In my last post I described my Arduino Keyer Kludge. In that project I didn't use the standard "shield" board that normally sits atop the Arduino board. I had used a shield in an earlier project and I didn't really like it. I prefer to have all the electronics and connections on the top of the board -- this makes for easier experimentation and modification.
Above you can see my "sidecar" technique. I build the circuit on a piece of copper clad board using isolation pads superglued to the copper (aka "Manhattan style"). For the Arduino board, I just superglue a piece of balsa wood to the copper clad board, and attach the Arduino board to the balsa with small wood screws. Electrical connections from the Arduino to the sidecar just go from the Arduino pins to the appropriate points in the sidecar circuit via small-gauge wire.
Ooops -- I got my keyer terminology wrong in this video. The K1EL keyer just needs a "paddle keyer" input, not an iambic keyer. One line is brought to ground for dots, another for dashes. (With an iambic keyer, if you make both contacts at the same time you get a string of alternating dots and dashes.) My homebrew cootie keyer did the job, but I wasn't very proficient, hence the need for this digital kludge. I also got the name of the Arduino guru wrong: he is Massimo Banzi. Mi dispiace Massimo.
Manassas Hamfest Building a Balanced Modulator in LTSpice Peter Parker's Minimalist SDR receiver Alberto I2PHD's SDRadio program My Arduous Arduino Adventure: Sig Generator MAR-1 amplifier chip WSPRing again (the sound of WSPR) Broadening my Barebones Superhet for phone Cliff Stoll on Kludge vs. Kluge FDIM INTERVIEWS: G3RJV on one and done projects, Sodder vs. SoLder, Regens G3VTT plays SolderSmoke for his students NM0S on new Four States PTO rig K0NEB on kit building techniques NH6Z on high performance SDR KK7B on hard rock rigs, modular construction and understanding I2RTF Saluti a tutti! W7EL on EZNEC, Dilbert, and escaping the Cube Farm W1REX on QRP as a creative outlet, Knack to the Max!
SPECIAL THANKS TO SOLDERSMOKE'S DAYTON
Today I bought a copy of "Feynman's Tips on Physics." I wasn't sure about buying it, but this story in Ralph Leighton's foreword convinced me:
"At a lonely border post high on the Himalayan frontier, Ramaswamy Balasubramanian peered through his binoculars at the People's Liberation Army soldiers stationed in Tibet ― who were peering through their scopes back at him. Tensions between India and China had been high for several years since 1962, when the two countries traded shots across their disputed border. The PLA soldiers, knowing they were being watched, taunted Balasubramanian and his fellow Indian soldiers by shaking, defiantly, high in the air their pocket-sized, bright-red copies of Quotations from Chairman Mao ― better known in the West as "Mao's Little Red Book."
Balasubramanian, then a conscript studying physics in his spare time, soon grew tired of these taunts. So one day, he came to his observation post prepared with a suitable rejoinder. As soon as the PLA soldiers started waving Mao's Little Red Book in the air again, he and two fellow Indian soldiers picked up and held aloft the three, big, bright-red volumes of The Feynman Lectures on Physics.
One day I received a letter from Mr. Balasubramanian. His was among the hundreds I have received through the years describing the lasting impact Richard Feynman has had on people's lives. After describing the "red-books" incident on the Sino-Indian Frontier, he wrote, 'Now, twenty years later, whose red books are still being read?' "
Mama mia! That's an antenna! This is the skyhook that the very hip people in yesterday's video (scroll down) are using to send very cool messages to Gliese 526. With a setup like that, they may have a shot at a QSO! More on the antenna here: http://www.jamesburgdish.org/
The project has many features that put it in the traditional SolderSmoke area of interest, especially "the use of a re-furbished radio telescope." But one look at their video (click above) made me think that perhaps these folks are just too cool for a project like this. I somehow can't see ANY of these people using a soldering iron. On the other hand, if WE had videos like this, maybe we'd be able to bring more young people into ham radio! Yea! Why can't we be cool too? How about it, ARRL?
Elisa heroically accompanied me to the Manassas Hamfest on Sunday. We had fun. I thought they had a good turnout of vendors and tailgaters, and it seemed like the sellers of real ham stuff were winning the battle against the encroaching computer people. I saw many interesting old boatanchor radios, including two R-390A receivers, one HT-37, an HW-101 and several other Heathkits.
As for NEW technology, the fellows from the NOVA LABS maker space had a very interesting table, and their web site has a very kind acknowledgement that hams were "the original hackers, who organized build groups and hack labs similar to modern day makerspaces—back before people called themselves “Makers” and long before it was “cool.” They had a 3-D printer that was doing its thing in a very impressive manner. They also had some quadro- and octo-copters built by a group called DC Area Drone User Group. Very cool. Want one.
Inspired by Nick Kennedy, I have included in this post a picture of my purchases from the hamfest. As you can see, I controlled myself. But I couldn't resist the humungous flashlight! I got a bunch of .1 caps (should have bought more!). Got a Bud-box (maybe for an Arduino DDS project?) The little circuit board with the IF cans is interesting. I bought it (1 dollar!) for the 365 pf variable cap, but I later realized that it is probably a complete All-American Five receiver on a single board. I'm not crazy about tubes on PC boards, but this one may have some possibilities. The roll of tape is supposedly coax sealer. I also got a little 35 mm slide viewer, and a 12 volt wall wart.
I wore the "Real Radios Glow in the Dark" T-shirt that Elisa got me (on the recommendation of Rogier). I got more positive comments on that shirt than on any other piece of clothing I've ever owned!
And we saw our first Cicadas of this 17 year cycle.
N3ZI has a very plausible explanation for the low price (about 9 bucks!):
My guess is that this is a liquidation due to a design build error, since they are being sold for a price of about 1/2 the price of the DDS chip alone. The modules are assembled and tested. The design error I noticed is that the wrong output filter is used. These boards use the 9850 running at 125MHz. A 125MHz DDS should have a 50MHz LPF, but it seems that these modules have the 75MHz LPF the chip maker recommends for the AD9851 running at 180MHz. My guess is, someone just copied the wrong filter from the wrong data sheet, and it wasn't caught until they went into production. But for amateur radio applications they work fine up to about 40MHz. You can push them to 50MHz by adding a correcting filter, which is included in my controller PCB, but the output level is low in the 40-50MHz range.
N3ZI continues to offer some really interesting microcontroller products. He has a controller board that allows you to simultaneously control TWO AD9850 boards. This might be exactly what we need when we have a separate receiver and transmitter with different intermediate frequencies: Set up one board with the VFO freq for the receiver and the other for the transmitter with the resulting operating freq displayed on the LCD. Viola! No more "Spot" or "net" and zero-beat by ear! (But I may be one of the last people on the planet still doing this!)
N8ZRY has a very nice video on his recent adventures with the legendary R-390A receiver (want one!) and his homebrew 20 meter SSB transmitter. He manages to essentially put the receiver and transmitter into "transceiver" mode. Very nice. I wonder if he had previously used the old standard "spot" or "net" "zero beat by ear" method? This video has me thinking about ways to bring my many separate receivers and transmitters closer together. The problem is that they all use different IF frequencies (the crystal filters are at different frequencies). But using my Arduino-based DDS VFO, I guess it wouldn't be too difficult to program the thing to generate one VFO freq for transmit, and a different VFO freq on receive, in effect putting the transmitter and receiver on the same frequency.
Both the R-390A and the homebrew transmitter look great.Thanks Greg!
I was getting kind of worried. I hadn't seen any new articles on Alan's excellent web site. But on my last visit I learned that he has moved to Seattle and is going to Maker Faires: http://www.vk2zay.net/article/268
This weekend I put the Arduino/AD9850 Direct Digital Synthesis device into a box this weekend. It is sort of evolving into a general purpose HF signal generator and/or VFO. It is really kind of neat that this little collection of boards can generate RF across that range, with accurate digital readout. Thanks again to Richard Visokey, AD7C, for the circuit and the code. As you can see, my cabinet making skills will never land me a job on the Discovery Channel, but I'm kind of pleased with the box. I picked up the wood panels from a hobby/craft shop.
I left a lot of space in the box. I envision an amplifier taking the output from its current .4 milliwatts up to around 10 milliwatts, followed by step attenuators (pads).
Here is the other end. Of course, I could have just taken the ATMega chip out and avoided putting the whole Arduino board inside the box, but I'll leave that exciting digital adventure for a future project.
I know that "simple" and "homebrew" aren't the words that come to mind when we think of Software Defined Radios, but minimalist guru Peter Parker, VK3YE, reminds us that with little more than an antenna, a diode, a crystal oscillator and a connection to the computer soundcard, you can dive into the world of SDR.
I've been doing this for some time now, but my receiver uses a 40673 dual gate MOSFET and a universal VXO from George Dobbs, G3RJV. I've been running mine with the FLDIGI and JT-65 HF programs. Peter's video alerted me to the charms of SDRadio from Alberto, I2PHD. This is a very nice program. Of course, I'm always happy to add a dash of Italy to my operations. Thanks Peter! Thanks Alberto! Thanks George!
In response to popular demand, "SolderSmoke -- Global Adventures in Wireless Electronics" is now available as an e-book for Amazon's Kindle.
Here's the site:
For the print version:
For shipping from a printer in the U.S. (probably better for N. American buyers) Click here: SolderSmoke USA Version
For shipping from a printer in the UK, Spain, or the USA (probably better for UK and other European buyers)
Click here: SolderSmoke EU Version
The two versions are identical, except for a minor difference in the paper used. That's why the prices are a bit different.
Bill's OTHER Book (Warning: Not About Radio)
Click on the image to learn more
W4HBK's QRSS Grabber: The Amazing Pensacola Snapper (Live!)