Listen to Latest SolderSmoke Podcast

Friday, May 2, 2008

Old Stuff from Gadgeteer News

February 23, 2007

I0ZY's Linear Amplifier

The WA7MLH Channel on YouTube (Recommended!)

February 16, 2008

The Rome operating position. The HW8 is currently my main rig. The Drake 2-B awaits new tubes from AES. The copper-clad
box is a homebrew 20 meter DSB transceiver using ceramic resonators and (mostly) NE602 chips. It awaits sunspots, but has yielded some great local QSOs in Rome . You can see my homebrew antenna tuner behind the straight key (with Vibroplex base). Also check out the very old Hi-Z headphones.


February 10, 2008
Amazing K7AGE Video of HARP HF Moonbounce
Check this one out. Not exactly QRP (!) but very interesting. At first the reflection signals are hard to hear, but hang in there,
they get a LOT stronger, and you can see them on Randy's computer screen.

January 25, 2008
VIDEO: WA7MLH Builds A Superhet Receiver
Jeff, WA7MLH, assisted in the construction of many of the projects in "Solid State Design for the
Radio Amateur" (SSDRA). I always liked the "ugly" "real world" look of his projects -- in contrast, some of
projects in the Handbooks looked like they'd emerged from a NASA clean room, not a ham shack. Continuing
in this tradition, Jeff has produced a very interesting YouTube video on a superhet receiver that he put together
largely with parts and circuits that were already on his workbench. FB.
Also be sure to check out Jeff's web site. The projects are both inspiring and intimidating! I really like the
audio explanations that he has alongside the photos. Thanks Jeff!
WA7MLH's Ham Radio Web Site
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January 24 2008 Steve, G0FUW, was recently listening to SolderSmoke at this location.
That's ZD8, Ascension Island in the South Atlantic. Check out the antenna farm. Thanks Steve!

January 24, 2008
Very well-done Hi Altitude Balloon Project Page

January 23, 2008
"A Nonlinear History of Radio" by T.H. Lee. Very FB!

January 12, 2008
SPRAT 99 (Summer 1999) has an article by Leon Williams, VK2DOB, that I think
does a great job at graphically describing how a mixer circuit produces both sum and difference
frequencies.


mixer

mixer

January 5, 2008

As part of an effort to understand mixers, I built a little circuit in LTSpice. Just two audio signal generators and three resistors. Surprisingly,
this thing seems to produce a "beat" or difference frequency. We've been discussing this on QRP-L and the G-QRP list. Here are some
screenshots of my LTSpice simulation. In the waveform shot, you can see how the phase differences of the two input waves combine to
produce the beat. I subsequently learned that this is not like a mixing product. It is not "extractable."


January 4, 2008
SCI-TOYS
Stewart, G3YSX, sent us the URL for a very interesting web site. Check out the
Morse communicator project in the computer section.
SCI TOYS
For similar stuff, check out "Gonzo Gizmos," available from the Gadgeteer bookstore (above).

SETI NEEDS YOU!
Ask yourself: Are you doing your part in the search for extraterrestrial intelligence? Berkeley wants you!
(I just signed up.)
How to put your computer into the SETI project


January 2, 2008
HOMEBREW TUBES
I really liked this video. The guy who made it has obviously mastered multiple difficult
crafts, including glass blowing, metal work, chemistry, electronics... Also, the video
itself is very well done, with really nice music in the background. Don't miss this one.
Video on homebrew tubes (valves, firebottles, etc.)

December 26 2007
Trailer for "The Dish" A movie about an antenna!
Buy "The Dish" here at the Gadgeteer Bookstore



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December 25, 2007 Some Stocking stuffers from SolderSmoke!

Bollywood Madness

You guys are probably sick of hearing about my appearance in the Bollywood movie "Cheeni Kum," but it just keeps getting
better and better. In the course of trying to post the trailer for the movie, I discovered that I not only made it into the film, but that I also made it into the trailer! On the You Tube clip, you'll need to put the video on "full screen" (click on the little box in the lower right of the video screen -- next to the volume control) then freeze the action at around 54 seconds. I'm the guy in the blue shirt in the Starbucks on the left of the screen. In SolderSmoke #73 I'll tell you about a connection between all this and the BITX-20. By watching the trailer you'll also get a sense of what modern Bollywood is all about.
Bill in Bollywood! Cheeni Kum Trailer! I'm in it! Check it out

VATICAN ANTENNAS

Looks to me like some sort of Streba Curtain array. This thing is only about 15 miles from our place in Rome. I want to visit!
Vatican Radio's HUGE SW Antenna Farm (near Rome)
Google Earth Location Info Look a bit north of the town of Santa Maria di Galeria and you should see the antennas.

ANTARCTIC IT
I found this very interesting. I liked the idea of salads produced in hydroponic gardens during the depths of the Antarctic winter.
Interview with IT manager at South Pole

RADIO CLUB OF AMERICA

What a great organization. Check out the history pages.
The Radio Club of America (check out the history pages!)


CIRCUITS, POEMS, PHILOSOPHY

Mike's pages are a wonderful mixture of interesting circuits, poetry, and philosophy. I nominate him for the position of
QRP Poet Laureate.
Michael J. Rainey: Poetry, Math, Philosophy and QRP

Acoustics, Vibrations, Waves, Beats, etc.
Some really great animations on this site by Dr. Dan Russell. This is related to our discussion of mixers.
Acoustics, waves, vibrations. Some animations.

Marconi making a speech in 1931
I thought this was interesting.
Marconi Speech

You Tube Computer History Museum
Mentioned on SolderSmoke -- Interesting Clips

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November 30, 2007

3D Software Model of Altoids Tin

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November 25, 2007 GOOGLE GADGET FOR SOLDERSMOKE FANS!

Google now allows you to create "gadgets" that people can place on their individualized iGoogle home pages.
For example, on my iGoogle page, I have a map that constantly shows the position of the International Space Station. I also have various news service, weather reports from places of interest, Dilbert, etc. Yesterday I created a Google Gadget for SolderSmoke. I'll use it to announce new editions of the podcast, updates of GADGETEERNEWS, etc. Be sure to include it on your iGoogle page. Google says it will appear in their directory within 10 days (search for SolderSmoke). If you can't wait that long, e-mail me and I'll send it to you.

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July 2007, San Diego, California
W7ZOI and N2CQR (with SSDRA in hand)


Wes and Bill in San Diego

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17 June 2007
SUPPORT SETI -- Help with some REAL DX

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16 June 2007
GEEK CORPS!
You've heard of the Peace Corps -- Check out the Geek Corps

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16 June 2007
SHOP CLASS AS SOULCRAFT
An excellent article by Matthew B. Crawford

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2 June 2007
Farhan's Blog
We're all very fortunate that our friend Farhan has set up a Blog. It is already full of interesting info. I especially liked his first article on minimalist tools for the homebrewer. Check it out! Spread the word! Post comments on the blog.
FARHAN'S BLOG
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2 June 2007
Amateur Logic TV. Like SolderSmoke but with video!


26 May 2007
FREE Technical Books online
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26 May 2007
The Milton Keynes Club BITX80 Project


20 May 2007
G3XBM's Site: Fredboxes, HF Crystal Receivers and more
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19 May 2007
Hewlett, Packard, Terman, and garages

Hewlett's Audio Oscillator -- used by Disney for Fantasia
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12 May 2007
HELP WANTED: SOLDERSMOKE CORRESPONDENT FOR DAYTON HAMVENTION AND FOUR DAYS IN MAY
The sad fact is that most of us won't be going to the big hamfest and the Four Days in May event. But if you are going, you can help your Dayton-deprived SolderSmoke brothers. You could become SolderSmoke's correspondent in Dayton. We're looking for someone who would be willing to record some short audio segments that would be included in the show. Segments 5-10 minutes long would be ideal. Interviews with homebrew and QRP leaders would be very interesting. Just send me the .wav or .mp3 files and I'll put them on the show. Perhaps just figure out how to use that record feature on your MP3 player, or bring along a small audio recorder. We don't want the Hamvention clogged with multiple SolderSmoke journalists, so we will be selecting only one or two OFFICIAL correspondents. If you are interested in doing this, send me an e-mail. Thanks!
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12 May 2007
KX4OM's excellent page on the W7ZOI power meter

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6 May 2007
SolderSmoke Book of the Week: As discussed on the podcast.

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5 May 2007
"FROM CRYSTAL SETS TO SIDEBAND" A GREAT BOOK BY FRANK HARRIS,
K0IYE FREE!

A wonderful and informative book for the homebrewer
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5 May 2007
FRANK JONES FMLA ARTICLES -- THE COMPLETE COLLECTION
Thanks to WB0AUQ for providing us these articles
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29 April 2007
THE JAMESBURG DEEP SPACE DISH PROJECT
Hams restore Apollo-era dish, use it for moonbounce!
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27 April 2007
"SIMPLE TEST EQUIPMENT FOR THE QRPer" by Graham Firth and Tony Fishpool
As discussed in SolderSmoke 54. Highly recommended!
Order the book here
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26 April 2007
THE ELSER-MATHES CUP: THE PRIZE AWAITS! DON'T MISS OUT!
The Ultimate (well, I guess not really ultimate) DX Award
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26 April 2007
A DIFFERENT KIND OF HOMEBREW (for SERIOUS DX)

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25 April 2007
SEMI-HOMEBREW 100 Mhz Digital 'Scope -- for $78
Interesting Oscillosope project

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25 April 2007
FMLA SAMPLE
I mentioned the Frank Jones "FMLA" series of radio fiction article by Michael Hopkins, AB5L, SK. Here's a sample. You can find more via the QRP-L archives.

... Frank is all homebrew. His receiver is unshielded outside, but built around a central square of aluminium that houses a Velvet Venier dial thru the front panel and some tubes I did not recognize jutting horizontally on both sides of the box where coils also plug in. The transmitter is a multi-stage affair on a piece of particle board. The tubes are vertical here, and the bench was littered with brown Hammarlund coils labeled 5, 10, 20, and 80. The 40M coils were in place and Frank worked a few stations at dizzying speed with a J-38. He never used the same call twice, and when he offered me a turn, I declined. The only transfomer in the place was on a small screen modulator attached to a pair of TH-100s labeled "PA" in the rack below the new-as-tomorrow computer. He seemed to be taking all his DC off the three-wire service line that entered thru a large piece of plastic DWV pipe and where, in turn, a run of fiberoptic snaked out and disappeared along a railroad right of way. I eased toward the back of the trailer, but Frank ignored the hint and suggested lunch.
As we took our leave the WARmon resumed his post at the gate and Zack began burrowing a small hole in a sack of Vital Varmit Dog Food. I never saw a canine. Frank drove to a a place called Pancho's Villa where he was well known and greeted with cries of "Vato!" I agonized with the menu's contorted Tex Mex, but Frank ordered menudo, rice and beans like a native. Indeed, in this enviornment his double-breasted suit did not seem so out of place, and when he parked, the Frazier drew a cadre of youths saying "Looks Charp" and "How High will it jump/"
"These are good people," said Frank, " and they recognize the value of improvosation." "They are not like modern hams who cannot homebrew a CPO without a PC board," he continued and , once again, he warned that when, as he says,"the balloon goes up" a lot of "KA this(s) and Vanity thats" won't be in those chosen to retake 5 Meters. On a more personal note he said my efforts at converting an old SCR-522 receiver were a good start and, when we left and said goodby at the Airflow, he procured from a plastic storage case under the napping Zack a Standard Coil tuner from a TV set long departed. "The old VHF Handbooks show how to make these into a converter," he said, "See what you can do with it."
I reflected on the way home that while Frank is truely a nut, he is also like the hams I knew when I was a kid. Those were guys who could "fix a radio" as the neighbors said, and we are someting else. Toying with the tuner, I found a note from Frank inside. "Don't change the Channel 2 part," It read.

73 de ab5L, michael in Dallas, student of Six Meters' Golden Age, 1957-58, and two of its jewels: Tecraft and International Crystal ham products. Michael N. Hopkins Box 226841 Dallas, TX 75222 MNHopkins@Juno.com
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6 April 2007
ITALIAN QRP CLUB CARRIES ARTICLE BY MIKE, KL7R
Ivan, G0BON, alerted me to the fact that the I-QRP club has included one
of Mike's projects in its April 2007 magazine. Mike would have been
very pleased. Grazie! By the way, the magazine looks very nice. I am really grateful to Ivan
for sending me this. I am studying Italian now, and the magazine lets me combine language study and
QRP reading.
Mike's article in the I-QRP journal.
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6 April 2007
NJHR 040107 CRIMINALIZES SOLDERING IN THE HOME! ?
The most important thing about this law is the date on which it was announced on SolderSmoke (note the number of the bill). Here we
simply participating in an old April tradition in ham radio. I hope the Trenton post office recovers from the flood of angry letters!
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6 April 2007
PA0CHN HOMBREW SSB TRANSCEIVER
Mike, EA8EQ, alerted me to this one. Very interesting.
PA0CHN Homebrew Rig
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1 April 2007
FO-29 SATELLITE: FEATURED ON THIS WEEK'S BANDSWEEP
Background info on the satellite
Thanks to Ray Benitez, M0DHP, for this first ever guest edition of Bandsweep.
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1 April 2007
JEAN SHEPHERD, W9QWN, K2ORS
Through his nightly program on WOR-AM in New York, I got interested in ham radio. Through this site,
you can listen to the old programs. Use the search feature to get to the shows that deal with ham radio.
I suggest plugging "Jean Shepherd" into the "artist" field, and "radio" into the "topic" field.
The Jean Shepherd Audio Archives
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26 March 2007
STORE THAT SELLS PARTS FROM THE SPACE PROGRAM
If you don't feel the urge to visit this one, you are not a gadgeteer
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March 25, 2007
JEFF DAMM'S INSPIRATIONAL WEB SITE
Great HB stuff from an SSDRA collaborator. Be sure to check out the audio!
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March 25, 2007
ABOUT SOLDERSMOKE'S NEW MUSIC
Beginning with #50, we are using custom-made theme music provided by Mark "Moj" Johnson. Mark explains how it was made: "In the homebrew spirit, I tried to make all the sounds with instruments which I had soldered together myself. These were a Formant music synthesizer designed by C. Chapman from the Dutch/British "Elektor" magazine, circa 1977, and a FatMan synthesizer kit from PAiA Electronics. I play them through an ancient Kustom 200 guitar amplifier, which I've caused to smoke at least twice. The beginning is my K2 being powered on and tuned across 80 meters. I cheated and used a real gong at the end which a good friend went to the trouble of finding and buying in China, but I fed the sound through a PIC Polywhatsit designed by John Becker and described in Britain's "Everyday Practical Electronics," December 2001. If anyone wants to sing along, it seems to me that the words are: ' - Sol-Der Smo-Oke, - Sol-Der Smoke (repeat over and over) ' Music, like all home-brew, is never truly done. Next time I'll try to get a theremin working again - there's a radio-circuited musical instrument!"
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March 24, 2007
WHATEVER HAPPENED TO THE ELECTRONIC HOBBYIST?
An article that will be of interest to all gadgeteers
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March 15, 2007
ANTIPODAL MAP TOOL
Find out what's exactly on the other side.
http://www.ubasics.com/dighole/
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March 3, 2007
MELTING SOLDER (VIRTUAL AND REAL!)
I'm continuing to work with feedback amps, first in LTSpice and then on the actual workbench. After building the second stage
on this amp, I noticed that I wasn't getting as much output in the real version as LTSpice was predicting. Poking around a bit
with my 'scope (the real one!), I noticed a lot of RF on the 12V DC line. This was before I added the C7 bypass cap.
After I put C7 in, the RF on the Vcc line disappeared and output was pretty much as predicted by LTSpice. I think this illustrates the
sthengths and weaknesses of the simulators. Even without C7 in the Spice model, the model showed no RF on the 12 V line. But in the real
world it was there. Here's the circuit so far. I am feeding it with the output of ceramic resonator oscillator.

Schematic
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28 February 2007
HOMEBREW CONTESTS
Fame and fortune could be yours! Check out these two homebrew competitions. Thanks to Frank, VK2AKG, for alerting us to them.
Spectrum IEEE contest

New South Wales contest
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25 February 2007:
SolderSmoke 47
It was with a heavy heart that I recorded the first ever solo edition of SolderSmoke. I
realize that it isn't even remotely as good as the earlier editions, but I was getting a lot of "I really miss SolderSmoke" messages, and I could almost hear Mike urging me to "do another one." So there it is. I'll try to line up some regular guests (the episode with Farhan was very popular) so hopefully soon we'll see the end of my mono-tone monologues.
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21 February 2007
GREAT BITX20 SITE (WITH VIDEOS)
Leonard, KC0WOX, has put together a great site describing his experiences with the world famous BITX20 transciever (from India). He has
two videos, one describing AM and DSB modulation, and one about building crystal filters.
Click here to check it out. The video links are at the bottom.
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11 February 2007
OUR FIRST ANIMATION
Billy and I tried our hand at making a simple animated video clip. We're a long way from Disney quality, but it did work!
We used a digital camera and Windows Movie Maker. It runs for 4 seconds. Check it out.
Billy and Bill's First Amimated Clip!
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10 February 2007
GADGETEER BOOKS
I just launched an online book store intended to be of interest to Gadgeteer and SolderSmoke fans. Here's the deal: I provide book suggestions and short reviews. If you go to Amazon via one of my links and buy something, Amazon sends me a bit of money for the adverstising. My ambition is to cover the cost of the web hosting and domain registration for Gadgeteer and SolderSmoke. GADGETEER BOOKS -- BILL'S ONLINE BOOK STORE
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10 February 2007
Laser computer link
On SolderSmoke we talked about using lasers for communication. Here's a neat plan for using ordinary laser
pointers to link two computers. Thanks to Hack-A-Day for alerting me.
http://www.geocities.com/SiliconValley/Lakes/7156/laser.htm

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22 January 2007
LTSpice Circuit Simulator
We've been talking about the LTSpice program. Nick Kenndy, WA5BDU, has some very good info about this amazing program
on his web site. Nick wrote a short guide to LTSpice for beginners that I found very useful. Click here for Nick's site.
Thanks Nick!

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14 January 2007

LIQUID OXYGEN
I just have to share this. We were walking through Chelsea (London) this afternoon , en route to St. Luke's park where we intended
to launch a vinegar and baking soda rocket. I was telling my son about the fuel system used in the Saturn V -- liquid oxygen and all that.
He asked, "Dad, can they really turn oxygen to a liquid?" At that moment, we tuned the corner and came around the back of Marsden
Hospital. I looked up and saw in front of us a huge tank marked "LIQUID OXYGEN." Wow, perfect timing. I eve had the chance to
point out that widespread availability of pure oxygen in hospitals is an Apollo spinoff. (Our rocket launched spectacularly!)
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13 January 2007
MY EXPERIMENTS WITH FEEDBACK AMPS
I've been trying to improve my understanding of amplifier design. I start with SSDRA and EMRFD, then do some initial design on paper,
then proceed to a simulation in LTSpice, then I actually build the thing on the workbench. There is a lot of complexity in even a very simple
amp. Wes, W7ZOI, (one of the authors of SSDRA and EMRFD) has been kind enough to help me, and he sent comments on my latest
effort. Here they are, in .pdf form. Thanks Wes!

Wes, W7ZOI, comments on feedback amp

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13 January 2007
MICHIGAN MIGHTY MITE
Mentioned on SolderSmoke #46. Here it is. Experience the joy of oscillation!
Michigan Mighty Mite QRP transmitter

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4 January 2007
GOOD CONDITIONS ON 17 METERS
I started the new year off with a touch of the flu, but every dark cloud has a silver lining. I was able to
get on 17 meter phone when conditions were good. With my 5 watt homebrew SSB transmitter I managed to
talk to WB3ANT in Pennsylvania on 4 January. It had been a long time since I'd had a transatlantic contact.
I've also been hearing lots of DX on 17 during the day, including Australians and Falkland island stations.
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23 December 2006
VIDEO OF THE FOOL'S GOLD CRYSTAL RADIO IN OPERATION

Fool's Gold Crystal Radio Video

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22 December 2006
MIKE's LT SPICE INTRO VIDEO
Check out Mike's very informative video explaining how to use the (free!) LTSpice circuit simulation program. Be
sure to click on the little green arrows when they appear (they just pause the video).

Mike's Intro to LTSpice video
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17 December 2006
CRYSTAL MADNESS
It turns out that the station we are listening to with the crystal radio is Kismat Radio, 1035 kHz in London. It serves the Asian community and broadcasts in a number of languages of the sub-continent. (It is a very nice station, and we enjoying it. The Bollywood music is great!) This morning we experimented with a few different detectors. I pulled out an old galena and phosphor-bronze cat's whisker detector. My son found the sweet spot, but the signal level was significantly lower than that of the germanium diode. Next we tried an LED. No joy there -- I think the threshold voltage for this device is too high for our purposes. Finally, I dug up some "fools gold" that we had bought in the London Natural History museum. With the phosphor bronze cat's whisker, this worked almost as well as the germanium. I have the receiver feeding a little amplified computer speaker. Kismat radio is rocking the shack!
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16 December 2006
CRYSTAL RADIO ADVENTURES
Inspired by Rick Campbell's minimalist radio post (see below), my son and I built a crystal radio this morning.
Just an LC circuit with a coil wound on an old plastic bottle (Re-Nu!) and a variable cap. Germanium diode
detector. Hi Z headphones. Antenna is my 20 meter vertical. AM broadcast stations coming in very loud and clear. Check out the recording at the link below. This was made just by holding the computer mic to the old headset. Is that Hindi?

Listen to a few seconds of the audio from this receiver

xtal radio
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1
4 December 2006
HACK-A-DAY DESIGN CONTEST
Just 12 days left! Don't miss out!
Hack-a-day design contest

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13 December 2006
MIKE'S LTSPICE VIDEOCAST -- RETURN LOSS
Check out Mike's excellent video showing his work on return loss calculations and input/output impedances using LTSpice.
Be sure to click on the green arrows when they appear. Mike's file is very skinny -- only 2.5 megs.

Mike's return loss LTSpice video-cast

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10 December 2006
FIRST LTSPICE VIDEOCAST
I made a 5 minute video using a video screen-capture program and the circuit simulator LTSpice. In addition to showing how LTSpice can
be used, the video looks at how saturation affects the efficiency of Class C amplifiers. I put the file on YouTube, but the video quality is poor when viewed through that service (it is difficult to see the graph lines in the YouTube version). So I have also uploaded the 26 meg file (.wmv)
to the http://www.gadgeteer.us web site.

Click here for the direct download of the .wmv file

Click here for the YouTube (lower quality) version

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7 December 2006
BOOK RECOMMENDATION
If you like SolderSmoke, you'll love Gonzo Gizmos. Lots of great projects, including radio stuff. The author does a wonderful job of mixing construction information with scientific theory. I found my copy in a comic book store
in London. Link to Amazon.com on the left.
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4 December 2006
HOMEBREW TUBES
“A young lad of seventeen, known to possess an especially efficient spark, cw, and radiotelephone station, was discovered
to be the son of a laboring man in extremely reduced circumstances. The son had attended grammar school until he was
able to work, and then he assisted in the support of the family. They were very poor indeed. Yet despite this, the
chap had a marvelously complete and efficient station, installed in a miserably small closet in his mother’s kitchen.
How had he done it? The answer was that he had constructed every last detail of the station himself. Even such
complex and intricate structures as headphones and vacuum tubes were homemade! Asked how he had managed
to make these products of specialist, he showed the most ingenious construction of headphones from bit of wood
and wire. To build the vacuum tubes, he found where a wholesale drug company dumped its broken test tubes,
and where the electric light company dumped its burnt out bulbs, and had picked up enough glass to build his
own tubes, and enough bits of tungsten wire to make his own filaments. To exhaust the tubes, he made his own
mercury vacuum pump from scrap glass. His greatest difficult was in securing the mercury for his pump. He
finally begged enough of this from another amateur. And the tubes were good ones, better than many commercially
manufactured and sold. The greatest financial investment that this lad had made was 25 cents for a pair of
combination cutting pliers. That is the spirit that has made ham radio.”
From “200 Meters and Down –
The Story of Amateur Radio” By Clinton B. DeSoto, published in 1936 by the Amateur Radio Relay League, Inc.
West Hartford, Ct. pp 63-64
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3 December 2006

FEEDBACK AND INPUT IMPEDANCE
WHAT BILL WAS STRUGGLING WITH ON SOLDERSMOKE #42


I think it was just too early in the morning for thinking about this kind of issue. Why would placing a feedback network between the
collector and the base of a common emitter amplifier decrease the input impedance? This is what I wanted to understand. I thought I
did, but then I couldn't explain it. That made me realize that I didn't really understand it.

Understanding came to me today while my daughter was playing on a swing in a London park: Imagine this circuit: Common emitter, NPN transistor. Imagine the input signal in the positive half of the cycle. During this part of the cycle, the input signal will be pulling electrons up through the base-emitter junction. The amount of current that will be generated by a given input voltage will define the input impedance.

Remember that the voltage at the collector is 180 degrees out of phase with the input signal. When the base is in the positive portion of the cycle, the collector is in the negative portion. If we use a feedback network to put some of this negative collector voltage on the base, the amount of current drawn out of the circuit will increase. You have just connected the electron deficient (positive) input signal to the electron rich (negative) collector signal. With the collector to emitter feedback network, the input voltage will pull more current out of the device than it did without the feedback network. More current flowing for a given input voltage indicates that impedance has dropped.

For some reason the explanations in the literature never made it clear to me WHY this kind of feedback lowers the input impedance. Now I understand it. (I hope!)

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3 December 2006
A FEW THOUGHTS ON MINIMALIST RADIO FROM KK7B
(Originally posted on the EMRFD Yahoo group)

If you really want to do minimalist radio, you may want to step way
back and take a look at some very early history. The Pixie circuit
has many more components than an early CW station from the era
immediately after spark.

Rather than starting with the Pixie and trying to figure out what to
eliminate, maybe a better approach is to start from zero and decide
what you need. Combining transmit and receive functions is the last
thing to think about.

Starting with the receiver.... The first thing you need is wire up
in the air. The more, the better. If you have the real estate for a
full sized dipole on 80 meters, you can collect enough signal energy
to hear on a crystal set when conditions are good. I've copied CW
signals on 40 meters with just a dipole, transmatch, a 1N34 diode, a
good pair of headphones, and a one transistor Pierce oscillator
running on the bench. The leakage from the crystal oscillator picked
up by the antenna beats against the incoming signals. I didn't power
the oscillator with lemon juice, but I could have (see Bob Culter and
Wes Hayward, "Lemonized QSO" in March 1992 QST.)

Then for the transmitter, just heat-sink the Pierce oscillator and
key the connection to the load. The shift in load impedance will
offset the crystal oscillator frequency.

A dual pi-net transmatch configuration would take care of the
harmonics and allow maximum energy transfer between the antenna and
diode--but I'd analyze it to make sure the harmonic suppression is
more than legal.

So far I count 5 components for the dual Pi-Net transmatch, a 1N34
diode, 6 components for the one-transistor Pierce oscillator. A
dozen parts, plus headphones, a key, and battery--or some electrodes
to push into a lemon.

That would make contacts, but Wes and I have discussed a basic rule
for radios, which is that a station should be able to work an
identical station over a distance of a few miles. It could probably
be done with the above station, but a single transistor audio
amplifier running at maximum gain between the 1N34 and headphones
would make it possible to extract many more signals from the 80 meter
dipole. That's another 5 or 6 parts. So now I'm up to about 20.

For a more serious station, I'd probably add two more transistors and
a diode, so I could have a separate PA, a balanced mixer, and two
audio stages. The receiver would end up looking a bit like EMRFD
figure 8.7 with a PA tacked on. That would have about 35 parts, but
it would be able to work DX off the ionosphere...about the same
complexity and performance as many other variations on the theme. A
previous version of the Pixie from the 1970s was called "The
Optimist."

Unlike Muntz--instead of starting with someone else's circuit and
trying to eliminate parts until I had something that just barely
works, I'd start from scratch, study EMRFD (and other references too--
but in EMRFD all the circuits have been designed and tested) for
circuit ideas, and then start experimenting on the bench, one stage
and one component at a time. Since one of the joys of minimalist
radios is that they can be understood all the way down to the device
physics, I avoid ICs. (I particularly avoid cell-phone ICs, which I
designed for a number of years. It's like working in a sausage
factory--you are much happier if you don't know what's inside.)

Minimalist radio is one of the more interesting design games that we
play using the methods of EMRFD. It's cheap, it's interesting...and
as we dig in, we discover that the details can be every bit as
challenging for a radio project with 30 parts as one with 30,000.

Have fun.

Best Regards,

Rick kk7b

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3 December 2006
HERE'S THE WEBSITE FOR THE DIGITIAL MODE ID SITE
http://f1ult.free.fr/DIGIMODES/MULTIPSK/digimodesF6CTE_en.htm

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2 December 2006
NE602=NE612=SA602
(Originally posted on QRP-L)
Gang,
The ever famous NE602's are manufactured in the Philips
Semiconductor plant in Albuquerque, about 85 miles north of me. I visited
there last summer and had a nice discussion with an applications engineer
about the history of the NE602's. Goes something like this:

This long story will prove that NE602 = SA602 = NE612 = SA612
(for those of you who don't want the gory details -hi)
The original NE602 was designed/manufactured by SIGNETICS for
the 45MHz FM wireless telephone market. A little later, the wafer was
redesigned a bit to allow the internal oscillator to operate to 200MHz and the
RF to 500MHz. This was redesignated the NE612, and was intended to
replace the NE602. However, customers kept ordering the NE602, getting
angry at Signetics because their distributors were out of stock, etc. So when
they made the chips, they made a jillion NE612's, and labeled some of them
NE612 and the rest NE602 to satisfy the users of both parts. This is why
contemporary data books show the exact same specifications for both NE602
and NE612. They came from the same wafer.

Then Signetics was bought out by Philips, who evidently
continued this practice for a short time, then decided it was rather
redundant. So they announced that the production of NE602's has been discontinued
and listed it as an obsolete part ... giving QRPers around the world
various fits of apoplexy to suicidal tendencies that doomsday had struck.
What wasn't well understood is Philips continued to support production of
the NE612, as they do today.

Then to make matters worse, disaster struck the Philips plant
in Albuquerque in the spring of 2000. A wild grass fire in
northwest New Mexico threatened three main electrical lines that run from
the "Four Corners" electrical generating plant to Albuquerque. Smoke
from the fire caused one of the high-voltage lines to arc, tripping the
circuit off line. Virtually the entire electrical load for Albuquerque
and southern New Mexico was now transfered to the two remaining feeders,
which could not handle the full load, causing brownouts, voltage spikes,
etc. until they too failed. Where I live in Socorro, New Mexico, I
remember the brownouts hit about 4:15pm, outages on and off until the
entire grid went down about 5pm, and stayed off until about 11pm. One of the
longest power failures in US history. We just figured it was Y2K about 3
months late. (PS - I worked 40M CW QRP that night by candlelight, and it
was the quietest conditions I ever heard on 40M!!! And every QSO I
heard seemed to be a QRPer). The extreme voltage fluctations as the
feeders were failing caused a transformer at the Philips plant in
Albuquerque to catch on fire. I remember seeing it on the TV news, in which they
said it caused mostly smoke damage from the burning transformer and
burned a couple of storage rooms. That was all-no biggie. Well, it
turned out one of the storage rooms that was burned was where they stored
the film masters for making the semiconductor dies, and the NE612 film
master was now molten emulsion. These film masters were the originals
from the old Signetics company. So Philips had to completely redo the
artwork for the majority of their IC's. Additionally, it turned out the
smoke damage was excessive and the IC fabrication facilities were
left unusable. Philips was basically unable to manufacture IC's at
the Albuquerque plant for months. It was about 8 months before
they got all their wafer machines back on line, which left a huge hole in
the semiconductor industry. I know it just about killed several
cell phone manufacturers because delivery contracts for parts were
suddenly postponed for six to eight months.

The world wide supply of NE602/NE612's virtually dried up
during 2000 as a result of this fire and the nearly year backlog of
manufacturing quotas. The first run of NE612's in 2 years finally occured in
September 2000.This huge shortage of NE612's, combined with the fact that
NE602's have been discontinued/obsolete, is what convinved QRPers that
these nifty little chips were no more. I was told 20,000 units were
manufactured in 2000, or what Philips believes is a 2 year supply. This is
also why the release of the K1 (with 5 NE612's!) was delayed from the
promised "after Dayton" to late in the year, as were other kits. It just
wasn't clear when Philips was going to schedule the NE612's for production.

So yes, the NE602 is dead, but the perfectly compatible NE612
is still available, and Philips has no plans at the present to
discontinue that part number.

For final clarification:
NE602 = plastic DIP, rated 0C to +70C ... OBSOLETE
SA602 = plastic DIP, rated -40C to +85C ... OBSOLETE
NE612 = plastic DIP, rated 0C to +70C ... AVAILABLE
SA612 = plastic DIP, rated -40C to +85C ... AVAILABLE

or, to answer the final question ...
NE602 = SA602 = NE612 = SA612

72, Paul NA5N

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26 November 2006
GOOGLE EARTH SPOTS M0HBR'S LONDON ANTENNA!

Here's Google Earth's shot of our house in London. I was amazed to be able to see my fishing pole dipole! These are the same fishing poles that supported my 17 meter rotatable dipole in the Azores.

Bill's Antenna as seen by GoogleEarth

--------------------------------------------------------------------------------------------------------------------------------
25 November 2006
HAMFEST JUNK


Here's some of the gear I picked up at the Kempton Park (West of London) Hamfest.
Power Supply, Broadband amp built in tobacco tin, signal generator, book, magazine,
Hi-Z headphones, copper-clad board.

Kempton Park acquisitions

----------------------------------------------------------
27 November 2006

MICHIGAN TEEN CREATES NUCLEAR FUSION DEVICE

http://www.freep.com/apps/pbcs.dll/article?AID=/20061119/NEWS03/611190639

And I thought that my teenage adventures building a 1000 volt powers supply for an HW-32A were daring! Check out this kid's project.

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Designer: Douglas Bowman | Dimodifikasi oleh Abdul Munir Original Posting Rounders 3 Column