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Monday, August 31, 2015

"The Soul of a New Machine"



 
We talk a lot about putting soul in our new machines.  The phrase comes from a book by Tracy Kidder.   Ira Flatow of NPR's Science Friday recently took a new look at this book.  There are TWO recordings in this link.  Both are worth listening to.  The second is an interview with the author, conducted at Google HQ in New York City.  Woz chimes in. 


At about 6:43 in the second interview, Ira Flatow and Tracy Kidder get into a little argument about how to pronounce the word "kludge."  I'm with Ira -- the fact that he pronounces it this way makes me think that we are using a New York, or at least and East Coast pronunciation. 

I am a big fan of Tracy Kidder.  His "Mountains Beyond Mountains"  is about Dr. Paul Farmer, a heroic physician who has dedicated his life to treating the poor people of Haiti.  "My Detachment" is about Kidder's stint as an army officer in Vietnam.   Kidder and his editor wrote a nice book about the crafts of writing and editing: "Good Prose."  "Strength in What Remains" is about the genocide in Burundi. 

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

Awesome Kits from Austin Texas




If this is the kind of great stuff that results, then I agree with the bumper sticker:

KEEP AUSTIN WEIRD!

Scroll down to kit #25 for more details on the device pictured above.

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, August 29, 2015

Adam Savage (Myth Busters) Interviews Andy Weir (Author of "The Martian")



I liked this interview a lot, and I am sure SolderSmoke listeners will like it too.
Weir admits to NOT having the Knack, but Mark Watney clearly does have it.

Also, check this out: http://www.cannonade.net/mars.php#map

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

Friday, August 28, 2015

Knack Movie and Book -- SolderSmoke on Mars -- "The Martian"



I realize I'm very late in reading this book.  Billy read it last winter.  The movie is already coming out.  I guess I didn't see the Knack element in this story until I saw the movie trailer.  Wow.  This is a book and movie for us.    Dude is stranded on Mars and has to fix the radio  (with Hendrix playing in the background).  I'm reading the book now (appropriately, on my I-phone).  I find myself thinking about the Elser-Mathes Cup.   

More on the book here: https://en.wikipedia.org/wiki/The_Martian_(Weir_novel)

From the Wiki article:
Andy Weir, the son of a particle physicist, has a background in computer science. He began writing the book in 2009, researching related material so that it would be as realistic as possible and based on existing technology.[4] Weir studied orbital mechanics, astronomy, and the history of manned spaceflight.[6] He said he knows the exact date of each day in the book.[7]
Having been rebuffed by literary agents when trying to get prior books published, Weir decided to put the book online in serial format one chapter at a time for free at his website.[4] At the request of fans, he made an Amazon Kindle version available at 99 cents (the minimum he could set the price).[4] The Kindle edition rose to the top of Amazon's list of best-selling science-fiction titles, where it sold 35,000 copies in three months, more than had been previously downloaded free.[4][7] This garnered the attention of publishers: Podium Publishing, an audiobook publisher, signed for the audiobook rights in January 2013. Weir sold the print rights to Crown in March 2013 for over a hundred thousand dollars.[4]
The book debuted on the New York Times Best Seller list on March 2, 2014 in the hardcover fiction category at twelfth position.[



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, August 26, 2015

Farhan's Secret Project: The SPECAN (Extremely Cool) (video)



I had been sworn to secrecy for so long,  I thought I was going to burst.  I almost hinted at this in the last podcast.  But I didn't.  I kept the secret.  But now Farhan has made public his latest creation: 

http://hfsignals.blogspot.in/p/specan-reboot-of-w7zoi.html

This is really great.  I want to build one.  I have to build one.  I NEED one of these.

Great work Farhan.  Thanks for bringing the ham community another amazing piece of gear.

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

SPECIAL 10th ANNIVERSARY OFFER ON SolderSmoke BOOK FREE DOWNLOAD




On the occasion of the tenth anniversary of the SolderSmoke podcast, I have reduced the price of the book "SolderSmoke -- Global Adventures in Wireless Electronics."  I've taken the price as low as Amazon and Lulu will allow.  

Here are the new prices. (These prices are temporary.)

FREE E-BOOK DOWNLOAD FROM LULU:  http://www.lulu.com/shop/bill-meara/soldersmoke-global-adventures-in-wireless-electronics/ebook/product-20740433.html


Amazon Print version:  $5.54:  https://www.createspace.com/5109055

LULU Print versions:  $4.45      http://www.lulu.com/spotlight/soldersmoke

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, August 24, 2015

Unfazed! Fight HISS-teria! Give the Si5351 a Chance.

 
Thanks to all who have contributed to our discussion of phase noise and the Si5351 chip.  Let me throw out some ideas -- some technical, others philosophical.

1)  We may be worrying about this too much.   In all of the homebrew or kit rigs we've built over the years, I never recall much concern about the phase noise specs of the LC or crystal oscillator circuit that we were using. What were the phase noise stats on a Heath VF-1? How about the phase noise stats for the little Hartley oscillator in those DC receivers we made?  No one even checked. Our rigs usually worked just fine.  We would have noticed if they were extremely noisy, but if they were good enough, we left well enough alone.  It doesn't really make much sense for us to now be suddenly very concerned about the phase noise stats of the various DDS and PLL chips that are replacing those LC and crystal circuits, especially when the measurements show that they are usually in the same range as our old familiar oscillators.   

2) The perfect can be the enemy of the good, and the "good enough."  We have a long tradition in ham radio of tolerating less-than-perfect or less-than-optimum parts.  Remember, the NE-602 has some shortcomings, but we use it. We use it a lot.  The IRF-510 wasn't even designed to be an RF amplifiers, but we have pressed it into service for our PAs.

3) We should be willing to give a new part a try, and we should be pleased if it proves useful.  We should be wary of untested claims re the unsuitability of a component.  We have to avoid the "works in practice, but not in theory" situation.   If something works well, doesn't create additional QRM,  is inexpensive, and fosters experimentation and homebrewing, we should be happy about being able to use it.  

4) All electronic components -- not just the Si5351! --  produce noise.  Resistors produce noise.  Look at this:
" We can infer... that if we install phase-quiet oscillators in transmitter and receiver, we ought to be able to tune our receiver to a frequency closely adjacent to a very strong signal from the transmitter without encountering anything like phase-noise hiss. Yet, after an exhaustive phase-noise cleanup at transmitting and receiving sites, we test our communication system only to discover that the transmitter still emits broadband hiss! The culprit is transmitted amplifier noise. Just about every modern transmitter or transceiver consists of a high-gain, linear amplifier strip that amplifies the low-level output of oscillators, mixers and phase-locked loops to hundreds of watts or a few kilowatts. Because amplifier circuitry is not perfectly quiet, the output of the transmitter contains noise (hiss) in addition to the amplified signal. Transmitted along with the desired signal, this hiss can degrade the noise floor of nearby receivers-just as transmitted phase noise can. Where does amplifier noise come from? Thermal noise, for one thing. Electronic components operated at temperatures greater than absolute zero generate random electrical noise. This noise is broadband in nature. Greatly amplified in an audio amplifier-or greatly amplified in a radio transmitter, transmitted as broadband radio noise, received and converted to audio-it sounds like hiss. Random variations in electron flow within active amplifier components (transistors and vacuum tubes) are another source of amplifier noise. Transmitted as broadband radio noise, received and converted to audio, it also sounds like hiss." Source: http://www.robkalmeijer.nl/techniek/electronica/radiotechniek/hambladen/qst/1988/03/page14/index.html

5) It seems that whenever a new technology or part comes along there will be those who issue dire warnings about how we can't or shouldn't use it.   When transistors came along, there were those who said that hams shouldn't homebrew with them because -- it was argued -- without spectrum analyzers we couldn't possibly come up with spectrally pure signals. 

6)  We have to be careful lest this obsession with perfection and extremely high tech standards be used as a rationale for not homebrewing, or (much worse) as an argument against homebrew rigs on the ham bands.   There is a bit of this going around.   Get on 40 meters with rig that drifts a bit or that is not "on frequency" to within 10 Hz and you will find out what I mean. 

7)  The Si5351 is a good part for our purposes. It does something new and VERY useful for us:   It can put out BOTH our VFO and BFO frequencies.   It makes it much easier for us to change bands and-or switch between USB and LSB.   Its phase noise figures are fine.  LA3PNA (citing measurements by KE5FX) notes: "The phase noise of the Si5351 is around -130dBc/Hz at 10KHz. This is quite decent, If compared to a Hartley or Collpits you would see little or no difference. Some of my measurements of published free running oscilators show phase noise in the -110dBc/Hz range!" 

Fig 5

-130 dBc/Hz at 10 kHz puts this part on the "good" curve of this chart. From (http://www.robkalmeijer.nl/techniek/electronica/radiotechniek/hambladen/qst/1988/03/page14/index.html

We should give this little chip a chance!   Give it a try! 

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, August 22, 2015

SolderSmoke Podcast #179 SPECIAL TENTH ANNIVERSARY EDITION




SolderSmoke Podcast #179 is available:

22 August 2015


YESTERDAY MARKED 10 YEARS OF THE SOLDERSMOKE PODCAST
-- A clip: The first minutes of SolderSmoke #1
-- A trip down SolderSmoke memory lane.
-- The SolderSmoke lexicon -- words and phrases we use (a lot).

BENCH REPORT
-- Pete's antenna project.
-- Pete's new Blog:   http://n6qw.blogspot.com
-- Bill's big amplifier problem fixed thanks to Allison KB1GMX.
-- Six digit freq readout with an Altoids case.

THE Si5351 PHASE NOISE CONTROVERSY
-- ALL oscillators make noise.
-- Keeping things in perspective:  It is 100 db down!
-- Observations and tests from LA3PNA, NT7S, and K0WFS:

-- Try it, you'll like it!  The benefits trying things on real rigs.

NEWS
Interviews on "QSO TODAY" with Eric 4Z1UG.
Horrible band conditions.
Looking at Saturn with telescope.

MAILBAG
Another recruit for the CBLA:  Paul KA5WPL.
Ron G4GXO on Bell-Thorn and Eden9 SSB rigs.
Rupert G6HVY on Kon Tiki radio and Mr. Spock.  
Mikele's Croation BITX rigs.
Dean AC9JQ's TIA.
Bryan KV4ZS will build an LBS receiver.
Dave Anderson give Pete good antenna advice.
Steve Smith moves in from the garage.

Pete has built  12 SSB transceivers.  Intervention time? 

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

Friday, August 21, 2015

Going through a phase (on phase noise)

There seems to be a bit of hysteria on the alleged phase noise problems of the Si5351 chip.  The library yields some words of wisdom that help keep things in perspective:

ARRL Handbook (2002) page 14.5: "You would be excused for thinking that phase noise is a recent discovery, but all oscillators have always produced it."

Experimental Methods in RF Design page 4.12 "At first glance, phase noise sounds like a esoteric detail that probably has little impact on practical communications.  This is generally true."  (EMRFD does, however, go on to discuss the problems that arise on both receive and transmit from EXCESSIVE phase noise.)

Our old (young!) friend Thomas LA3PNA e-mailed on this subject noting that the Si5351 chip produces less phase noise than many Hartley or Collpits oscillator designs.   He provides a link to measurements (far better than mine!) of the noise from the Si5351:

http://nt7s.com/2014/11/si5351a-investigations-part-7/

NT7S puts it this way:

I believe that the plots speak for themselves fairly well. If you compare these results to the receivers in the Sherwood Engineering receiver table, I think you'll see that the Si5351 acquits itself quite nicely for such an inexpensive part. Personally, I think the Si5351 is eminently usable for many receiver applications, except perhaps the most high-performance. Certainly for the price, it's going to be extremely hard to beat. I hope this motivates those sitting on the fence to decide if the Si5351 will meet their needs.

Be careful in evaluating statements saying that the Si5351 phase noise is 3-6 db worse than an Si570.  This makes it sound like there is a LOT of noise coming out!  But again, it is important to keep things in perspective:  The noise from one chip might be -156 dbc/Hz while the "worse" chip might be -150 dbc/Hz.  That's still not enough noise to make a lot of noise about.  

The ARRL handbook recommended a very simple check for excessive phase noise:  Set up a very strong signal in the band of your receiver.  Then slowly tune to the signal, listening carefully for any build-up in noise as you approach the signal.  I did this, and I didn't hear any.  As for transmit, well,  as Pete points out, I think the spectrum police on 40 meters would let us know if our signals were broad or noisy!  The ARRL Handbook notes that in a transmitter, "This radiated noise exists in the same proportion to the transmitter power as the phase noise is to the oscillator power..."


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, August 20, 2015

Si5351 Phase Noise? A Tale of 3 Oscillators

Si5351 at 16 MHz
 
There is still a lot of talk about the supposedly horrible phase noise of the Si5351 chip. In a recent episode of a popular (and very good!) podcast about homebrewing, the podcasters talked about this in the context of some megawatt AM shortwave broadcast stations that had oscillator phase noise problems and were wiping out large portions of the HF spectrum.   I don't think those stations were running Si5351s, but the listener was left with the impression that these handy little chips are very noisy with lots of spurs and will inevitably produce horrible dirty, spectrally impure signals. 
 
This has not been our experience.   Following Pete's lead, several of us are using the Si5351 to generate both VFO and BFO signals in our transceivers, with good results. The receivers sound very good and we have not heard complaints of "broad" or "noisy" transmitted signals.
 
I decided to dig into this a bit.  This was also an excuse for me to use the FFT and screen capture features on my Rigol 'scope.  
 
I now have THREE BITX transceivers in the shack.   My BITX17 uses a VXO at round 23 MHz (IF at 5 MHz)/  My BITX20 uses a classic LC VFO running around 3.5 MHz (IF at 11 MHz).  Finally, my BITX40 (DIGI-TIA) uses the dreaded and much reviled Si5351 running at around 16 MHz (IF at 9 MHz).   I thought that these three rigs would provide a good opportunity to test the scurrilous claims about the Si5351.   
 
As a simple first test, I put my Rigol scope in FFT mode and just put the probe at the VFO Mixer's LO input.  The screenshot above is the FFT for the Si5351.  It looks pretty clean to me.  The 'scope is looking at 15 Mhz above and below the VFO signal.    
 


VFO at 3.5 MHz
 
Next I measured the output of the BITX20 VFO at the same point (input to the VFO mixer).  (I had to change the vertical range, but the horizontal was unchanged.)  Here you can see the second harmonic (just because at this low freq it is within the freq range setting of the 'scope).  It doesn't look much different than the Si5351.   


VXO at 23 MHz
 
Finally, here is the BITX17 VXO at 23 MHz, again at the input to the VFO mixer.   It looks remarkably similar to the Si5351, don't you think? 
 
More on this to come.  The ARRL Handbook (2002) has a good discussion on phase noise. I am digging into this and hope to do some more tests.   For now, I think we should reserve judgment on the utility (for us) of the Si5351.  


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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