/blog/wp-content/uploads/2009/08/syncdetectionarrl.pdf
RF Cafe has some good graphs showing the linear and "square law" portions of the crystal diode's curve (see above): http://www.rfcafe.com/references/electrical/ew-radar-handbook/detectors.htm
The crystal radio guys have a good take on square law detection (note, they just see it as rectification, but on a lower, more parabolic portion of the curve): http://www.crystal-radio.eu/endiodes.htm
Here is a good booklet from 1955 on AM Detectors: https://worldradiohistory.com/BOOKSHELF-ARH/Rider-Books/A-M%20Detectors%20-%20Alexander%20Schure.pdf
Monday, September 26, 2022
Open Circuits: Cutting Open Components for a Look inside -- First Chapter Free
Bob KD4EBM sent me this:
“…. Eric Schlaepfer (@TubeTimeUS) and Windell Oskay (co-founder of Evil Mad Scientist)’s latest book, Open Circuits, is a celebration of the electronic aesthetic, by literally opening circuits with mechanical cross-sections, accompanied by pithy explanations and illustrations. Their masterfully executed cross-sectioning process and meticulous photography blur the line between engineering and art, reminding us that any engineering task executed with soul and care results in something that can inspire feelings of awe (“wow!”) and reflection (“huh.”): that is art. …”
I saw on Hack-A-Day today that the first chapter of the book is available as a free download:
https://nostarch.com/download/OpenCircuits_Chapter1.pdf
Many of our favorite parts are dissected in that chapter. The innards of a ceramic disc capacitor, for example, are shown above.
Thanks Bob!
Thursday, September 8, 2022
Another Free Book: Contra Cross
The free Kindle offer is now on!
Bezos is letting me give this one away for five days: September 9, 2022 12 am PDT to September 13 2022 11:59 PDT. So go ahead and put it in your Kindle. It is not about radio, but I think many SolderSmoke fans will like it.
Download it here:
Please spread the word and -- if you like -- write a review.
Sunday, September 4, 2022
Free Book! "SolderSmoke -- Global Adventures in Wireless Electronics" by Bill Meara. Free for the Next Five Days
From time to time, Amazon lets me make my books available for free on Amazon Kindle. SolderSmoke -- Global Adventures in Wireless Electronics is now -- and for the next five days -- available for free download. Use this link:
https://www.amazon.com/gp/product/B004V9FIVW/ref=dbs_a_def_rwt_hsch_vapi_tkin_p1_i1
Please spread the word and post reviews. Comments posted on the Amazon page (above) are especially welcome.
Sunday, July 10, 2022
A Truly Great Book: "From Atoms to Amperes" by F.A. Wilson (Free Download)
This is a really wonderful book. I'm glad worldradiohistory.com has found a way to make it available as a free download. This is the kind of book that you want to download and keep available for future study. The day will come, for example, when you will want to understand how Einstein's special relativity explains how that transformer in your rig actually works. F.A. Wilson explains that, and much more. Here is the link:
https://worldradiohistory.com/UK/Bernards-And-Babani/Bernards/BP254-From-Atoms-To-Amperes-Wilson-1989.pdfoke.com
Thanks to Joefish for the heads-up.
Sunday, June 19, 2022
A Great Book on Oscillators (Analog LC Oscillators) by John F. Rider (Free!)
Thanks to Peter Parker VK3YE for alerting us to this wonderful 1940 book. John F. Rider -- a real hero of electronic literature -- does a great job in discussing the practical aspects of oscillator circuits.
This excerpt from Rider's foreword gives a sense of the approach taken in this book:
The book covers a lot of material. In addition to the standard oscillator circuits, he discussed multivibrators, relaxation oscillators and much more. There is a chapter on magnetostriction in which he shows that this property is the basis for crystal oscillators AND the mechanical filters that we are familiar with. In fact he seems to take what we would consider a mechanical filter and put it in the grid circuit of a tube to make an oscillator.
He discussed the modulation of oscillators. He describes the Heising modulator that caused young Jean Shepherd so much teenage heartache.
Download the book here:
Wednesday, June 8, 2022
SolderSmoke FDIM Interview: Jack Purdum W8TEE on the Challenges of Decoding CW by Software
In his interview with SolderSmoke correspondent Bob Crane, Jack Purdum made some very interesting comments about the challenges of decoding CW with software. He notes that W1AW's code practice CW is perfect, but that below 18 wpm, they deliberately insert a "Farnsworth Delay" that increases the spacing between words -- this complicates automatic CW decoding.
Jack also talked about the distinctiveness of different CW operators. Jack noted that W1AW has no real "fist" in this sense: "It has the personality of a stick!"
Jack mentioned that Pete Juliano had been reading book on SDR radios that Jack and Al Peter recently published: https://www.amazon.com/Software-Defined-Radio-Transceiver-Construction/dp/B09WYP1ST8/ref=sr_1_1?crid=2KPYAMPOW5P6J&keywords=DR.+Jack+Purdum&qid=1654598559&sprefix=dr.+jack+purdum%2Caps%2C40&sr=8-1
Here is our correspondent Bob Crane's interview at FDIM 2022 with Jack Purdum: http://soldersmoke.com/2022 W8TEE.mp3
Thanks Bob. Thanks Jack.
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