A Different Kind of Workshop

Sometimes it is good to take a break from the electronics and look at how people are making other things.  I've been working on the heat sink for a 140 watt solid state amplifier, so this fellow's comments about working with metal kind of resonated with me.   


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

SW Echo Theory Confirmed By a BBC Engineer

BBC Relay Station Singapore

Hi Bill,

I heard your description of the echo on your podcast and before listening I knew the cause - but I think you know that now!

Yes, it's from two separate transmitters, and quite common, though not usually noticed.

It has nothing to do with path length differences - the longest round-the-world echo via the ionosphere is only about 0.15 seconds - so anything more has a different cause.

It's from the audio feed to the transmitter. Your regen receiver picked up two transmitters on different frequencies. It was very noticeable before transmitters used digital land-line feeds, just analogue and satellite.

On a BBC SW frequency (forget the which one now) one tx was in UK and the other in Singapore, on the same frequency with the same programme to completely different service areas. When propagation was right and listening in Europe, the UK signal fed by analogue audio from Bush House came first and the Singapore tx came with two geostationary satellite delays later, plus the tiny bit of UK-Singapore ionospheric path difference.

Now it's worse because there are all sorts of digital delays via land-line and satellite, although using the same frequency for the same service in not common.

In the UK Absolute Radio on AM medium-wave has multiple transmitters (mostly 1215 kHz and 1197 kHz) on the same frequency which are audible at night. If you listen carefully you can often hear multiple (up to FOUR!) echoes from different transmitters all being fed by different internet feeds/satellite links with varying delays. 

As an ex-BBC engineer, I can tell you that in the old days not only were these AM medium-wave group stations all synched to within 0.05Hz, but the phase of the modulation was adjusted so all tramsitters were modulating in phase! Now the commercial boys have taken over most of these syched groups, not only are the frequencies all over the place, but the modulation isn't even time delayed to match, let alone synchronized! Some even put diferent commercials in the breaks so if you're geographically between stations you get a complete, unlistenable-to mess. Apparently these days that's ok.

Why did we bother...?

Anyway, I hope this adds to and confirms your findings.

73,

Ian Liston-Smith, G4JQT

(A grumpy old retired BBC Engineer)

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

Swedish Mighty Mite

A thing of beauty!  Check out the key! 

What a great diagram.  Schematic included! 

http://www.sm7ucz.se/MMM/MMM.htm

Remnants of mine

Steve "Snort Rosin" Smith's 

More on all this: 

http://soldersmoke.blogspot.com/search?q=michigan+mighty+Mite

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

Thomas KK6AHT's Pacificon Minima Presentation: Noodling! And Maxima Inspiration!

Wow, the Minima presentation by Thomas at Pacificon was really great.   I think he had exactly the right tone and tech level for the digitally-savvy California audience.  His very open description of the ups and downs of his Minima build will surely lure in some new builders, and will at the same time prepare them for the travails ahead!  Great stuff.  I like the mention of Pete's "noodling."  Thomas obviously gets it.  And he obviously has THE KNACK.  Thanks Thomas!  

Thomas has posted his slides and (MOST IMPORTANT) the audio of his presentation.  Just click on the BIG ORANGE play arrow below the slides.  You folks will love this: 

http://www.sarfata.org/2014/10/Minima-Presentation-at-Pacificon/

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

Drake-uino! Arduino DDS puts Drake 2B on 12 meter band!

After using the Arduino DDS as a crystal substitute with my 1982 Barebones Superhet recevier (scroll down), I moved back two more decades and used the DDS as a crystal substitute to put my (early '60s) Drake 2B on the 12 meter band.    This was a hack in which I actually used a hack saw -- I used it to cut open the container holding a crystal so that I could make a socket that would carry the signal from the Arduino DDS into the Drake 2B. 

This video is a bit repetitive, but it stated out at two different videos.  I just put them together.  The last part shows the actual crystal socket hack. 

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

Arduino DDS meets Barebones Superhet (Video)

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

Pete's 17 Meter VXO Transceiver (Video)

Pete:  

I like it!  You and I may be the only people in the world with that kind of VXO range control switch on the front panel!

 

I checked my VXO.   I run it at around 23 MHz.  I use two single crystals, also switched by a relay. 

The 23.144 rock tunes from 23.127 to 23.151    24 kHz

The 23.166 rock goes from  23.144 to 23.168    24 kHz

 So I could have had 48 kHz were it not for the overlap.  As it is, I get 41 kHz.  Not bad.

 

The reason I went with this LO freq was that I had these crystals from the Dale Parfitt/Doug DeMaw Barebones Barbados Receiver.  DeMaw had used color burst rocks for a 3.579 MHz IF, but Dale shifted up to 5 MHz. I could occasionally hear WWV!  (But with the 3.579 I heard W1AW in the IF!)

 

73

 

Bill  

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

Homebrew Double Balanced Mixers by Pete Juiano (Part II) Video

Another great video from Pete.  I like the unbalancing mod -- I hate having to whistle into the mic!

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

Hacker with The Knack Does Well, Working for JPL

Wow.  This guy has a really inspirational Knack story.  He welded (with coat hangers!) a sidecar onto his bike when he was a kid.  He majored in Physics and Theater.  He did all kinds of hardware and software hacks. He plays a Theravin in a band.   He now flies spacecraft for the Jet Propulsion Laboratory. 

And Congratulations to Peter Parker, VK3YE, for having one of his ingenious hacks picked up by Hackaday:
http://hackaday.com/2014/10/06/dusty-junk-bin-downconverter-receives-fm-on-an-am-radio/

Thanks Hackaday! And Happy Tenth Birthday to You!  

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

Edison is Off The Grid (and has been for 24 years!)

I talked to him last night on 17 meters.  He's a nice fellow.  When your first name is Edison, that's an indication that you might have THE KNACK.   

From his QRZ page: 

Ready for this?
My wife and I have lived off-the-grid for more than 24 years. Solar and wind are our main power sources on our mountain, although, we did finally add a generator to our available power sources, for those long days of "NO SUN" in Winter.  Check out the view from my home at this site:  http://mycampage.com/rosevalleycam  and also look at the other links on the page.  You might find something you like....
I've been a ham since 1967.  Started as a Novice near Sacramento, California, where I was born. But WN6FIC soon became WA6FIC, which I remained until the late 90's, when I became N7GCW.
I am a musician. Along with my wife, and Blaine Lindgren, our fiddle player, we comprise the band called "Half-way There". Click on my campage link to see more about me, and you will find all of my other links there too.  I am also a photographer. I shoot it all, but REALLY enjoy taking pictures of scenery, and live bands at Concerts we go to. I am also very fond of Sunrises, and Sunsets, and they ARE beautiful here.....

Also, check out his TREK page: 
http://n7gcwtrek.weebly.com/index.html

And I liked his description of his county in Washington state: 
"...I absolutely LOVE my world, here in our little valley.  Our friends are like family here.  People smile and wave...and mean it!  We heat exclusively with wood we cut from dead trees on our land, use propane for cooking and refrigeration, and we use solar and wind for most of our power needs, only supplemented by a generator in those long days of no-sun in Winter.  It's like living in a time warp, here in our neck-of-the-woods....  Do you know that there isn't a traffic signal in the entire county?" 
See: http://edisonshomesite.weebly.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

Pete's Homebrew Double Balanced Mixer Video (Part 1)

Another great video from the famed Italian Director Giovanni Manzoni!  Bravo Giovanni! 

Pete's discussion of double balanced mixers and the associated toroids has made me feel uneasy about my efforts in this area.  I wonder if my diodes were completely matched.  And I KNOW that my toroids are not as well done as Pete's.  

I recently put an SBL-1 into my old, long-evolving 20 meter ceramic resonator DSB rig. Careful with those nice little boxes! A bit too much juice and you can fry the little internal toroids (as I have done!). 

A while back I found in an RSGB Handbook a nice diagram showing how the diode ring mixer does its thing: 


 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

SolderSmoke Podcast 166: Getting Started in Homebrew Radio

SolderSmoke Podcast 166 is available for download: 

http://soldersmoke.com/soldersmoke166.mp3 

Bench Report:  Pete working on Direct Conversion Receivers.  
Bill on his 2B and on 20DSB rig, and an M0XPD/Kanga DDS kit, and a 140 watt amp. 

GETTING STARTED IN HOMEBREW:
Start simple:  Build an oscillator. Make it oscillate!
Gather tools, simple test gear, and books. 
Try to understand what you build. 
Build a direct conversion receiver.  
Don't fear the toroids! 
Be patient.  This is not Plug and Play. 
Build a DSB transceiver. 
Little tips: 
Protect variable caps. 
Use heat sinks. 
Use reverse polarity protection. 
Don't breathe the solder smoke! Ventilate your bench.

China Radio International Mystery Solved.  
Book Recommendation:  "International QRP Collection" by Dobbs and Telenius-Lowe
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

Sines, Squares, Harmonics, 'Scopes, FFTs, and Sounds

Bil Herd of Hackaday did a very nice video on Sine Waves, Square Waves and FFTs.  This is, of course, an important part of understanding how mixers mix.   I look forward to his upcoming video on Direct Digital Synthesis.  

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

Hunting for Sprites

Don't let the comments about "positive lightning" and "gravity wave" cameras turn you off -- in the world of meteorology, these terms seem to make sense (but I had to do some Googling).  The New York Times article on this topic is very interesting: 

http://www.nytimes.com/2014/09/30/science/on-the-hunt-for-a-sprite-on-a-midsummers-night.html?_r=0  

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

Beautiful Pictures of Mars from India's Spacecraft

Congratulations to the Indian Space Research Organization.  They put a spacecraft into Mars orbit on their first attempt, and they are getting back some spectacular images.  

I also like the banner on their web site: 

More info here: 

http://www.isro.org/pslv-c25/Imagegallery/mom-images.aspx

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

Don't miss Thomas and his Minima at Pacificon!

Thanks for the kind words Thomas.  Be sure to have someone do a video of your presentation.

You truly have The Knack -- proof of this is your reaction to your wife's departure for field research in Senegal:  "IT'S SOLDER TIME!"  That's the spirit! 

Too bad about the chickens, but hey, they died for a good cause... 


Dear Bill,

I have been listening to your podcast for about a year now. I think you were right to say that one episode a month is a reasonable limit to avoid listeners getting addicted. At some point in January I was listening to you every morning and every evening in my car, a very serious case of addiction.

This is also the time that Farhan chose to announce the Minima and my wife to go to Senegal for 3 months for a field study (she is doing a PhD in Sociology). I think it took me less than a week to run to the shop, get most of the parts and start melting solder!

In two weeks from today I will present the project and my build at Pacificon. I would really appreciate if you could mention this on your blog because I am sure there are other listeners who will be there and curious for some homebrewing-materials. I hope to delight them!

For your own pleasure there are some pictures and videos on my blog: http://www.sarfata.org/ham/minima/ 

Pacificon Schedule:  http://pacificon.org/ (My talk will be at 10:45 in the Portland room)

My presentation will retrace my journey building the minima. From the first smokes on the crystal filter when I was not even sure how to test it, or what results to look for ; to the amplifier where I am still battling some oscillations (by the way, if you had not talked so much about them, I would never have understood what was going on!).

This project has taught me that radio is a lot less black magic than I thought. It bridged the gap between the maths that I can understand but not really "see" and the sound coming out of the amplifier. It made me realize that once split into stages, a radio is much better understood and testable. Without a doubt, this has been my most ham-enriching experience and I hope to convince more people to build a minima, preferably Manhattan style! 

(In this public setting, I will probably not discuss killing chickens to exorcize my amplifier but I thank you for the tip ...)

I got pulled back from homebrewing by life and work this summer but I kept the last three episodes of Soldersmoke on my phone. They were my safety parachute and I listened to them last week on the way home to give me the extra boost that gets me to melt solder or fix bugs until 3 in the morning on a tuesday. I don't think I will ever be able to express my gratitude for all that I have learnt reading the book and listening to you but I would like to start here: Thank you!

Please keep the podcast going! I have really enjoyed the new format with Pete. 

73,
thomas
kk6aht / f4hdq


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

Let's Build Something! (Video) Part 1

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

Radio China International Echo Mystery SOLVED!

For the past month or so I have been wondering about a strange echo that I've been hearing on the 31 meter transmissions of Radio China International.  I first noticed it on my "Kings Speech" regen receiver.  Then I heard it again on my "Off the Shelf" regen.  

For a while I thought that what I was hearing was a propagation effect:  Perhaps the very strong RCI relay station in Quivican,Cuba was sending north a signal so strong that it was travelling around the earth along the grey line and coming back to me about .133 seconds after the original reception.  

This sounded plausible (and it does happen sometimes).  But there were reasons for skepticism: Why wasn't anyone else hearing this?  Why wasn't the effect showing up on signals from Radio Havana Cuba?  

Pete Juliano had suggested that perhaps I was getting signals from TWO different RCI transmitters.  I had quickly checked the RCI schedule and didn't see them transmitting on the same frequency at the same time from multiple transmitters, so I kind of put that idea aside.  Hey, the round-the-world idea was just more appealing! 

But then I remembered something strange about the echo:  It seemed to disappear when I tuned close to the center frequency of the RCI signal, but then appeared when I tuned off to one side. Hmm.... That was an important clue. 

I've long been wary of regen receivers and for a while suspected that I was dealing with some weird regen effect.  Regen and Echo seem to go together, right?    Well, as it turns out, no.  But I was right about this being an effect of the nature of my receiver... 

Last night I was listening to RCI English service at around 0030 UTC on 9570 kHz.  Nice clear signal.  No echo. 

At 0100 UTC the program changed, and the echo started.  A very strong echo. 

I went to the RCI schedule.  Here I found the answer: 

At 0030 they were transmitting from their relay station in Cerrik, Albania on 9570 kHz. 
At 0010 they switched programs, frequencies and transmitters.  At 0100 Cerrik shut down, but the Quivican, Cuba relay came on on 9580 kHz.   At the same time the RCI transmitter in Kasi Sabagh in far-off exotic Western China, in Xinjiang, fired up on 9535 kHz.  Both transmitters were carrying the RCI English service. 

You see, my little regens are not very selective, and the RCI transmissions are quite strong.  So if I have my receiver tuned to around 9560 kHz, I'll be hearing BOTH the signal from Cuba AND the signal from Xinjiang.  That would explain the echo. 

To try to confirm this, last night I fired up my old Hammarlund HQ-100 receiver to see if I could discern the two different signals.  I could.  And the echo appeared when I tuned BETWEEN the two.  You can hear this in the video above. 

There is one remaining question here:  Is the echo caused by the RADIO path difference between the two transmitters?   Or are we just seeing the effect of the programming being transmitted at slightly different times, perhaps with this delay caused by INTERNET latency?  Anyone know how RCI gets its signals from its Beijing studio to its distant transmitters?   I calculate that the path difference is about 10,000 km.  With c at 300,000 km/second, that would yield an echo of only about .03 seconds.  The echo we are hearing sounds longer than that, so I suspect we are hearing a difference in studio-transmitter transmission time.  What say the SWL RF gurus?

BTW:  I think the same phenomenon may explain the echo on Brother Stair's "Overcomer" signal.  I see that starting at 2200 UTC he is on BOTH 7570 kHz and 7730 kHz from RMI transmitters in Florida.  Perhaps they are not synched up. 

I think this is all very cool.  Think about it:   Here I am, sitting in Virginia in 2014, listening to the Albanian, Cuban, and Xinjiang relay stations of Radio China International on a receiver first built by some guy in England during the 1930s.  And I'm trying to figure out if the echo I hear is caused by the limits imposed by the speed of light and the size of the earth,  or by the time it takes packets to move through sub-oceanic fiber optic cables.   

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

Making Hardware for Mars in a Lab in New York City

I liked this video about building hardware for a Mars mission at a lab in New York City.

http://www.sciencefriday.com/video/08/10/2012/building-for-mars-sometimes-painful-always-glorious.html


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

The Amazing Apollo Board from Carbon Origins

Wow, lots of possibilities 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