Test Gear/Workbench Maintenance

I mentioned in the last podcast that I was going to take a break from construction projects and spend a little time fixing up tools, test gear, and the work bench. First up was my old soldering gun. I bought this thing almost 40 years ago! It is pretty beat up, but I managed to patch it up and it now works fine. Even the original light bulb works.

I use this little AADE L/C meter a lot, but was having trouble getting parts across the test terminals. So I soldered alligator clips onto one of the parts connectors that came with the device. Makes testing easier.

Just a little audio oscillator. Puts out .2 volts at 713 Hz. Useful for testing the phone rigs.

I picked up this little Lafayette power supply at a hamfest and found it quite useful. But then I managed to knock the needle off the meter while fooling around with trivial electric motor. Any ideas on where I could get a replacement meter movement, or on what value I should use?

Here is a wave meter that I picked up at the Kemptom Park rally in London. Apparently at one point all UK radio amateurs were required to have one of these devices. I'm tempted to chop it up for parts. That variable cap with the reduction drive looks promising. And could that meter solve my problem with the power supply (above). If anyone can think of a reason to keep this as a wavemeter, please let me know.

Further proof of my extreme retro-ness. This is what I use as a signal generator. A Heathkit SG-6. Older than me!

This is my scope. HAMEG. Supposed to be good to 10 MHz but of course I can use it at higher freqs (which I do). I need to upgrade. Any suggestions?

A very useful little square wave generator.

I need to make more use of this noise bridge. Lots of potential here.

Obviously a London purchase. Very useful little AF sig generator from the UK's equivalent of Radio Shack. My only complaint: No auto-off. I forget to turn it off and run down the two 9 V batteries.

Long time listeners will remember this device. This is the one in which I soldered in the chip upside down. It works fine on th 5 Hz to 100 MHz range. Dead on the 4 - 600 MHz position.

I bought this power supply at the Kempton Rally, then converted it into a current limited supply using a chip and a circuit provided by Tony, G4WIF. My daughter Maria helped paint the cabinet. Lots of soul in this little machine.

Just three meters. The middle (analog one) is still very useful, and has considerable sentimental value for me -- my wife got if for me when we were back in the Dominican Republic.
My version of the W7ZOI power meter. Mike, KL7R, and I built versions of this device back in 2004 or so.
This is Cappuccio. He joins me in the shack most mornings. I'm not really a dog person, but I'm growing fond of him, even though he occasionally eats resistors and capacitors.

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Homebrew Ferrari

Speaking of homebrew motors, a number of people sent me this YouTube video about another intrepid European with amazing workshop skills. Great stuff. (It reminded me of the title of one of Jean Shepherd's books: "Ferrari in the Bedroom.")

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The Woz's Early Exposure to Electronics

Here is what I was trying to --- hic-- say about Steve Wozniak --hic-- in Podcast #139:

From "Steve Jobs" by Walter Isaacson:

"One of Steve Wozniak's first memories was going to his father's workplace on a weekend and being shown electronic parts, with his dad "putting them on a table with me so that I could play with them." He watched with fascination as his father tried to get a waveform line on a video screen to stay flat so that so that he could show that one of his circuit designs was working properly. "I could see that whatever my dad was doing, it was important and good." Woz, as he was known even then, would ask about the resistors and transistors lying around the house, and his father would pull out a blackboard to explain what they did. "He would explain what a resistor was doing all the way back to atoms and electrons. He explained how resistors worked when I was in the second grade, not by equations, but by having me picture it."

This is clearly the approach to electronics that we see in the book "From Atoms to Amperes" by F.A. Wilson.

Mike, KC7IT, gave Woz a new title "the uber-knack-master of all time":

Woz is the uber-knack-master of all time, and always has been in my book. His Apple II design is a work of genius in getting ten pounds of function out of five pounds of parts.

One of many examples: Apple II was the first personal computer to use DRAM memory chips, which were brand new then and kinda scary even for us pros. DRAMs store data as charges on tiny leaky capacitors. Every 20 milliseconds or so they have to be refreshed.

Everyone else had counters and logic just for refresh. Woz arranged the Apple II's display memory, so reading out the pixels to the TV screen 60 times per second did the refresh too, at no cost in circuits or performance. The elegant design of a pure knack genius.

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Hiccups in SolderSmoke 139

First there was the whistling of my SSS sounds (a speech defect that I had been blissfully unaware of due to a nullifying case of tinnitus!) Then, in SolderSmoke 139 the long-suffering SolderSmoke listeners had to put up with hiccups. Yea, around 53 minutes into the show there began an annoying series of hiccups. Being an essentially analog kind of guy, I'm sort of pleased to point out that these are DIGITAL hiccups, apparently introduced by the Audacity software during the actual recording (not when I converted the show to mp3). I've been having more than my normal share of road-kill computer problems lately. The laptop I'm using to record the show ate a couple of the recent episodes before I had a chance to upload them (I had to do them over -- that's very frustrating). So this time I was recording the show on a thumb drive. Apparently it was filling up as we got close to the end, which led to the hiccups. The worst part was that a hiccup came just as I was delivering a key quote from The Woz. (I'll post it.)

If anyone has any gear laying around that might with these problems, please send it my way. Obviously I could use a bigger thumb drive. An external sound card might be nice. I could probably use another laptop also...

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30% off on SolderSmoke, The Book. December 7

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Messaging ET (METI), and Silicon-based Life Forms

My fellow beacon fans will like this one. The ultimate (REALLY ultimate) beacon! http://www.newscientist.com/article/dn21236-lets-build-a-beacon-to-tell-aliens-who-we-were.html?page=1

And then there is this article about silicon-based life forms. (At first I thought they were talking about us!) http://www.universetoday.com/91449/why-silicon-based-aliens-would-rather-eat-our-cities-than-us-thoughts-on-non-carbon-astrobiology/

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SolderSmoke Podcast #139

December 3, 2011

http://soldersmoke.com/soldersmoke139.mp3

Halloween, Thanksgiving, and Billy's Birthday (on the range!)

Astro-Knack: CCD camera in the telescope. Solar astronomy.

Winter approaches: Shack heating by Heath, Halli, Hammarlund and Drake.

2B troubles on 17 meters.

Rig Re-Cycling: Rebuilding 17 meter rigs from the last solar cycle.

Azores DSB re-build: Oscillator troubles then adding a JBOT.

Manhattan style construction and the need for urban renewal.

Book Review: Steve Jobs. (Woz has the Knack!)

MAILBAG

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An Inspirational Homebrew Motor from Spain

Bruce, KK0S, alerted me to this inspirational masterpiece from Spain. It is, as he points out, one of a number of really great videos about top level homebrew craftsmanship from Europe (remember the French homebrew tubes?).

Other comments from Bruce:
Did you notice that the calipers and micrometer this guy was using were seriously old-school. Totally manual readout. Not even a dial on that set of calipers! On top of that, his little lathe was manually fed. Notice in one of the shots, he is shown turning the cross slide feed wheel. No CNC anywhere. I can't be positive, but I don't think the lathe had a digital position readout either. This man is a machinist in the truest sense of the word. The Knack not only lives - it thrives!

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Secret Listeners -- The Voluntary Interceptors

Jim, AL7RV, and several others sent me the link to this really interesting video about the British radio amateurs in WWII. Real "stiff upper lip" spirit in this video. Musn't grumble! Great stuff from Great Britain: http://www.eafa.org.uk/catalogue/5108

That regen receiver they showed looks a lot like the beast that I brought back from the UK with me. Once again, I am hearing the siren song of the diabolical regens....

Progress continues on my Indian-ized Azorean DSB transceiver (with JBOT amp). I now have the amp nicely stabilized (thank God!). Now I just need to get the output from the balanced mod close to the 1 mW PEP level needed by the amp. Should be done soon. And my cold seems to be going away, so maybe I'll be able to share my tales of JBOT derring-do in a podcast this weekend.

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30% off on SolderSmoke, The Book. Cyber-Monday Sale. November 28

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A Re-balanced Modulator for my Re-cycled Rig

My effort to bring my Azorean 17 meter DSB rig back to life continues. This is proving to be harder than I thought. I'm still taming my version the JBOT amp. It still seems to break into oscillation -- I think the oscillation freq is around 1 MHz. But I am making progress.

I had to go back and work on the balance modulator circuit. I really like the simple two diode singly balanced mixer circuit. But my original Azorean board had, like the oscillator board, been through a few too many rounds of modification and repair. I decided to start over. See above. I even came up with my own little innovation on this circuit. Doug DeMaw's original design called for a 100 ohm pot at the junction of the two diodes, with the signal coming off the tap. You adjust the pot to balance the circuit and null out the carrier. But I didn't have a 100 ohm pot. Lots of 1K controls were available, so I put in two 50 ohm resistors in place of the pot, then put the 1k pot between the diodes, with the tap to ground. This balances things out nicely. See below.

I hope to get a podcast out next week, but I've been suffering from a nasty headcold that would have introduced all kinds of weird audio effects.

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The Bar of King Arduino

I'm not sure what I would do with an Arduino, but articles like this definitely make me want one! Here's one passage:

To make the board, the group had a specific, student-friendly price as their goal: $30. "It had to be the equivalent of going out to dinner at a pizza place," Banzi says. They also wanted to make it quirky, something that would stand out and be cool-looking to erudite geeks. If other boards were often green, they’d make theirs blue; while some manufacturers economized on input and output pins, they’d add plenty to their board. As a final touch, they added a little map of Italy on the back of the board. "A lot of the design choices are weird for a real engineer," Banzi says with a knowing laugh, "but I’m not a real engineer, so I did it in a silly way!"

Here's the article. Note the origin of the name of the device.

http://spectrum.ieee.org/geek-life/hands-on/the-making-of-arduino/0

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Steve Smith (on the left) and Bill (with the filter)

Steve "Snort Rosin" Smith has been keeping me on the side of the angels (and the FCC regs) in the area of harmonic filtering. Today he sent me this Steve and Bill cartoon. Thanks Steve. Just what I needed as I prepare for my next attempt to get my JBOT (with filter!) to behave. Wish me luck!

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Amplifier Woes -- Help me! Help me!

When I look in the mirror and I see a haunted, obsessed look in my eyes. My wife senses that there is something wrong in the ham shack. She is right. I have an amplifier that wants to be an oscillator. Help me exorcise these gremlins! Guys, this problem is holding up the production of the next SolderSmoke podcast.

My JBOT amp works fine into a dummy load, but when I connect it to an antenna, it gets unstable. Here are some more details of the symptoms:

I am running the JBOT with a 5 element (two toroids, 3 caps) low pass filter (designed by Doug DeMaw and approved by Steve Smith).

With the antenna connected, all is well UNTIL I raise the power out (by varying the input) beyond about 1 watt. Below one watt, the amp is working fine, and it stable. As soon as I hit the 1 watt point, the amplifier seems to break into oscillation. This does not happen into the dummy load.

The antenna is a simple dipole fed by coax. It shows a low SWR. Even when I put an antenna tuner between the amp and the antenna and bring the SWR down to negligible levels, the instability problem persists.

With the amp disconnected from all other circuitry other than the antenna and the power supply, if I just touch the input capacitor, it breaks into oscillation. This does not happen when the amp is working into the dummy load.

I've bolstered the power supply filtering and decoupling. No luck. I tried some de-Qing of the transformers. No luck.

Any suggestions?

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Backyard Solar Astronomy

Over the weekend I took a break from JBOT amplifiers and did something I've been meaning to do for a long time: solar astronomy. I pulled out my old 4.5 inch Tasco reflector telescope and aimed it at old sol. I know, I know, this can be dangerous, but we were careful -- note that Billy is standing on the other side of the business end of the telescope. In his hands is the paper onto which we projected the solar image. I'd always wondered how I would get the sun into the telescope's field of view without risking my eyesight by using the finder scope. This turned out to be no trouble at all: I just looked at the shadow cast by the tube of the telescope and --using the shadow as my guide -- moved the tube until it was lined up with the sun. We snapped a picture of our results. I think our crude effort compared very favorably with the picture from NASA's Solar Dynamics Observatory. You can see the same sunspots in each image (ours is reversed because we were using a reflector). These images are from 12 November 2011.

Our picture

NASA's picture

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"The Knack" on a Mysterious Island

Paul, W2IOG, sent a nice e-mail about a very early use of the term "The Knack": 1874 by Jules Verne. (What word did he use in French?). I took a look at the Wikipedia page and discovered that there was indeed quite a bit of "The Knack" on Lincoln Island:

"With the knowledge of the brilliant engineer Smith, the five are able to sustain themselves on the island, producing fire, pottery, bricks, nitroglycerin, iron, a simple electric telegraph, a home on a stony cliffside called "Granite House", and even a seaworthy ship. They also manage to figure out their geographical location."

Hello Bill,

I have been a listener to your Soldersmoke pod-casts for a couple of years now. I am also a regular reader of the blog as well as a long time victim of "The Knack". I was browsing an old book store the other day when I came across a beautifully illustrated copy of Jules Verne's book "The Mysterious Island" copyright 1920. I couldn't resist, and when I reached chapter nine of part one of the book I was really glad I had made the purchase. In the story, which takes place in 1853, castaways on an apparently uninhabited island are trying to make fire for the first time. After trying and failing to make sparks by striking stones together, two of the castaways try the following:

"Pencroft, although he had no confidence in the proceeding, then tried rubbing two pieces of dry wood together, as [primitive people] do. Certainly, the movements which he and Neb gave themselves, if they had been transformed into heat, according to the new theory, would have been enough to heat the boiler of a steamer! It came to nothing. The bits of wood became hot, to be sure, but much less so than the operators themselves.

After working an hour, Pencroft, who was in a complete state of perspiration, threw down the pieces of wood in disgust. 'I can never be made to believe that [primitive people] light their fires in this way, let them say what they will,' he exclaimed. 'I could sooner light my arms by rubbing them against each other!'

The sailor was wrong to despise the proceeding. [Primitive people] often kindle wood by means of rapid rubbing. But every sort of wood does not answer for the purpose, and besides, there is 'the knack,' following the usual expression, and it is probable that Pencroft had not 'the knack.' "

Congratulations on getting that 17 meter rig back on the air!

Paul W2IOG


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Sunspots! QRP DSB contacts on 17 meters

You can see here why I had so much fun in the summer of 2001 with my Azorean Homebrew QRP DSB rig. And why I am now re-CYCLING (get it?) and refurbishing the 17 meter gear that I built last cycle.

I've had the DSB rig on the air yesterday and have worked seven stations (2 watts peak DSB to a dipole).

Back to the Future! Someone on QRP-L said the SFI was recently at 180! Go Sol!

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JBOT Amplifier Installed in Azorean DSB Rig

I've been remiss in posting to the blog, but I have a good excuse: I've been melting solder. I have working on the installation of my new Farhan-designed JBOT amplifier in my old Azorean DSB transceiver. I'm really enjoying this project, and I now see it as the first in a series. My shack has a number of creations that were built during the peak years of the last solar cycle, but have since fallen into disuse. Many of them were partially cannibalized -- usually it was the RF amplifier that was taken out. The JBOT was just what I needed. I plan to refurbish all of these rigs, adding a bit of India to each one of them. This is very much in keeping with our "International Brotherhood of Electronic Wizards" ethos.

The installation went fairly well, but with all of the ups and downs that accompany this kind of project. The amp worked fine on the bench, fed with a signal generator and into a dummy load. But of course, life got more complicated when I installed it in the rig. Yes, it took off on me. This was no fault of the amplifier -- I just needed to add some additional shielding. It is working fine now. See above. I moved it out of center stage and put it off in the corner to avoid feedback problems. More discussion of this in the next podcast (maybe this weekend).

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Tony Sale and the Re-Building of Colossus

Steve "Snort Rosin" Smith sent us this, noting that "Tony Sale definitely had The Knack." As the Brits would say, "indeed."

http://mathdl.maa.org/mathDL/?pa=mathNews&sa=view&newsId=1195

Amazing info on Tony Sale's work here:
http://www.codesandciphers.org.uk/lorenz/index.htm

I got a kick out of this bit:

One reason for wanting to get Colossus working in 1996 was that for far too long the Americans have got away with the myth that the ENIAC was the first large-scale electronic digital calculator in the world. It was not, but they got away with it because Colossus was kept secret until the 1970s. As 1996 was the 50th anniversary o the switch-on of ENIAC I made sure that Colossus was rebuilt and working in Bletchley Park, just as it was in 1944.

There has been a stunned silence from across the water!

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21st Century Ham Radio -- EDN Article

A few listeners sent this in. Thanks! Note the mention of AA1TJ's CFL light bulb rig!

http://www.edn.com/article/519742-Ham_radio_in_the_21st_century.php


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First Flight in Electric Multi-copter

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Recreational Engineering

I like that term! "Amateur Engineering" always seemed to sound kind of scary, conjuring up images of bridges that don't quite stay in place. "Recreational Engineering" has a nicer, less ominous ring to it. I found this phrase at the end of this newspaper article on the Maker movement:

http://www.csmonitor.com/Innovation/Tech/2011/1101/Maker-Faire-Mad-science-for-the-masses/%28page%29/2


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Happy Birthday Arecibo! A Tour of the Radio Telescope

Yesterday I was listening (as I do each morning at 0635) to Garrison Keillor's "Writer's Almanac." (I use a beautiful old FM broadcast receiver that Rogier out in California sent me for my birthday.) Garrison announced that it was the birthday of the Arecibo radio telescope (it opened on November 1, 1963). I wanted to post something about this on the blog, but was running a bit late and didn't get to it. This morning I was greeted by an e-mail from Ken, KG6PO, alerting me to a really magnificent video tour of the Arecibo facility. Wow. This is truly amazing. You guys are going to love this one. Three cheers for Bob Zimmerman! As I watched, I got the distinct feeling that we were visiting Bob's shack, and that the dish was his antenna!

Please spread the word about this video -- it is a real shame that it has only received 757 views. Three cheers for the guys who filmed this. Beautiful work.

Links:

http://youtu.be/kQJawfbjpxw

http://www.youtube.com/watch?v=kQJawfbjpxw

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Pumpkin Pi and JBOT Gremlins

Maria wanted to go with a mathematical theme for this year's Jack-0-Lantern. Pumpkin Pi!

I have been chasing some gremlins and banshees around my old Azores 17 meter DSB rig. The JBOT Amp worked fine into a dummy load, but of course things got a bit more complicated when I put it into the rig and connected it to an antenna. It would take off (like a banshee!) if the load was at all reactive. I think this is the result of inadequate shielding and inputs a bit too close to outputs. But it all settles down nicely when I put a transmatch in the antenna line and tune out the reactance. I may just leave it this way.

Output is a bit low -- only about 1 Watt. I realize that at 18 MHz output should be dropping a bit, but I think I should be getting more. I THINK I'm giving it the recommended 1 milliwatt input. At some point I think Farhan mentioned the possible need to experiment with the number of turns on the secondary of the output transformer....

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Snow Static

Related to our post about my new (old!) all-boatanchors heating system (see below), yesterday I had some really horrendous static. I think it was caused by the snow. A Google search on "snow static" brought me to this video (which Gregg in Finland found "shocking""). I liked the tuner and the neon bulbs too.

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My New Shack Heating System: Heath, Halli, Hammarlund and Drake

Temperatures dropped over the weekend and I had to fire up my new heating system for the SolderSmoke shack. See above. Heating by Heath, Halli, Hammarlund and Drake (sounds like a law firm doesn't it?). I'm happy to report that those old filaments take the chill off quite nicely while adding a nice aroma to the room, along with some very pleasing lighting effects (I especially like the green glow from the DX-100 tuning dial).

The Azores-17 DSB JBOT project is (I think) complete. And I did include a low pass filter. In keeping with the finest of ham radio traditions, now that it is cold I will go out and work on an antenna.

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Another Treasure Trove: The Royal Society's Archive

I'm a big fan (wanna-be really) of The Royal Society. In SolderSmoke 138 I noted that Isaac Newton (former Society president) seems to have had The Knack. And when I was in London one of the major perks of my job was that I occasionally got to visit the Society's headquarters. Bill Bryson recently edited a book about the Royal Society -- in his intro he noted that they have always been a very international group (just like us!)
Several readers wrote in with the happy news that the Society's 350 year archive has been placed on-line. Here it is:
http://royalsocietypublishing.org/site/authors/free-archive.xhtml

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Homebrew Jet Engine from Junkbox Parts!

Bob, W8SX (our man in Dayton) sent me this nice video. I really liked the friendly and enthusiastic way in which the builder described his project. I only wish he would have fired it up! Thanks Bob!

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Azorean Oscillator Re-build

With my JBOT amp ready for installation, it was time to go back and check out the rest of the circuitry on my old Azorean DSB/Direct Conversion 17 meter "Magic Carpet" transceiver. I was surprised to find that the oscillator, well, wouldn't oscillate. The MPF102 that I had in the main oscillator circuit was blown. I suspect voltage spikes from the T/R relay. I installed the required diode across the relay coil. (I seem to blow up a lot of MPF102s. Is it just me, or are these devices really fragile? They are junction FETs, not MOSFETS, so I thought of them as being more robust. But I seem to go through a lot of them.)

After messing around with the oscillator and buffer circuits, the nice clean Manhattan isolation pads that had been there at the start were all messed up, with big piles of solder with the ends of multiple axial leads stuck in there. I decided to start afresh. Out came the little PCB box that housed that housed the oscillator, buffer and amp stages. Off came the walls of the box. (When I built this thing the first time, I didn't realize that I would need an amp to get to the 7 dbm needed to drive the diode ring. I ran out of room on the main board and ended up building the needed amplifier on the back wall of the box!)

So I got to build this little circuit again, ten years and three countries after the original build. It was fun. I like building oscillators. There is that satisfying sense of closure and completion when, at the end of the effort, you turn on your receiver and hear the tone from your creation.

There was also a fun little bit of troubleshooting. After rebuilding the oscillator circuit I noticed that applying power to the "on the wall" amplifier caused the oscillator to shut down. At the buffer, I was seeing RF in and RF out, but the whole thing would shut down when I powered up the next stage. Obviously there wasn't a lot of BUFFERING going on! Sure enough, the MPF102 was bad. I replaced it from my dwindling supply, and all was right with the universe.

Now the amp goes in. But first I will build the low pass filter. I promise.

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Steve Jobs (age 12) calls Bill Hewlett (of HP)

"When he was in eighth grade, Steve Jobs decided to build a frequency counter for a school project and needed parts. Someone suggested that he call Bill Hewlett. Finding a William Hewlett in the telephone book, the 12-year-old Jobs called and asked, "Is this the Bill Hewlett of Hewlett-Packard?" "Yes," said Bill. Jobs made his request. Bill spent some time talking to him about his project. Several days later, Jobs went to HP and picked up a bag full of parts that Bill had put together for him."

More HP stories: http://www.hp.com/retiree/history/founders/hewlett/quotes.html

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Halloween Sale on SolderSmoke -- The Book

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Better Link to 1932 Yardley Beers Article

(From the November 2004 issue of QST)

I hear that picture I posted of the 1932 newspaper article was pretty much illegible. Sorry about that. Try this one from the Delaware Valley Radio Association. Scroll down a bit until you see OM Yardley in his front bedroom shack (the one with a window on the world!). On my Firefox browser I was able to click on it and get an easily read-able view.

http://photos1.blogger.com/blogger/2790/1877/1600/Yardley%20Beer%20DVRA1.jpg

Thanks DVRA!

BTW: Did you catch the name of the fellow who taught young Yardley the Morse Code? Atherton Noyes. Such good strong names!

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More on Yardley Beers

Just click on the article and use the zoom feature of your browser to visit the teenage shack of Yardley Beers.

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

Homebrew Hero: Yardley Beers

How's that for a beautiful homebrew rig! Prompted by our discussion of distinctive ham radio names, Harv, WA3EIB, sent us a very nice report on Yardley Beers, W0JF. The rig pictured is Yardley's "Jason" 20 meter QRP transceiver. Yardley had named the rig for his cousin. Harv met Yardley at a Colorado hamfest in 1993:

"On the table in front of Yardley was an Aluminum Box fashioned into a QRP radio named, “Jason”, 2 broken and worn head phones from the 1920’s, a few 1980’s QST and, several odd radio parts. My bulb of brilliance was not working that day. I said, “I don’t know what I’m looking for!" Somehow Yardley must have studied my eyes. I had locked my vision onto his very elaborate QRP rig. He paused for a few moments and said, “You into QRP?” By this time I felt more relaxed because he was now on my wavelength. I said, “Why yes, I would rather work with a homebrew radio that the ones with features that no one seems to know what they do!”

Harv bought the Jason (and everything else on Yardley's table) and established a lasting friendship with W0JF.

There is a nice article about OM Yardley's life in the November 2004 issue of QST.

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Steve Jobs and Heathkit

James, WL7FC/VE3ELI, sent us this clip from a Macleans article. Thanks James.

"His dad, though, was not his only early influence. In those days, the neighbourhoods of Silicon Valley were crawling with techies and engineers conducting cutting-edge work for firms like Hewlett-Packard and the Shockley Semiconductor Company. One of them was Larry Lang, who lived a few doors down from the Jobs house. Steve spent almost as much time in Lang’s garage as his own, tinkering with electronic equipment and assembling “Heathkits”: mail-order products such as amateur radios and receivers that took many hours—and much patience—to put together. Jobs would later say that those Heathkits helped him realize that everyday appliances, like the television in his living room, were not “magical” creations. “It gave [me] a tremendous level of self-confidence, that through exploration and learning one could understand seemingly very complex things in one’s environment,” he said. “My childhood was very fortunate in that way.”"

http://www2.macleans.ca/2011/10/17/thinking-different/

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Oh No! Short Circuit Danger with Anodized Heat Sinks?

Our friend Brent out in Minneapolis sent me some pre-Halloween HB frights yesterday. I'm still concerned. Am I living dangerously with my anodized but collector-connected heat sinks glued to the ground plane?
What say the HB gurus?

--- On Tue, 10/18/11, KD0GLS wrote:

From: KD0GLS Subject: Re: JBOT Amp
To: "Bill Meara"
Date: Tuesday, October 18, 2011, 9:38 PM

Bill,

Well, it is nearly Halloween, but it wasn't my intention to frighten you!

I think it's hard to argue with the fact that it works as-is. The heatsinks you bought look like common anodized aluminum to me. Out of curiosity I dug a couple of similar ones out of my parts bins and measured them. I found exactly what you did - wide open on the surface, and, not surprisingly, a dead short just underneath. I've always assumed that anodize finish was metallic and conductive, but now I know otherwise. I like to learn at least one new thing each day, so thanks for providing today's opportunity!

The clearances are no doubt small, but I think with the low voltages present in your circuit you'll probably be fine. The only potential problem might be if movement or vibration might someday break through that coating. I'd certainly recommend a fuse in the power supply line if you don't already have one.

Anyway, it looks great sitting there in the middle of your old rig. It's inspiring.

Brent

On Oct 18, 2011, at 19:42, Bill Meara wrote:

Brent: You scared me with your question but I think what I did is OK. Maybe. I looked more carefully at the clip on heat sinks I bought. They are covered with a non-conductive coating, but f I scratch them up a bit I can reach the conducting part. So i guess you just have to treat them gently if you intend (as I did) to super-glue them to the PC board. I notice that Farhan did the same thing (see his JBOT page) so I guess I'm OK. I put some heat sink compound in there too. And then there is the super glue. I have no short circuits from the collectors. I guess I could have used a Dremmel to isolate the copper just below the transistors. Or I could have put some mica between the heat sinks and the boards.

The sinks are deeper than the transistors, so there is no direct contact between the top of the transistor and the PC board.

What do you think?
--- On Tue, 10/18/11, KD0GLS wrote:

From: KD0GLS >
Subject: JBOT Amp
To: "Meara Bill" >
Date: Tuesday, October 18, 2011, 5:27 PM

Bill,

The amp looks mighty FB, and maybe I should try it as well. But I'm curious how you've insulated the collectors of all those transistors from the ground plane. From the picture, it looks like all of the metal heat sinks are sitting right on the ground plane copper.

.73,

Brent, KD0GLS, Minneapolis

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My JBOT 5 Watt Linear (Farhan's Design)

There it is -- my version of Farhan's JBOT 5 watt linear amplifier. JBOT stands for "Just a Bunch of Transistors." But I think Farhan is being modest. I really like the design, especially the effort to make this something that hams around the world can reproduce from readily available parts. For example, Farhan's original version used TV balun cores for the transformers. I didn't have any of those around, but I found three "mystery spec" binocular cores in my junk box. They seem to be working just fine. (I tested them a bit: Farhan had written that FT 37-43 cores would work. T1 has seven turns trifilar. Seven turns on my mystery cores yielded 13uH. On an FT 37-43 core 7 turns yields around 20 uH. Close enough -- these are, after all, broadband transformers.)

Note how closely my build follows Farhan's schematic (which you can see in the background). When building this circuit, I just kept Farhan's web page on my computer screen, and scrolled up and down from his schematic to the photo of his version.

This is the first linear amplifier that worked the first time I powered it up. It didn't release any smoke, or leave transistor burn tattoos on fingers, or try to be a 14MHz oscillator.

This version is going into my Azores-built 17 meter DSB transceiver. See how nice it fits:
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My JBOT passes the Smoke Test

Over the weekend I built my first version of Farhan's JBOT. I really enjoyed building it. I soldered in the last connections this morning and I am happy to report that it passed the smoke test. More info (and a picture) tomorrow. Thanks Farhan!

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