"The Little Sweetheart" Receiver

Wow, what a beautiful piece of work! And a fascinating story behind it, with hints of wartime romance... Thanks to Mike AA1TJ whose very eclectic reading (Czech tech mags!) led us to this. Thanks also the Crypto Museum. Here is the link:

http://www.cryptomuseum.com/spy/sweetheart/index.htm

With more info here:
http://antiqueradios.com/forums/viewtopic.php?t=96007
And here:
http://antiqueradios.com/forums/viewtopic.php?t=96057

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Amateur Radio Balloon Crosses The Pond (and the Continent)

Wow, congratulations to the California Near Space team. Their balloon flew from Silicon Valley, across the U.S., across the Atlantic and is now en route to Italy. As a former Azores APRS operator, I was pleased to see the APRS report from those islands. George, KJ6VU, of Sierra Radio Systems, was present for the launch.

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Have An Oz Knack Christmas with VK2ZAY!

This is not the most flattering picture of our friend Alan, VK2ZAY, but I find myself forced to use it (again!) because of the Christmas light head-gear. Sorry OM.

I was thinking about Alan just the other day as I contemplated my broken Lafayette power supply (scroll down to the test gear article). You see, the meter in that little supply was destroyed by a trivial electric motor that Billy and I built a long time ago after a visit to Alan's amazing site. Don't worry Alan -- the broken meter is not your fault.

Once again proving that he is a true Knack victim and a certified member of the International Brotherhood of Electronic Wizards, Alan is doing an "Advent Calendar" of YouTube tech videos -- one short video each day during the Christmas season. I looked at a couple of them this morning. You guys will love them. Alan obviously has a deep understanding of the circuitry and a great talent for explaining how his creations work.
Thanks a lot Alan! Here is the link:

http://www.youtube.com/user/vk2zay

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Seeing EM Waves with a Coffee Can

Thanks to Leif KC8RWR for alerting me to this. Amazing stuff, but somehow I think they need to get an Altoid tin into this project. You can sense the enthusiasm.

"Particles? We don't need no stinkin' particles!"

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The "Snort Rosin" Test Gear Philosophy

Steve Smith, WB6TNL, and I often find ourselves on the same frequency:

Hi Bill,

After reading your latest blog post, I realized that you and I are somewhat kindred spirits. You successfully build and test relatively complex amateur radio equipment using the most basic and inexpensive test equipment.

As part of my business (land mobile radio) I own expensive and complex test equipment, however when I build and test homebrewed amateur radio gear I prefer to use inexpensive home-built or kit-built test equipment because that is what is generally available to most hams. My philosophy is that it is very important to impress upon beginning homebrewers the fact that fancy, complex test gear is not absolutely necessary to be successful in homebrewing.

Perfectly functional test gear can be built using only basic electronic tools. Certainly, homebrewed equipment might not have all the 'bells and whistles' of commercial gear and won't do everything 'automagically' but with careful calibration and learning how interpret the results, homebrewed test equipment can provide very accurate measurements.

One good example is your Palomar R-X Noise Bridge. Most every ham wants a MFJ 259B or Autek VA-1 antenna analyser but an inexpensive bridge like the Palomar or a homebrewed equivalent can provide many of the same measurements. Sure, a ham-band or general-coverage receiver is required to use a noise bridge but, by using -very- simple circuits, a very competent test receiver can be built using the most basic test gear. Even with only a good SWR meter and a little math thrown in, +/- Xj (reactance) measurements can be made (See http://www.qsl.net/n8xpv/ for information regarding "the 3 meter method" ).

One of my favorite resources for simple test equipment is Monty Northrup's (N5ESE} site: 73.......

Steve Smith WB6TNL "Snort Rosin"

From:

"solder smoke"

To:

"Steve Smith"

Great message Steve. Yea, I think the best troubleshooting tool is a real understanding of what is happening (or supposed to be happening) in the circuit and an ability to think logically about what could be causing the problem. Technical detective work. And indeed, that SWR bridge can tell you a lot.
73 Bill

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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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