The Last Roman Rig: New WSPR DSB Transceiver

They are coming to pack up my soldering iron next week, so I'm afraid this will be my last Roman creation. You can see the W3PM Colpitts oscillator in the center. The KA7EXM AF amp is in the lower left. The Softrock-based Manhattanized PA is in the upper right. To the right of the oscillator is a classic W1FB two diode balanced modulator. You see three big green relays. The top one switches the antenna and 12 volts during T/R switching. The middle one switches the audio amp input, the bottom one switches the audio amp output. (I use the same AF amp for receive and transmit, just switching around the input and output.)

It works fine and has sent and received WSPR sigs. I think it will also do PSK-31 with the FLDIGI program. I could use a one more stage of RF amplification between the balanced modulator and the PA driver amp. Also, the AF impedance match between the KA7EXM amp and the balanced modulator nees work: Roger's circuit was deisgned to drive high impedance phones. That balanced modulator circuit has about 50 ohms at each port. Ideas?

I was thinking of calling it the Achilles. But I think I will go with "L'Aquilone" (The Kite").

Above Board: Manhattan-izing an SMT kit

A while back, Tony Parks very kindly sent me one of his wonderful Softrock RXTX V6.3 Software Defined Radio kits. I took a shot at it, but it turns out that I'm not very good with surface mount construction using small parts. I've gotten very used to the Manhattan style. Still, I did manage to build one of the Power Amplifier modules, and I put it to good use in a DSB WSPR transceiver I've been building (see above) . It worked great. For a while... Then it released some smoke.

I started trouble shooting and it was at this point that I REALLY began to miss good ole' Manhattan (you see, I was born there, and I went to Manhattan College, so I guess this helps explain the affinity). It was difficult to get to components mounted under the board. The whole thing was the size of my thumb... I know, whine, whine, whine... Luddite Geezer-ism strikes again. SPARK FOREVER!

It turns out that the problem was caused by the fact that my shack is just not well suited for this kind of construction. There is a lot of stuff floating around. Conductive stuff. Look closely at the picture below and you will see what I mean. You will see what caused the release of the smoke. Look at the leads on the PA transistor on the left. That's a little bit of stray wire that found its way to the WRONG place. Note the toasted source resistor just below!

Anyway, after a trying to fix this thing, I finally gave up and decided to use the circuit, but in Manhattan form. Everything up top. No SMT. Bigger coil cores. The temperature sensing circuitry went off to the right. The output transformer went off to the left, and the driver stage went down below the kit's board. Here is what it looks like now. Again, it works great.

I want to thank Tony and the Softrock guys for giving me this experience. Their kits are wonderful and are really making a tremendous contribution to the hobby. I strongly recommend them. The instructions are great, much like those of the old Heathkits. But for me, I'll take Manhattan.

SolderSmoke Podcast #125 -- SPECIAL FDIM EDITION

http://soldersmoke.com

Special Four Days In May Edition! 
Opening music: FDIM Bluegrass
Our last (sniff) Italy Travel Report
Snakes and Fireflies in Lazio
G3ROO's Antenna Book
Davinci beacon crosses the pond
WSPR rig repaired
New transceiver built for 30 meter digi
Manhattan-izing an SMT board
Paul Harden's wonderful book
BOB CRANE'S FDIM INTERVIEWS!
"Muntzing" with Michael, G3RJV's "Socketry"
Meeting Andrea IW0HK in Piazza San Cosimato!
MAILBAG: Including mail from Farhan, Roger Hayward and Ade Weiss

OH NO! UVB-76 Goes Off the Air! Duck and Cover!

From Wikipedia:

UVB-76 is the callsign of a shortwave radio station that usually broadcasts on the frequency 4625 kHz (AM full carrier). It's known among radio listeners by the nickname The Buzzer. It features a short, monotonous buzz tone (help·info), repeating at a rate of approximately 25 tones per minute, for 24 hours per day. The station has been observed since around 1982.^[1] On rare occasions, the buzzer signal is interrupted and a voice transmission in Russian takes place. Only three to four such events have been noted. Despite much speculation, the actual purpose of this station remains unknown. On June 5, 2010, UVB-76 stopped transmission suddenly, the first time there is no signal received from UVB-76 since 1982. ^[2]

http://en.wikipedia.org/wiki/UVB-76

The Amateur Scientist, Trivial Motors, Influential Books...

I got a nice e-mail from Keith, VE3TZF, that got me thinking about "The Amateur Scientist" by C.L. Strong. The Wiki article on this book is very interesting:
http://en.wikipedia.org/wiki/The_Amateur_Scientist
Check out the part about Forrest Mims.

Here's Keith's e-mail:

----
Hello again Bill,

In your podcast you frequently make reference to the book, The Amateur Scientist.

This got me thinking back to what REALLY got me started along the path of building stuff for fun.

There were three books I remember reading over and over, even though at the time I had a very hard time really understanding what was on all of those pages. Those books were:

1. 'Codes, Ciphers, and Secret Writing', by Martin Gardner (unfortunately, he recently passed away).
2. Some type of 'build yourself a science laboratory' book.
3. Some type of 'build electric motors' book.

I explicitly remember that one of the tasks in the 'science laboratory' book was to take a burnt out light bulb, etch around the neck, break it off, and turn it into a flask. The flask was supposed to sit on a stand that you already made out of wire (a coat hanger?). I've been trying all sorts keyword searches in Google to fine the name of the book. I'm sure I would recognize it if I saw it. Is this 'The Amateur Scientist'? The closest I have gotten is "Build-it-yourself science laboratory: work like a scientist: build your own equipment, make real findings" by the Oregon Museum of Science and Industry. I'm still looking...

On the other hand, when you described the trivial electric motor, something twigged in my memory. I've built one of those! Many of those in fact! Decades ago! The 'electric motor' book made reference to 3 basic designs. They were called the 'mini', the 'midi', and the 'maxi'. The 'mini' motor was in fact the trivial electric motor. The 'midi' motor used fixed magnets on the armature, and the 'maxi' motor used electromagnets only. I remember salvaging an old wooden pencil box, and stealing some of my mom's knitting needles, to build the 'maxi' motor. I used a 6 volt lantern battery to power it. It worked extremely well, but got incredibly hot! And the sparks! I had not yet learned about volts, amps, and watts. Also at the time I was too young to get the mini/midi/maxi references to womens' skirts.

After a little searching with Google, I hit the jackpot:

* "How to make and use electric motors", Al G. Renner - 1974
* Text and diagrams give instructions for building the mini, midi, and maxi motors and for performing various experiments.

Now I just have to find a copy.

I'm currently spending a lot of time with my nephew, building blinking LED circuits, buzzers, motors, and listening to Morse code. He's really getting into it, and I KNOW that this is important.

I just wanted you to know that your podcast (and excellent book) have far reaching impacts that you may have never intended.

-Keith Robert Murray VE3 TZF

YouTube meets QRSS

They seem like two very different technologies, right? They are certainly at opposite ends of the speed spectrum. But David, EA1FAQ, has made innovative use of YouTube video to present -- in a very useful form -- the signals received by his QRSS grabber over a three day period. This kind of system brings to to visual QRSS a bit of the retrivabililty that makes WSPR so useful and interesting.

David's test period happened to include the time that I was out at our country place with my 3 mW QRSS beacon. Back in Rome I could indeed see my sigs in David's video. He was kind enough to follow up with the actual shanpshot of my signal crossing the Med:

G3ROO's AMAZING Antenna Book

A few years back Ian Keyser, G3ROO, put together a really wonderful antenna book. It is very "down to earth," very practical, very useful for hams seeking to succeed with homebrew antennas. The book was edited by another great person from G-QRP Club -- Tony Fishpool, G4WIF. It has been out of print, but Ian has just made it available through Lulu.com.

Lulu is the printer who also handles my book: "SolderSmoke -- Global Adventures in Wireless Electronics." This means that you can order both books at the same time, perhaps saving on shipping costs. (But remember, for U.S., buyers shipping is free all summer long. ) And there is a 10 percent off sale for all buyers during the month of May (Coupon Code: FLOWERS).

Check out Ian's book here:
http://www.lulu.com/product/paperback/practical-and-tested-aerial-systems/10904725

For more info on the SolderSmoke book, go here:
http://soldersmoke.com/book.htm

Spotting the X-37B Mystery Space Plane

I thought it was kind of cool that the amateur satellite spotting community has been able to locate and determine the orbit of the X-37B. Heavens Above will tell you where and when to look for it. Space Weather has some nice images and videos. It is all a bit reminiscent of The Kettering Group. Go Space Sleuths!

Special on Book: 20% off TODAY only

Andrew, G4CWX, reminded me that the folks at Lulu are having a 20% off sale. Today only. So you can save a lot on SolderSmoke -- The Book. The coupon code is THANKS305.
U.S. buyers might be better off using the free shipping option, but this 20 percent sale will definitely be a good deal for everyone else. http://soldersmoke.com/book.htm

Portuguese Knack: Balloon Launch May 30

I don't think they are radio amateurs, but these guys seem to have The Knack. That's an edge-of-space balloon payload they built. They plan to launch on May 31. You will be able to follow the event live, on-line. They have a very interesting web site: http://spacebits.eu/

DaVinci Milliwatt Beacon Crosses the Pond

We were out in the country this weekend and I brought along the little DaVinci 10 milliwatt QRSS beacon. I was hoping that it would do better with the big dipole that I have out there (vs. the sub-optimal end-fed wire I use here in Rome). Success! Bill, W4HBK, saw the above image on his screen in Pensacola, Florida on Saturday evening. My signal is the little bumpy line just below the Morse signal. Joachim, PA1GSJ, also saw it, and passed along this image:

Better than EE text books! With Free Shipping and 10 % off

I was feeling kind of bad about the fact that while free shipping for the book is available for readers in the U.S., people from other countries are not eligible. But Lulu came through! During May readers everywhere can get 10 percent off by using the coupon code FLOWERS. Lulu won't let you combine free shipping AND the 10 percent off; U.S. customers are probably better off sticking with the free shipping. Customers from other countries can use the 10% discount during May.

Steve, KC2VNI, sent in some nice comments on the book:
---------------------------

I am an electrical engineer and I will say that the way Bill explains things is far, far, better than what I've seen in most books dealing with either communications theory or with communications electronics.

Not to go on a rant, but the college level electrical engineering text books are very poorly thought out and are really not written for the beginner (even an undergraduate electrical engineering student) who does not share the author's years of insight.

I would recommend that people who read the book should post comments about it where hams will find it. I posted comments on E-Ham. I will probably post to Ham Radio nation.

Several tweaks to the book (with the understanding that my comments are NOT meant as a slam on the book nor am I an electronics expert):

1) Give me a more detailed troubleshooting methodology- The literature associated with testing and troubleshooting is very,very limited.
A flow chart or diagram of some sort would be very helpful. I get the impression that Bill's efforts in this area were "cut and try" because of his obvious enthusiasm. Having said this, the beginning home-brewer has NO IDEA as to what he needs in the way of test equipment, what he should look for when testing a circuit, what the wave forms should look like, etc. (Note from Bill: A detailed discussion on troubleshooting methodology would be very helpful to students taking electrical engineering online.)

2)Very little discussions about the more mundane things like power supplies, connectors and the like. These trivial items can cause you hours of frustration if you don't think this through. If you want to string things together on a bench, I suppose it does not make difference. However, if you want to operate say QRP mobile in the woods then you need something that has a little bit of thought.

3) Very little discussion about heat sinks and thermal management- This is one of the most neglected areas for most people in electronics (and not just the homebrewer of radio equipment). Here, I recommend the ASME text "Hot Air Rises and Heat Sinks: Everything You Know About Cooling Electronics is Wrong". When I read the discussion about a transistor running hot and extra heat sink compound being applied in the book, I wanted to scream!

One other thing-is there any way I can get an autographed copy of the text?

Thank You very much for this very fun book

73

Steve KC2VNI