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Saturday, March 30, 2013

An update from Yi Yao, VA3YAO


We did a short article on Yi Yao a while back, noting that he definitely has The Knack.   His homebrew frequency counter (above) confirms that he does.   In a recent  e-mail from him I also detect an inclination toward poetry.  April is Poetry Month, so I thought I should share the latest from Yi:

Hi Bill,

I haven't gotten around to making my first rig yet. But, after
listening to SolderSmoke since the beginning, it seems like the universal rule
of homebrewing has been to avoid regens!

I've been focusing on mechanical design for the last while. Having
spent 2 years in a heavily electrical engineering oriented
environment, I decided to try something new.
Most of the smoke that

 I inhale these days is from cutting oil vaporizing as I turn something
on the lathe. Chips mean bits of metal that are created from cutting
metal. Soldering is done with a torch. The common thread with
electronics is the knackish pursuit of elegant design and beautiful
construction.


I've been thinking about getting myself a copy of SSDRA, but even
looking at online used book stores, this is costing in the
neighbourhood of some of my university textbooks. There's no shortage
of good information and ideas for homebrewing online though. I think
that's what I will use.

Cheers,
Yi



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Friday, March 29, 2013

Wow! Great Article on the Wow SETI Signal


Thanks to David Umbaugh (and his son!) for alerting me to this really great article in The Atlantic on one intrepid amateur who has chosen to follow-up on the famous (and possibly extraterrestrial) "Wow" signal.   You will like this article. 

http://m.theatlantic.com/technology/archive/2012/02/the-wow-signal-one-mans-search-for-setis-most-tantalizing-trace-of-alien-life/253093/


Robert Gray's book is available here:



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

Thursday, March 28, 2013

Good time to Buy Book: 20% off at Lulu

http://www.lulu.com/spotlight/soldersmoke

Use Coupon Code VERNUM through March 31 and get 20% off.

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

Edgy Skimmer Antenna


For the last few days I've been hanging out on 20 meter CW, 14.050 - 14.060 MHz, using my re-built W1VD/Barbados rig.   I've had some great contacts, but almost as  much fun is watching the Reverse Beacon Network to see who is hearing my calls.   WA7LNW is one of the "skimmers" that most consistently picks up my signal.  One look at the picture above explains this.  The receive antenna for his skimmer rig IS ON THE EDGE OF THIS CLIFF!   Jack has one of those dream jobs for a radio amateur:  he works at that amazing location, testing ejection seats for jet aircraft.  More great pictures here: 

http://www.dxwatch.com/qrz/lookup.php?c=rbn/WA7LNW

Thanks for the reports Jack!




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Wednesday, March 27, 2013

AA1TJ's Latest QRPp Rig

 
From Mike, AA1TJ:

I called CQ on 20m CW for a couple of hours yesterday afternoon with no response. With the cadence of my own Morse tugging at my eyelids, I was suddenly shaken awake by a brisk signal returning my call and signing CU2BV. I snapped out a 579 report and turned it over. The dits and dahs in my headphones told me it was Fernando; operating from São Miguel island in the Azores. He reported a weak but solid copy (529) of my fifty milliwatt signal.

Here's the radio that I used yesterday. The one-transistor transmitter is to the left of the red relay on the top board. The single transistor is a germanium surface-barrier device made by Philco in August of 1958. To the right of the relay is a two-transistor time-delay circuit used to switch the antenna between the transmitter and the receiver. My receiver on the lower proto-board is a reproduction of my first shortwave receiver: a $7 Japanese kit that I bought at Radio Shack when I was 13 years-old.

Fifty milliwatts is some twenty-four times less power than was used by an old double D-cell flashlight. I later learned that my signal was nearly simultaneously picked up by an automated receiver located just west of Dusseldorf, Germany.

Snowy Vermont to the lush Azores - some 1500miles off the coast of Portugal - with less power than is consumed by a beeswax candle...is it any wonder that I love radio? ;-)


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Tuesday, March 26, 2013

Sunblock! Earth-Sun-Mars Alignment Affects Communications


Something to be considered by those hoping to win the Elser-Mathes Cup.

http://www.jpl.nasa.gov/news/news.php?release=2013-108

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

Monday, March 25, 2013

Video of my Barebones Superhet







I literally blew the dust off this thing last week.  I posted the schematic a few days ago (scroll down).   This morning I finished re-building the CW transmitter that went with it.   I am running out of rigs to re-build, so I suppose I will now have to start building some new ones.  Maybe a BITX-20?  Or a BITX-75/20? 

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

Sunday, March 24, 2013

The Southern Appalachian Radio Museum



Chris, KD4PBJ, of SMT Solutions, sent us a thumb drive with pictures and videos of his visit to the Southern Appalachian Radio Museum.   What a great collection of radios!   I saw many old friends on those shelves.

There is a lot of radio history in that museum, and much of it is conveyed by the photos and videos that Chris took.   Here they are, all 111 files:

https://picasaweb.google.com/116927941005026017464/SARM#

The museum is in Asheville, N.C.  http://www.saradiomuseum.org 

Thanks Chris.  And thanks to the curators of this fine museum.

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

Saturday, March 23, 2013

A Beautiful Receiver by W1DN






I wish my prototypes (or final products!) looked this good.    I like the way Lee puts the switches onto the prototype board.  Very nice.

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

Wednesday, March 20, 2013

Wow! Raspberry Pi as an RF Transmitter


https://github.com/threeme3/WsprryPi

This site shows you how to use a $35 Raspberry Pi Computer as an RF transmitter for the WSPR (Weak Signal Propagation Reporting) System.  All you need is a simple low pass filter and an antenna. (Oh yea, and a ham radio license.)  The site says you can get 10 milliwatts out.  That's enough for WSPR!   Very cool. 

This looks like a real international effort:

Credits goes to Oliver Mattos and Oskar Weigl who implemented PiFM [1]  based on the idea of exploiting RPi DPLL as FM transmitter. Dan MD1CLV combined this effort with WSPR encoding algorithm from F8CHK, resulting  in WsprryPi a WSPR beacon for LF and MF bands. Guido PE1NNZ extended this effort with DMA based PWM modulation of fractional divider that was  part of PiFM, allowing to operate the WSPR beacon also on HF and VHF bands.

For more info on WSPR:  http://soldersmoke.blogspot.com/search/label/WSPR

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

Podcast Noise Explained; Mic advice from Germany


Hello Bill,

This might be down the drain for you, but I only listen to your podcast very few months:

The background hiss you mentioned in Soldersmoke 148 definitely was a crosstalk from the switching voltage converters for the CPU in your laptop. The CPUs these days are operated with voltages in the .7 V to  2 V range,with currents from several Amperes up. A high-performance CPU may dissipate150 W which can easily mean supply currents of 100 A an more. The CPU operating voltage, especially in a laptop, might change several 100 times a second. I think you can imagine the rest.

Why is that voltage adaption so important? This is within your domain: The biggest heat source in digital electronics these days is charging and discharging capacitors. Unless you use a resonant circuit (which you cannot do on a chip) you dissipate P = 1/2 C U^2 with every discharge. Yes: Power depends on the square of the supply voltage. And at a clock frequency in the 2 GHz range you charge and discharge all those capacitors quite often. Each of these has a capacity in the fF (.001 pF) range, but you have billions of these...

Over the time you had quite some complaints about your whistling s. In former times this was definitely made worse by some technical problems. But this is a problem long gone. An Soldersmoke 149 I believe the remaining problem simply was the tooth gap you described a few years back.


BTW: You could easily reduce the file sizes of your podcasts by at least 50% with a few simple measures:

- You should record the podcast as you do now, with a 44 or 48 kHz sampling rate, that's fine. I would even record in wave format.

- Afterwards downsample your recording to a sampling rate of 12 or 16 kHz. This provides ample audio bandwidth for this purpose. See e.g.
http://forum.audacityteam.org/viewtopic.php?f=28&t=19705

- Then create the MP3 file with a signal rate of 48 or 64 kbit/s.


BTW: Last weekend at a ham flea market I got a variable transformer. Now I can try to revitalize my Drake TR4C that has not seen any electricity for some 30 years. I bought it when I got my shortwave license in 1975. At that time I lived with my parents. Then I could operate it during my military service. But after that I got an electronics engineer and lost all possibilities to erect any kind of SW antenna. Only three years ago I got my own house near Munich. But I'm hardly at home and I nearly exclusively operate from my car. I will not try this with any kind of boatanchor :-)

vy 73
Alexander
DL4NO

------------------------------------
Von: solder smoke [mailto:soldersmoke@yahoo.com]
Gesendet: Dienstag, 19. März 2013 09:49
An: DL4NOAlexander
Betreff: Re: Soldersmoke 148: Background Hiss



Thank you Alexander.  That is very useful information.   I have switched to a new computer and I think the hiss  problem is gone.   The gap in my teeth remains however! 

 

I am thinking about getting a better microphone.  Any advice on this?

 

I am glad to  hear that you are back into ham radio.  My Elmer (the guy who helped me get started as a novice) was an immigrant from Germany (Hilmar,  WN2NEC).  He was an excellent technician.   I still use some of the things he made for me.

 

73  Bill
------------------------------------------------
Hello Bill,
 
about a microphone: Think about a headset, possibly a wireless one. I would search forums about dictation software for advice.
 
A headset fixes the position of the microphone relative to your mouth. At the same time the microphone is near your mouth so any ambient noise is suppressed. A wireless [Bluetooth] headset would allow you to move around freely. Unless you come near a larger hard or soft surface or leave the room the sound should not change much. You could arrange the materials for your next podcast around the room and move from "chapter" to "chapter". And as the digitizing happens in the headset all weak analog signals are safe away from any voltage converters and digital electronics.
 
I had never left ham radio, I just reduced and modified my activities. 2m or 70cm FM were always possible. Here in Germany we have more than 1,000 repeaters. Many of these repeaters have Echolink capabilities. For the last 15 years I have more or less exclusively worked from my car while driving. In my car I have a FT-857D. For shortwave I use monoband antennas on a PL mount at on the roof of my car. For pictures see http://www.dl4no.de/thema/amateur1.htm. The schematic in http://www.dl4no.de/thema/mobil-st.htm shows how I ensure that my TRX gets its 22 A peak from the 12V outlet in the trunk of my car: I buffer it with a 1 F capacitor - really 1,000,000 µF! The mean supply current during SSB transmit is less than 5 A.
 
A quite important role in my ham life play the local chapters of our German ham radio society DARC. There are more than 1,000 of them, each with its own DOK. So wherever my customers are, at least one local ham meeting a month is not far away. I participate in their activities, give a lecture from time to time. This is a big help as I mostly work at my customers and these are scattered all over southern Germany.
 
Just a short story with some local connection for you: Peter, DL5NC, spent quite a few years in the Washington, DC area. He has a US call, but please don't ask. He was born some 50 km from my home town. Formally this area, Franconia, has been part of Bavaria since 1806. Nevertheless we believe that the Bavarians have no clue how to brew beer.
 
One Friday morning (your time) he was on his way into Washington, DC. Through Echolink he connected to a Munich repeater while I was in the afternoon rush hour on my way to a beer garden. I told him that this was one of the few places in Munich where you could get a decent beer. And otherwise I had my own beer at home imported from Franconia. He threatened to never again talk to me because of mental cruelty. In the meantime he returned to Germany and got a neighbor. We drank a few Franconican beers together in the meantime :-)
vy 73
Alexander
DL4NO
 


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Tuesday, March 19, 2013

DeMaw's Barebones Superhet


A recent e-mail got me thinking about Doug DeMaw's Barebones Superhet.  June 1982 QST.  Mostly 40673 Dual Gate MOSFETS (this one's for you Dino!).  Barebones indeed.  Check out the schematic.

I literally blew the dust off my version and fired it up on Sunday.  It sounds really great.   I had lowered the values of the caps in the ladder filter to widen it out for phone.   Also, I see that I used LM386 instead of the op amp AF Amp prescribed by W1FB.   I notice that my version has much better audio than another version of this RX (with the op amp) that I'm using on 17 meters.  Could the difference be the LM386 vs. op amp?  There is a lot more audio with the 386, and the AF response seems wider.  

I feel the urge to put this receiver to use.  I am rehabilitating the W1VD CW transmitter that used with it during the late nineties, but I'm a phone guy now, and I feel compelled to use this RX as part of an SSB rig.  Of course, I could build a standalone SSB TX, but how about a diode switching scheme to make use of the Barebones' filter, the VXO and the BFO in a transceiver?

Here is my article on the original build of this receiver: http://www.gadgeteer.us/HBHOME.HTM

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

Sunday, March 17, 2013

A Beautiful Workshop in Scotland



A nasty Coronal Mass Ejection hit our magnetic field at around 0600 UTC today.  The HF bands are now in poor shape.  What better time to visit a really impressive workshop in Scotland? 

Ian has an interesting site: http://www.ianjohnston.com/

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

Saturday, March 16, 2013

Vanguard!


Wow, Vanguard even looks like a QRPp satellite. 

I suspected that something was up:  I noticed that Mike Rainey, AA1TJ has recently been crossing pond with a QRPp Germanium rig...  Then Steve "Snort Rosin" Smith clued me in: The next period of  Vanguard QRPp Activity Days begins tomorrow.  "Club 72" has a nice write up, and a nice collection of pictures of the Vanguard rigs that have been built around the world:

http://www.club72.su/vanguard.html

Go Germanium!  Go Vanguard!

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QRP SSB with a New Rig


Kelly, WB0WQS, was trying out a new KX3 that his wife had given him as a present.  The radio gods must like that low-power rig because, in what seems like a deliberate demonstration of the awesome power of QRP phone, Kelly's first QSO was with another QRP operator:  me!  The sun was going down and taking 17 meters with it, but neither of us missed a word.  We talked about SolderSmoke and our mutual friend, Jerry, NR5A -- Kelly had known Jerry when they were teenage hams. Good luck with the new rig Kelly!

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Friday, March 15, 2013

Kludge: Rube-Goldberg Heath-Robinson Ad-Hockery



Wow!  "Ad-hockery... verging on being a crock."  That sounds like my building technique!  I thank Kevin for sending this, but I admit to now being more confused than ever.

Bill:

A snippet from my kluge research.  This was a word I learned from my dad who told me he had heard it first used in the 1930s.  Here is where I find a divergent meaning with the new word kludge which I have often heard pronounced as rhyming with sludge.  I was asked why I pronounced it with the d as silent.  I asked why I should pronounce a letter which was not even in the word.  Thus my introduction to the new word kludge which means something very different than what I had learned from my father.  While a kluge is something clever a kludge is an ad hoc and usually buggy hack. 
I found a little supporting evidence for the etymological timeline. To whit:


Source: The Free On-line Dictionary of Computing (2003-OCT-10)

kluge

   /klooj/, /kluhj/ (From German "klug" /kloog/ - clever
   and Scottish "kludge") 1. A Rube Goldberg (or Heath
   Robinson) device, whether in hardware or software.
   The spelling "kluge" (as opposed to "kludge") was used in
   connection with computers as far back as the mid-1950s and, at
   that time, was used exclusively of *hardware* kluges.
 
   2.  A clever programming trick intended to solve
   a particular nasty case in an expedient, if not clear, manner.
   Often used to repair bugs.  Often involves ad-hockery and
   verges on being a crock.  In fact, the TMRC Dictionary
   defined "kludge" as "a crock that works".
 
   3. Something that works for the wrong reason.

   4. (WPI) A feature that is implemented in a rude manner.
   In 1947, the "New York Folklore Quarterly" reported a classic
   shaggy-dog story "Murgatroyd the Kluge Maker" then current in
   the Armed Forces, in which a "kluge" was a complex and
   puzzling artifact with a trivial function.  Other sources
   report that "kluge" was common Navy slang in the WWII era for
   any piece of electronics that worked well on shore but
   consistently failed at sea.
   However, there is reason to believe this slang use may be a
   decade older.  Several respondents have connected it to the
   brand name of a device called a "Kluge paper feeder" dating
   back at least to 1935, an adjunct to mechanical printing
   presses.  The Kluge feeder was designed before small, cheap
   electric motors and control electronics; it relied on a
   fiendishly complex assortment of cams, belts, and linkages to
   both power and synchronise all its operations from one motive
   driveshaft.  It was accordingly tempermental, subject to
   frequent breakdowns, and devilishly difficult to repair - but
   oh, so clever!  One traditional folk etymology of "klugen"
   makes it the name of a design engineer; in fact, "Kluge" is a
   surname in German, and the designer of the Kluge feeder may
   well have been the man behind this myth.

   TMRC and the MIT hacker culture of the early 1960s seems to
   have developed in a milieu that remembered and still used some
   WWII military slang (see also foobar).  It seems likely that
   "kluge" came to MIT via alumni of the many military
   electronics projects run in Cambridge during the war (many in
   MIT's venerable Building 20, which housed TMRC until the
   building was demolished in 1999).

Source: Jargon File (4.3.1, 29 Jun 2001)

kluge /klooj/ [from the German `klug', clever; poss. related to Polish
'klucz' (a key, a hint, a main point)] 1. n. A Rube Goldberg (or Heath
 Robinson) device, whether in hardware or software. 2. n. A clever 
 programming trick intended to solve a particular nasty case in an 
expedient, if not clear, manner. Often used to repair bugs. Often
  involves ad-hockery and verges on being a crock. 3. n. Something
  that works for the wrong reason. 4. vt. To insert a kluge into a
  program. "I've kluged this routine to get around that weird bug, but
  there's probably a better way." 5. [WPI] n. A feature that is
  implemented in a rude manner. 

  Nowadays this term is often encountered in the variant spelling
  `kludge'. Reports from old farts are consistent that `kluge' was the
  original spelling, reported around computers as far back as the
  mid-1950s and, at that time, used exclusively of _hardware_ kluges. In
  1947, the "New York Folklore Quarterly" reported a classic shaggy-dog
  story `Murgatroyd the Kluge Maker' then current in the Armed Forces, in
  which a `kluge' was a complex and puzzling artifact with a trivial
  function. Other sources report that `kluge' was common Navy slang in the
  WWII era for any piece of electronics that worked well on shore but
  consistently failed at sea.

  However, there is reason to believe this slang use may be a decade
  older. Several respondents have connected it to the brand name of a
  device called a "Kluge paper feeder", an adjunct to mechanical printing
  presses. Legend has it that the Kluge feeder was designed before small,
  cheap electric motors and control electronics; it relied on a fiendishly
  complex assortment of cams, belts, and linkages to both power and
  synchronize all its operations from one motive driveshaft. It was
  accordingly temperamental, subject to frequent breakdowns, and
  devilishly difficult to repair -- but oh, so clever! People who tell
  this story also aver that `Kluge' was the name of a design engineer.

  There is in fact a Brandtjen & Kluge Inc., an old family business that
  manufactures printing equipment - interestingly, their name is
  pronounced /kloo'gee/! Henry Brandtjen, president of the firm, told me
  (ESR, 1994) that his company was co-founded by his father and an
  engineer named Kluge /kloo'gee/, who built and co-designed the original
  Kluge automatic feeder in 1919. Mr. Brandtjen claims, however, that this
  was a _simple_ device (with only four cams); he says he has no idea how
  the myth of its complexity took hold. Other correspondents differ with
  Mr. Brandtjen's history of the device and his allegation that it was a
  simple rather than complex one, but agree that the Kluge automatic
  feeder was the most likely source of the folklore.

  TMRC and the MIT hacker culture of the early '60s seems to have
  developed in a milieu that remembered and still used some WWII military
  slang (see also foobar). It seems likely that `kluge' came to MIT via
  alumni of the many military electronics projects that had been located
  in Cambridge (many in MIT's venerable Building 20, in which TMRC is
  also located) during the war.

 The variant `kludge' was apparently popularized by the Datamation
  article mentioned above; it was titled "How to Design a Kludge"
  (February 1962, pp. 30, 31). This spelling was probably imported from
  Great Britain, where kludge has an independent history (though this
  fact was largely unknown to hackers on either side of the Atlantic
  before a mid-1993 debate in the Usenet group alt.folklore.computers over
  the First and Second Edition versions of this entry; everybody used to
  think kludge was just a mutation of kluge). It now appears that the
  British, having forgotten the etymology of their own `kludge' when
  `kluge' crossed the Atlantic, repaid the U.S. by lobbing the `kludge'
  orthography in the other direction and confusing their American cousins'
  spelling!

  The result of this history is a tangle. Many younger U.S. hackers
  pronounce the word as /klooj/ but spell it, incorrectly for its meaning
  and pronunciation, as `kludge'. (Phonetically, consider huge, refuge,
  centrifuge, and deluge as opposed to sludge, judge, budge, and fudge.

  Whatever its failings in other areas, English spelling is perfectly
  consistent about this distinction.) British hackers mostly learned
  /kluhj/ orally, use it in a restricted negative sense and are at least
  consistent. European hackers have mostly learned the word from written
  American sources and tend to pronounce it /kluhj/ but use the wider
  American meaning!

  Some observers consider this mess appropriate in view of the word's
  meaning. 

I hope this further muddies the definitional waters for you :)

   73,
      Kevin.  KD5ONS




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

Thursday, March 14, 2013

Almost forgot! Happy Pi Day!


3-14   Get it?

And happy birthday Albert Einstein! 

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

Autographed SolderSmoke Books


I have some books left over from Winterfest.   Please let me know if you'd like a signed copy.  Some folks are ordering them as gifts for fellow Knack victims.  I will inscribe them with whatever you'd like me to write (within limits, of course!)

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

Wednesday, March 13, 2013

The Overview Effect


OVERVIEW from Planetary Collective on Vimeo.

Every once in a while, it's a good idea to step back and consider the big picture.

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

Tuesday, March 12, 2013

Fabio's Direct Conversion Receiver



Fabio, IK0IXI, is an electronic wizard from Civitavecchia, near Rome.   Check out his very nice DC receiver. Note that wonderful direct conversion sound.   Very cool that has it atop our beloved SPRAT.   Below you can hear the effectiveness of the audio filter.   Bravo Fabio!



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

Sunday, March 10, 2013

A Ham Radio HackerSpace


Bill -  Enjoyed your conversation regarding seeing the Maker guys at a recent hamfest.  Thought I'd let you know that, at least on a small scale, we've created a ham hacker space in our club by organizing a "Builders Group" as an adjunct to the Williamsburg Amateur Radio Club (WAARC) here in Williamsburg, VA.  I volunteered my QTH as a meeting place and the majority of projects have been either QRP or test equipment related.  Folks select their own project and bring their own tools to use.  These projects have included the Hendricks tri-band QRP transceiver, NorCal FCC-1 frequency counter, N3ZI digital dial, Tuna Tin II transmitter and others.

I corralled two friends in the club to act as "mentors" to assist less experienced builders with soldering and construction.  Once builders complete their projects my workbench upstairs is available to verify correct operation or troubleshooting as required.

Here are a couple of pix of the guys having fun melting solder.

73 - Dino KL0S



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

Saturday, March 9, 2013

Richard's Rip-Van-Winkle Barbados Rig


Dear Bill,

Thank you for taking a few minutes to read my email. I recently found your blog and enjoyed reading the entries.  However, the most interesting and exciting article I discovered was your "Homebrew Radios in the Age of the Internet." The article reminded me of a project started 30 years ago this month and placed in a box in the attic to wait until I could return to it.
Thirty years of health care management work filled the interim.

The project is the 8P6 Hamcation rig by W1FB from QST of June and November 1982!

I searched through the cob webs in the attic and found that all the boards are completed and I even fabricated a case. The original QST's were there too! In response to a (somewhat strong) suggestion from my wife to "get a winter project going", the rig is back on my retirement work bench. Wahoo.

Progress to date has been instructive and fun. The boards are all cleaned, checked, and 95% wired together in the case and working. I attached 2 photo for your pleasure because you wrote specifically about the receiver in some blog posts.

This is where I am scratching my head. As you say in the article, "receivers are tough". I am confused and a bit frustrated about the correct procedure and sequence to correctly align the Barebones superhet. I can already hear stations and the noise level is acceptable. But I am not quite sure how to proceed in peaking up the receiver (hit a plateau?) Any suggestions for a newly retired ham now with the time to get back to the bench?

Thank you very much for your kind comments and interest in my project.

73's
Richard
WB2PEF
Cherry Valley NY


Wow, what a cool resurrection project!   I recognize both the receiver and transmitter boards.   The RX is clearly DeMaw's Barebones Superhet on a FAR Circuit board.  I am listening to one of those AS I TYPE.  Mine was put together by Dale, W4OP, and currently inhales on 17 meters.   The TX board is what became known as the VXO 6 Watter.   It was (I think) designed by W1VD, and appears in the ARRL book "QRP Classics."   This was my first really successful homebrew rig -- I built that transmitter in the Dominican Republic  in 1993.   I still have most of the board, and the 20 meter Barebones RX that I used with it.   Richard's message makes me want to put this old gear back on the air. 

I hope Richard will send us an update on his Barbados revival project.

I'm sure Doug DeMaw would be very pleased to know that his projects are still providing radio amateurs with a lot of fun and inspiration.


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

Wednesday, March 6, 2013

SolderSmoke Podcast #150





SolderSmoke Podcast #150 is now available:

http://soldersmoke.com/soldersmoke150.mp3

March 6, 2013

-- SolderSnow!
-- Winterfest Hamfest report
-- N2CQR WINS ARRL INTERNATIONAL DX DSB CONTEST!!!!
-- Homebrew Direct Conversion RX meets PSK-31 and FLDIGI
-- Kludge Controversy II
-- More Q Killing
-- Fixing up old cassettes
-- Pat Hawker, G3VA, SK
-- Mailbag




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

Tuesday, March 5, 2013

VE7BPO on "Killing Q"

I'm still scratching my head a bit about HOW the resistor prescribed by Edgardo, LU1AR, cured the 250 kHz oscillation problem that was plaguing the JBOT amplifier in my 20 meter DSB rig.   Earlier I'd posted an excerpt from a CQ article in which Doug DeMaw talks about swamping and Q killing.   Last week I got a very thoughtful e-mail from esteemed homebrewer Todd,  VE7BPO.  Here is an excerpt :

Thoughts and Considerations
Let’s discuss squashing low frequency oscillations in a QRP transmitter; say at 200 KHz or so. A low value resistor across the coil (12t -- FT37-43) often works well to stop these.
Oscillations come from the transistor: gain versus frequency isn’t linear, nor is impedance at transistor ports. We’ll often add negative feedback and such to stabilize an amplifier towards unconditional status. In my Tx circuit that oscillated, no feedback was applied. 
 In the case of an inductor wound on a FT37-43 or FT50-43, the Q is already low (say 8- 15 or so). Obviously a resistor in parallel with such a coil is not going to lower Q since Q is already quite low. That R will reduce the inductor impedance and thus may serve to decrease the low frequency gain of the RF amplifier to stop any low frequency oscillations. This might not work so well with a way-high fT transistor where decoupling might be hampered if UHF oscillations are singing. 
Doug DeMaw often referred to the parallel resistor as a Q-killer. If we examine the equations describing parallel, or series resonant circuits -- if the Q of a tank is high enough, we can practically ignore the effect of resistance at resonance. Conversely if we add a resistance and make it high enough, we might even obliterate the resonant frequency or “kill the Q”. Engineers have long placed an R into a parallel-tuned circuit to drop Q and stop oscillations — they refer to it as damping. 1 example might be in old TV sets where a variable resistance was added to peaking coils to prevent a tank from ringing at a frequency determined by the coil L and distributed C. This applies to higher Q inductors and not our FT37-43 inductor. 
Decoupling
Our teacher, Wes, teaches us in EMRFD that coupling often occurs along the DC power supply lines.  Further, he’s taught us to decouple AC by placing high impedance in this path.  Often the impedance is a low-pass filter with series element(s) of a high Z and shunt element(s) with a low Z.  The filter must present a simple short circuit (or perhaps just a resistance) at low frequency so DC flows to the amplifier.    
Final 
Oscillations should likely be identified and treated according their frequency. This topic looks advanced and all RLC networks deserve more attention from us.
Todd, VE7BPO --- Feb 27, 2013
 

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Monday, March 4, 2013

Three Great Videos from Alan W2AEW

Bill:

While not really homebrew, they do deal with QRP and RF.  The first two are walk-throughs of the schematics of two QRP transceivers, and the last is a discussion of how diodes can be used as RF switches.  I thought you'd find them interesting.

MFJ-9340 QRP Cub CW Transceiver kit schematic review:
http://www.youtube.com/watch?v=2QSwXv2RJzw
 
Heathkit HW-9 schematic walk-through:
http://www.youtube.com/watch?v=rPM1vvGorTo

Using diodes as RF switches:
https://www.youtube.com/watch?v=YBNIq_d56sA

73,
Alan
Http://www.youtube.com/w2aew

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

Saturday, March 2, 2013

QRO Problem, and THE KLUGER


Hi Bill,

I've been enjoying your podcasts for a couple of years now and have read both of your books. Please keep up the good work it is much appreciated. In fact, as I can now have both your books and your podcasts on my iPod they are quite literally held close to my heart.

Inspired by your "Kludge Controversy" - enclosed are a couple of photos that I took while on Mount Wellington in Tasmania.


THE POWER OF RADIO

Mount Wellington is a high mountain and is a good launch point for radio waves over the city of Hobart. The visitor lookout has this fantastic warning sign "Electronic disturbances to your vehicle" warning that the transmitter on the mountain can seriously interfere with your car and it may not start, the doors may not open, and the immobiliser may permanently immobilise it. The advice is "A metallic sunshade may reflect radio waves away from the vehicle" and allow you to start it. I'm sure your QRP rigs need no such dire warnings!



WHAT WERE THEY THINKING

And in the very same car park I see this car called a Kluger. In what flavour of English is that a good idea? I know the Brits and Yanks differ over a few phrases but I've never before come across an Oz word that means the exact opposite.

Thanks again for all your many inspiring "broadcasts", and may the Magic Smoke (
http://en.wikipedia.org/wiki/Magic_smoke) always stay where it should!


Steven
G6VRD



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