Jac (KA1WI) and I spoke on 40 meters on June 29th. I told him about the BITX -- he said he liked the idea of building something and pledged to start melting solder. This week I got this message and video from him. Good going Jac! That was fast! I think we all know who designed the IF amp: Wes W7ZOI. As for the DS/PLL, I recommend you take a look at the Si5351 with an Arduino microcontroller.
I started in July building a receiver with the available parts I had collected over many years. Finally today the receiver is working more or less to my satisfaction. Here is a brief description.
I am using a set of crystall filters from an old Atlas 350XL, 5.595 is the IF frequency and the filters have independent USB and LSB plus CW 500 Hz filter. The radio set is a single conversion type. A DBM at the front end and as product detector. Keeping the BFO signal from leaking is a challenge but I managed by carefully matching the three ports of the DBM used as product detector. Matching the IF filters impedance was another challenge. Following the DBM there is a LNA amplifier using a 2N3866 and I am trying another LNA with a discontinued Siemens BFT66 transistor with a very low noise figure. I have some experience with those and they can be amazingly quite.
The IF amp is a hybrid cascode with three stages and AGC that I found in the internet designed by a well known OM, the design works very well it is easy to make and is very stable despite its nearly 70 dB of wide band gain. The AGC range is close to 100dB . . .
The front end has 6 BPF covering from 1.5 to 30 Mhz all switched by relays. This unit I got from an old German receiver.
The VFO or 1st LO is a DDS unit I had played with years ago. From N3ZI is far from perfection but it does the job when the bands are alive and well. The alternative to the simple DDS are complicated. I wish there were more DDS PLL kits available. It can take a long time to get a full synthesizer satisfactorally working.
The set is made of mechanical parts from a Tektronix main frame instrument, there are many parts of different shapes that can be attached together in a crazy way but certainly very functionally. There is the IF amplifier and the Product Detector BFO enclosed in two brass silver plated boxes, both also recovered from some surplus ages ago. The DDS is one of the sides on the chassis without any shielding.
The IF filters and the front end are going to be attached to the rear of the chassis by just adding brackets etc., you get the idea. I am glad the video is acceptable.
I thought it will interest you know that at age 70 is also possible to roll your own, despite having to check every solder joint since my eye sight is the biggest problem
I have other projects, another receiver with an IF of 9 mHz with SSB and AM filters using another type of high gain IF amp.
Pete Juliano and I were talking on Skype yesterday evening. He was regaling me with tales of the wonders of his new beam antenna. He mentioned that he was working a lot of East Coast stations... Wait a minute, I thought, I'm an East Coast station. And I have a 20 meter rig sitting right in front of me. "Meet me on 14.190 Pete!" It took me a minute or so to get the rig connected to the CCI amplifier and the 20 meter dipole. By the time I got everything fired up, there was a station on the frequency. I thought we'd lost the spot. But no! I realized it was Pete calling me.
This was extremely cool. Pete was using his ZIA rig with the brand new beam. I was on my VFO BITX20. And I was using the CCI amp that Pete had coached me on (he taught me how to tap the holes for the heat sink).
This was the first time I had ever contacted another homebrew SSB station -- and the first time Pete and I had spoken on the air. THE RADIO GODS WANTED THIS ONE TO HAPPEN!
Interested to hear you talking about civility ... My introduction to amateur radio was via a Heathkit GR 64 and Roy, G3PMX. When I finally took my ticket - 1970, and passed, I called him on the phone to tell him - he told me to come on up to his QTH, I did, via an old bike taking about 30 minutes to get up the hill. When I got there, he put me on the mike, the guy the other end was really great, talked about being a part of an international brotherhood and a movement for world peace - just a magical first contact ...
Roy asked me if his call seemed a little odd, it did, it was short, JY1, but I was really slow to cotton on to who I'd just spoken to... What really blows me away to this day was that the King of Jordan sat in his shack and waited for a 16 year old kid to pedal up the hill just to give him a fantastic first contact ... My only regret is that I never got to speak to him again to say "thank you" - when you talk about legacy radios, it isn't the tech that we need to hold on to, though we do, it was what that man did to reach out to a fellow amateur. By all accounts, he was a fantastic guy, he used to sit at Roy's kitchen table drinking coffee and just being one of the guys ... Sadly I was at sea by then hence not meeting him.
Roy knew him because he worked for Marconi & put the antennas on the palace, Hussein just appeared having that Roy was an amateur and they had a long conversation about radio - when he turned to leave, Roy asked his name so that he could stay in touch - Hussein told him to just ask for Hussein the radio guy - never let on that he was King ... Roy said that on several occasions, JY1 travelled to the UK more or less incognito and hired fairly innocuous cars to get about the country simply because he was here as an amateur, not a head of state …
I really do regret that I never got the chance to say “thank you” to him – it was the sort of gesture that I have always thought typifies what you have tried to support and continue, and is indeed carried on by the likes of Joe Taylor who once took the time to respond to an email from me explaining how to set a WSPR system up despite being Nobel Prize winner !! Great example of the spirit of amateur radio transcending all else :-)
Paul Hodges, KA5WPL, didn't have the variable capacitor called for by the Michigan Mighty Mite schematic. So in the true spirit of the International Brotherhood of Electronic Wizards, he rolled his own! He used two empty aluminum cans and some electrical tape. Wow, that's really cool Paul.
You have truly earned you membership in the Color Burst Liberation Army, and for the capacitor I award you the prestigious Brass Figlagee with Bronze Oak Leaf Palm.
This is almost too much. Sensory overload is a real risk here. Go check out AA7EE's amazingly beautiful regen receiver. On his site he has a masterpiece of a write up, along with schematics and build photos. I love the plug-in toroids. Great work Dave. Thanks for sharing this with the homebrew community.
That Drake 2-B is a beautiful thing. Every time I look at an older tube rig I'm reminded of the three dimensionality of these old machines. Solid-state rigs are in Flatland, but tube rigs are in three dimensions.
Alan makes a very cool use of the I-pad in this repair. And I'm jealous of his Hayseed Hamfest Electrolytic (I opted for the multiple caps hanging below the chassis). Excellent management of the solder-sucker by Alan. And I was impressed by the disciplined way he pulls solder from the reel -- he has the reel right next tot he rig and dispenses it directly. I tend to hack off small lengths of solder and end up with lots of little bits of solder on the bench.
Glad to hear that the other caps on the Drake are standing the test of time. I wish the same could be said for all the caps in my Heath HW-101.
One thing caught my eye in Alan's video: The dial cord. You know you have become a true 2-B aficionado when you have actually gotten good at replacing the dial cord. It is something of a rite of passage. Perhaps this will serve as the basis for a future video by W2AEW,
Thanks Alan! And congrats on passing 4 MILLION YouTube views. People watch because your videos are so good.
Eric 4Z1UG is doing some really great interviews on his "QSO Today" podcast. I found the last three to be especially informative and inspirational.
Chuck Adams K7QO dispensed a lot of useful information about Muppet boards and construction techniques, but more importantly he put out a lot of wisdom about the hobby, especially on the importance of teaching and sharing knowledge.
The interview with Glenn Elmore N6GN presented many interesting technical ideas, including using WSPR on VHF and UHF, and using aircraft reflections as a Sporadic-E like propagation mode. He also mentioned "wing vortex" propagation. Glenn talked about how to use a drone and a special light-weight transmission line to get your VHF/UHF (or cell phone) antenna above the trees. (See above).
I found the conversation with Gerald Youngblood K5SDR both fascinating and a bit worrisome. Gerald is obviously a great guy, and he does a wonderful job of describing the technology behind SDR radios, linking it to the phasing techniques that hams have been using since the dawn of single sideband. He makes a strong case for the new SDR rigs, noting the absence of receiver-produced noise, the advantage of band-wide visual waterfall displays (even while noting that they tend to "make every ham an Official Observer"), and "brick wall filters that don't ring." But I got and uneasy feeling when he referred to non-SDR rigs as "legacy rigs." I found myself wondering how long it will be before all our rigs are required to be noise-less and all our filters skirt-less. Will there come a time when our beloved legacy rigs will be deemed unacceptable? (You can already hear this sentiment on the bands.) And how much room is there in this SDR world for the kind of homebrewing we do? ( I know, I know. I admit to feeling the presence of Ned Lud as I type these words.)
Great job Eric! And thanks to all the interviewees. We look forward to the interview with Pete N6QW.
From Wikipedia: Shannon showed an inclination towards mechanical and electrical things. His best subjects were science and mathematics, and at home he constructed such devices as models of planes, a radio-controlled model boat and a wireless telegraph system to a friend's house a half-mile away. While growing up, he also worked as a messenger for the Western Union company. His childhood hero was Thomas Edison, whom he later learned was a distant cousin. Both were descendants of John Ogden (1609–1682), a colonial leader and an ancestor of many distinguished people.
After their initial meeting, Thorp says, "we got right to it," and he spent about half his time for the next eight months working away with Shannon in that basement lab in Shannon's house, on one of Massachusetts' Mystic Lakes. In his paper, Thorp described the lab as a "gadgeteer's paradise," with what he estimated to be about a hundred thousand dollars' worth of electronic, electrical and mechanical items. The regulation roulette wheel, ordered from Reno for $1,500, was set up on an old slate billiard table.
Thorp describes Shannon as the "ultimate gadgeteer," and recalled in his paper that the man he met in that office was a "thinnish alert man of middle height and build, somewhat sharp-featured," and that "his eyes had a genial crinkle and the brows suggested puckish incisive humor." That humor would become evident as the two worked together at the house on the lake. Thorp wrote that Shannon taught him to juggle three balls, and that he rode a unicycle on a steel cable strung between two tree stumps. "He later reached his goal," he wrote, "which was to juggle the balls while riding the unicycle on the tightrope."
Michael Rainey, AA1TJ, Poet Laureate of QRP and Wizard of the Vermont Hobbit Hole found this drawing and put it on his face book page. It is clearly supportive of the "International Brotherhood of Electronic Wizards" theme of this blog, so I have shamelessly expropriated it. All for the cause Michael! I hope this indicates that OM AA1TJ is emerging from a too-long spate of radio-inactivity.
Michael says the drawing is from the 1920's children’s magazine, "Kodomo No Kuni" by Kiichi Okamoto. David Cowhig, WA1LBP, provides this translation:
Title "Ni-chan, I can hear it!"
The radio kid is saying something like:
-- Wait, no I lost it.
-- I can hear it, I can hear it, I've got it!
David notes: Sometimes Japanese use the katakana syllabary to add emphasis like we might with italics or exclamation points.
Clint KA7OEI sent us these inspiring photos of his 10 GHz transverters. FB Clint! The one on the top was built in 2005 and STILL looks like this. Note "CAT" component in the version pictured in the second photo.
I was thinking about spectral purity standards and the Si5351 chip. I realized that I didn't even know what the FCC standards for "close in" noise are. The standards for spurious emissions ARE well known, but these are for harmonics and parasitic emissions relatively far from the desired signal. What about unwanted signals CLOSE to the desired signal?
My old 2002 ARRL handbook indicates that the FCC has not established firm standards for this "close in" noise. (They call it "out of band" noise, but are clearly referring to noise that is close to the desired signal but spreading out beyond the desired bandwidth. Phase noise would be in their category.)
In the course of my Googling, I found the above spectral purity mask. I don't know where it comes from, but I think it is the kind of graph that would be very useful to us as we evaluate the merits and shortcomings of various frequency synthesizers. Would our DDS or PLL rigs fit in this mask?I think an Si5351 rig WOULD. According to KE5FX's measurements, at a mere 100 Hz from the center frequency, the Si5351 phase noise is already -90 db.
Does anyone have a similar mask showing current standards?
I still don't understand why so many folks believe that the Si570 is a useful part for homebrew rigs, but the Si5351 is not. Look at the numbers:
Si570 Clifton Labs measuring at 30 MHz carrier. At 10kHz from carrier: -109.6 dbc/Hz Silicon Labs web site (carrier freq not specified) At 10 kHz from carrier: -116 dbc/Hz
Si5351 KE5FX measuring at 19.99 MHz. At 10kHz from carrier: -127 dbc/Hz Silicon Labs measuring at 156.2 MHz. At 10 kHz from carrier -112 dbc/Hz.
Can anyone out there explain the technical basis for the belief that the Si570 is a useful part while the Si5351 is not?
It is important to keep things in perspective. ALL of these noise numbers represent VERY small noise levels. Let's keep is simple and assume a 100 watt carrier signal and a phase noise of -100 dbc/Hz. That means the phase noise per hertz would be .00000001 watts. That's watts/hertz. How much "noise power" would that represent in a typical SSB passband? Multiply by 2500 Hz and you get 25 microwatts. That's really low noise levels. Not enough to worry about. And as we've noted, we've happily used rigs with LC VFOs and crystal oscillators for all these years without every once measuring their phase noise.
Alan's video inspired me to do a little work with my Drake 2-B. Nothing major -- I was just making sure that the passband knob is in the right setting. I've complained that the Drake 2-B doesn't sound great on AM. I recently noticed that my BITX40 DIGI-TIA sounds surprisingly good with AM signals -- I just treat them as SSB signals and zero-beat the carrier with my Si5351 VFO. I wanted to try doing the same thing with the 2-B, and then make some comparisons. I only heard a few AM signals this morning, so I will try again later today and will report results here.
We needed an illustration today. I was having trouble finding something suitable. Then the Radio Gods (along with Joe Peltola and the artist N0UJR) provided this.Obviously I can relate to thebreadboard operation. I'm sure Pete can too. As for the mountain topping, that made me think of Colin, M1BUU. And of Wes, W7ZOI.
Thanks to Bob Crane, W8SX, for the link to this article. Those of us who are reading "The Martian" will find the mention of RTG power interesting (but hey, let's not try to put any plutonium in our rigs, OK?)
I've been hearing about this book for years, but until I watched this interview, I knew nothing about the author. Thanks Lady Ada. (And thanks to Farhan for the alert.)
As a native New Yorker, I'm pleased to include in the blog yet another reminder that the Big Apple is not all fashion and finance -- a lot of solder has been melted in my home town.
Paul Horowitz has a truly awesome bio. He got his ham license at age eight. QST tells us that lots of little kids do this, but unlike some of the youngsters we see in the magazine I suspect young Paul really mastered the theory. Paul Horowitz has "The Knack." Big time.
PhD from Harvard. Author of "The Art of Electronics." Pioneer in the Search for Extraterrestrial Intelligence. Carl Sagan is believed to have modeled the main character in "Contact" partly on Paul. Check out the wiki page:
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!)