Just go to http://soldersmoke.com. On that archive page, just click on the blue hyperlinks and your audio player should play that episode.
http://soldersmoke.com
Pete WB9FLW asked for this. This was an important article for me -- it paved the way for my entry into homebrew phone gear -- this article was the basis for my first DSB transmitter, built in the Azores.
I think Doug was a bit optimistic in saying that SSB operation was possible with this rig. Maybe it was possible for Doug, but for most of us DSB is just a LOT easier to get going than SSB. (I know that some people don't believe this, but I note that most of these folks have built neither DSB nor SSB rigs. It always seems easier before you start to melt solder.)
Be sure to check out the 10 meter DSB rig recently built by Mike WU2D. He has 6 or 7 good videos on this project, including this one: https://www.youtube.com/watch?v=xThoAMv4zrw
I've been thinking about balanced modulators, and I wanted to see how some of my early circuits performed. So I pulled this OLD Double Sideband rig off the shelf and fired it up. The balanced modulator -- and everything else! - worked fine, and I soon made contact on 17 meter SSB with Gene, AB9GK.
This was the first DSB transceiver that I ever built. I made this out in the Azores, probably in 2000 or 2001. Years later I had replaced the RF power amplifier with a "JBOT" (Just a Bunch of Transistors) designed by Farhan.
Over on my YouTube channel a comment came in from my friend Jack:
"Looking inside and seeing the o-scope probe in place while
the radio was on the air reminded me of neurosurgery where the patient is awake
and talking while the surgeon probes different brain regions soliciting
feedback. Sure, ham radio isn't neurosurgery, but it's not too far at times.
Also, you already have rocket science covered."
Here is an article about my build of that first rig:
I think the article captures well the trials and tribulations faced by new homebrewers, perhaps with the twist that comes from being out in the middle of the Atlantic ocean.
Mike WU2D is having similar fun with his homebrew 10 meter DSB transceiver:
I was struck by how similar Mike's early QSO experiences were with mine. We both put our DSB transmitters on the air before they made their way into real cabinets or boxes.
I think the article captures well the trials and tribulations faced by new homebrewers, perhaps with the twist that comes from being out in the middle of the Atlantic ocean.
Mike WU2D is having similar fun with his homebrew 10 meter DSB transceiver:
I was struck by how similar Mike's early QSO experiences were with mine. We both put our DSB transmitters on the air before they made their way into real cabinets or boxes.
Last month I was talking to Ira VP2EIH on my new 1712 SSB rig. Ira is interested in satellites. Talking to him caused me to dig up some old material about satellite operations. Here is a 2003 QST article about working the satellites from the Azores:
Regarding the usefulness of WD-40, during my time in the Azores John EI7BA once told me that WD-40 is, "the Pope's pee!" Apparently that is high praise in Ireland. It is indeed good stuff.
Messias CU2BJ is a Silent Key. I hope Ray CU3GC, WL7CDK is doing well.
6 weeks in the DR for Bill One contact on uBITX. More SW listening. Repaired my Chrome Book in Santo Domingo! Christmas Present for All: James Web Space Telescope launch
I spent most of January in the tropics, away from my workbench. This seems to have had a good effect on my 17 meter split TX/RX project. As I was leaving, heading south, I was thinking about several difficult options to deal with my spur problem (see previous blog posts). I thought about turning the transmitter into a transceiver by building a receiver board. I thought about putting San Jian frequency counters on both the transmitter and the receiver, then doing a visual numerical "netting" by just putting the two devices on the same frequency (I actually ordered 3 San Jian counters). The counter option was even more complicated than it at first seemed -- I would have to build a converter to shift the RX VFO frequency up. VK2EMU suggested a tube type "Magic Eye" (interesting idea, but also complicated). This was getting out of hand.
When I got back home, I took a new look at the problem. I decided to take one more shot at suppressing the 8th harmonic of the carrier oscillator. I had already built a new oscillator and buffer using the circuit from Farhan's BITX20. And I had put it in a metal box. Now I decided to do three things:
1) Tighten up the low pass filter at the output of the buffer by moving the cutoff frequency lower (to around 7 MHz) thereby getting a bit more suppression at 41 MHz
2) Try putting a series LC shunt circuit tuned to 41 MHz at the output of the carrier oscillator (between the oscillator and the buffer).
3) Reduce the voltage to the oscillator/buffer. I have this on a pot, so I can adjust it down to the point where the remnant of the harmonic is no longer audible, while keeping the main carrier osc signal sufficiently strong.
It seemed to work. I could now hear the desired frequency for spotting, without the confusing tone from the spur.
Why had I been able to do this back in 2002 in the Azores using a simple trimmer cap to ground? My guess is that I was using my Drake 2-B as the receiver. The trimmer cap to ground may have reduced harmonic output. And I was probably cranking back the RF gain on the 2-B to the point where I could hear the desired signal but not the remnants of the spur. I have no RF gain control on the Barebones Barbados receiver that I am using in this project.
So, what's the lesson from all this? Well, if you are faced with a serious technical problem, and you find yourself considering complicated and difficult solutions, go to the Dominican Republic for about a month (especially if it is January or February), and then take another look at the problem when you return. If you are unable to travel this far or for this long, taking a walk or taking a weekend break from a troublesome problem will likely have a similar mind-clearing effect.
The video above shows part of a February 1, 2022 QSO with Gar WA5FWC using the split TX/RX 17 meter rig. Gar is an amazing long-time SSB homebrewer who got his start with phasing rigs back in the day.
The other day I was complaining to Pete N6QW that 17 meters still seems to be in very poor shape. I can hear 6Y6Y around mid day, but I don't often hear Europeans. I did year my friend Mike EI0CL yesterday on 17, but conditions were not good. Pete asked, "Where is Cycle 25?" Good question. The Space Weather Center has the answer.
Their Solar Cycle Progression page is up-to-date. With the slider below each chart you can go back as far as 1750. Check out Cycle 19. I was born near the peak (TRGHS). Pete was on the air during that cycle. Cycle 23 also looked pretty good. I was out in the Azores then (2000-2003) -- no wonder I could work VK and ZL with a 5 watt DSB rig.
I like the little solar conditions widget that has appeared in the left hand column of this page, and I am grateful to the provider, but the widget just doesn't update regularly. So I think I'm going to switch to a link from the Space Weather Prediction Center that shows the numbers we really need: Solar Flux Index (SFI), Sunspot Number (SN), A index, K index. (Please let me know what you think about this change.)
Here is the link to the Solar Cycle Progression Charts (be sure to use the sliders):
More on this project in due course. Lots of soul in this machine.
I'd forgotten about this article -- thanks to Pete Eaton for reminding me. Click on the images for a better look at the article. For an even clearer view, download the images and then open them on your computer.
In SolderSmoke Podcast #234, I said that I was scrutinizing the filter from the Swan 240 that I had picked up around 1994 in the Dominican Republic. I cannibalized it out in the Azores in the early 2000s and used the parts to build -- among other things -- my first SSB transmitter. I never really focused much attention on the filter that I pulled out of that old rig -- I was just happy that it seemed to work. But I am now older and wiser, and I have some test gear that lets me look at the passband of that filter.
First, take a look at what it is supposed to look like. This is from the manual. Yikes! That passband looks far from flat. I can almost hear homebrewers around the world shrieking in horror and disgust.
Above is a description of the filter, and the schematic, again from the manual.
Here is what my extracted and somewhat re-built filter looked like in my NanoVNA (more shrieking!). The dip in the passband is a lot worse here -- it looks like 10 db vs. 3 db in the manual. This is probably because I'm not even attempting any impedance matching on the filter -- it is just seeing the 50 ohms in and out of the NanoVNA.
Here is my 2002 attempt to rebuild the filter and put it in my SSB transmitter, along with my more recent attempt to flatten the passband. I no longer had the adjustable coil L8, so I made my own coil based on guidance from Ben Vester W3TLN's January 1959 QST article on "Surplus-Crystal High-Frequency Filters." (Ben had an early influence on Pete Juliano's tube-rig designs.) In the picture above I have 1k pots between the filter and the input and the output of the NanoVNA, as described by Nick M0NTV.
Adjusting the 1 k pots, I could smooth out the passband quite a bit. Measuring the pots and adding the 50 ohms of the NanoVNA, it looks to me like this filter is smoother with about 280 ohms at the input and output. I may build two matching networks or some transformers. Some TIAs may also be needed.
Don't get me wrong -- I'm a huge fan of Doug DeMaw. His books and articles are a treasure trove for ham radio homebrewers. Also, Doug was an honest guy who admitted in the preface to his QRP book that at times he did not fully understand the circuits he was building; that kind of honesty is rare, and is very helpful to amateurs who struggle to understand the circuits we work on.
But everyone makes mistakes, and Doug made one in his "W1FB Design Notebook." I present it here not as a "gotcha" effort to nitpick or sharpshoot a giant of homebrew radio, but because this error illustrates well the depth of the 75 LSB/20 USB myth, where it comes from, and how important it is to really understand sideband inversion. Here is the mistake:
That's just wrong. A receiver built like this will not allow you to listen to 75 LSB and 20 USB "without changing the BFO frequency." (Am I the first one to spot this error? Didn't anyone build this thing, only to discover that it, uh, doesn't work?)
Here's a little drawing that I think illustrates why the mythical scheme will not work:
All confusion about sideband inversion could be avoided with the simple application of what I think we should call "The Hallas Rule":
"Sideband reversal occurs in mixing only if the signal with the modulation is subtracted from the signal that isn't modulated."
Be careful here: I think some arithmetic carelessness is responsible for much of the myth. Taking the difference frequency is not enough to produce sideband inversion. Read the Hallas Rule carefully: For sideband inversion to occur, the signal with the modulation must be subtracted FROM the signal without the modulation.
---------------------------------------------
About the Swan 240's SSB generation scheme:
I first stumbled on this problem when building my first SSB transmitters in the Azores. I was using a VXO, and a filter pulled out of a Swan 240 (5.173 MHz). I started with VXO crystals at around 12.94 MHz. The rig worked, but I couldn't pull the VXO crystals very far. So I switched to crystals at around 23.3 MHz (you can pull higher frequency crystals farther). But look what happened: My Carrier Oscillator frequency had been set up to receive USB signals on 17 Meters. With the 12.94 MHz rocks, that worked fine: 18.150-12.977 = NO INVERSION. But it all changed when I went to the 23 MHz VXO rocks: 23.323-18.150 = INVERSION! This had me scratching my head a while. I had to draw myself little spectrum pictures (like the one above) before I realized what had happened. To get it to work -- to get it to produce USB on 17 meters -- I had to move the Carrier Oscillator to the other side of the passband. Good thing that Swan 240 came with TWO BFO crystals (5.1768 MHz and 5.1735 MHz). I just had to change the crystal.
For 75 and 20 meters, the Swan 240 uses the correct 5.173 MHz filter with a 9 MHz VFO to get the happy situation of 75 meter LSB and 20 Meter USB WITHOUT changing the BFO/Carrier Oscillator frequency. This is the Mythbuster scheme. Unlike Doug's receiver, it works. The scheme also works in the Swan 240 on 40 meters because for 40 the Swan rig has the VFO running from 12.073 MHz to 12.513 MHz. Here too, no change in the BFO/Carrier Oscillator frequency is needed. But the Swan recommended a modification that would allow operation on 20 LSB and 75/40 USB! It used a BFO/Carrier Oscillator crystal of 5.1765 MHz and a switch mounted on the front panel. Luckily, my junker Swan (acquired from HI8P in the Dominican Republic) had the second crystal -- mine was 5.1768 MHz. It was that crystal that allowed me to get my Azorean SSB transmitter to work using the 23.9 MHz VXO rocks.
Dean KK4DAS asked me to speak to our local radio club, the Vienna Wireless Society. It was a lot of fun. I talked about my evolution as a homebrewer, some of the rigs I made, the moments of joy, and the tales of woe. You can watch the presentation in the video above. I was really glad to be able to explain in the presentation the importance of people like Pete, Dex, Farhan, Wes, Shep and even Dilbert. I was also pleased to get into the presentation the N2CQR sign that Peter VK2EMU made for me. Thanks Peter! Here is the URL to the YouTube video (also above): https://www.youtube.com/watch?time_continue=3414&v=VHSr-v4QO7Q&feature=emb_logo And here are the PowerPoint slides I used: https://viennawireless.net/wp/wp-content/uploads/2020/06/VWS-presentation-Rig-here-is-homebrew.pdf
This one is not about radio or electronics, but over the years many SolderSmoke listeners have written in saying that they liked the opening "travelogue" portion of the podcast. This book may appeal to them. It might also be of interest to spouses who've been hearing about these "soldersmoke people." This would be, I think, a good "beach book."
The title is: "Us and Them -- An American Family Spends Ten Years with Foreigners"
Here's the description:
What happens if you take an American family and send them to Europe for ten years? In the summer of 2000, Bill and Elisa Meara, accompanied by 2 year-old Billy and 4 month-old Maria, left their home in the suburbs of Washington, D.C. and moved to the Azores. There they experienced the highs and lows of diplomatic life on a small distant island. After three years in the Azores, they spent four years London and three years in Rome.
Overseas they lived in two houses and two apartments, went to five schools, used four different health care systems, experienced one earthquake, 9-11, the terrorist attack on London, tea with the Queen, the election of Barack Obama… and all the ordinary things that families go through.
They lived mostly with the locals, learned Portuguese, Italian, and a bit of Cockney, and made many friends (foreign friends!) They returned to the United States in 2010 with a changed view of the world. This is their story.
In print form is available from Amazon and from Lulu:
Wow, it is very clear that the radio gods are pleased with my BITX efforts! I had my first QSO on the new rig today. And it was with a station in my old home, the place where I got my start in 17 meter homebrew phone: THE AZORES! CU7MD. Very cool.
I called CQ on 20m CW for a couple of hours yesterday afternoon with no response. With the cadence of my own Morse tugging at my eyelids, I was suddenly shaken awake by a brisk signal returning my call and signing CU2BV. I snapped out a 579 report and turned it over. The dits and dahs in my headphones told me it was Fernando; operating from São Miguel island in the Azores. He reported a weak but solid copy (529) of my fifty milliwatt signal.
Here's the radio that I used yesterday. The one-transistor transmitter is to the left of the red relay on the top board. The single transistor is a germanium surface-barrier device made by Philco in August of 1958. To the right of the relay is a two-transistor time-delay circuit used to switch the antenna between the transmitter and the receiver. My receiver on the lower proto-board is a reproduction of my first shortwave receiver: a $7 Japanese kit that I bought at Radio Shack when I was 13 years-old.
Fifty milliwatts is some twenty-four times less power than was used by an old double D-cell flashlight. I later learned that my signal was nearly simultaneously picked up by an automated receiver located just west of Dusseldorf, Germany.
Snowy Vermont to the lush Azores - some 1500miles off the coast of Portugal - with less power than is consumed by a beeswax candle...is it any wonder that I love radio? ;-)
I am writing to tell you what a GREAT book "Solder Smoke" is. I really enjoyed it and I am amazed at how similar our paths are regarding electronics, ham radio and our journeys around the world.
Although I am 16 years older than you I, too, got my start in radio at an early age: about 10, after I got nailed by my dad's console SW/AM radio prior to a Cub Scout meeting one evening. I just had to figure out how I received a shock from that big old receiver, which led me to a life long pursuit of the elusive electron, an interesting 50 year career in ham radio, a 20 year career in the USAF (Tech Controller, AFSC: 307), and ultimately teaching vocational electronics in the State Correctional Institution at Dallas, Pa.
During my AF career I spent almost 17 years overseas: two tours in Japan (KA2AA--this was prior to recip licensing as we had the Far East Amateur Radio League in the SOFA), a three year tour at Lajes Field, Terceira Island, the Azores (CT2BH--this was prior to the Azores receiving independence from Portugal in 1976), a five and a half year tour at RAF Mildenhall, UK (G5CSU), and a brief stint in W.Germany (DA2NE) while working with 10th SF Group at Bad Tolz and SOTFE in Patch Barracks. Had 18 months in the 3rd Mobil Comm Gp in Tinker AFB, OK, and a twilight tour at Langley AFB, VA.
The three years in the Azores was from 1970-73....it was extremely difficult to obtain a ham license at that time and there were only 9 of us licensed in the entire archipelago, as I recall. I was attached to the 1936 Comm SQ, and all we had for comms to support theUS Forces Azores mission were three HF ISB shots: one to Andrews AFB, MD, one to Rota, Spain and the other to RAF Croughton, UK. During that three year period I REALLY learned about HF comm and propagation. I was on duty the day, in 1973, when "the ionosphere turned off"! WE had a SID of such magnitude that it blotted out everything, and I DO MEAN EVERYTHING! We were lucky to hear AFRTS on the hill by the MARS station! During that tour we also performed comm support for the US Navy's Sea Lab project on Sao Maria, which was part of the SOSUS system. Ultra cool stuff!!! On more than one occasion during a mid shift, the Comm SQ chief of maintenance, CT2BC, would snag me from tech control, and we'd go intoLajes Airways (right down the hall) and grab a Scope Control Level, point the two HUGE LPAs toward the states and work a little DX on 20M !! Definitely NOT QRP! All this under the guise of "quality control"! It pays to have friends in low places!
During my UK tour, we initially lived off-base at Bury St. Edmunds. I had a Ten-Tec PM-2B and a tuner which I loaded into a chain link fence behind our house. I quickly worked Collin Turner, G3VTT, and soon became a card carrying member of the G-QRP-Club (#622) in 1979. To celebrate my 34th birthday, my wife Pat (KB3MCT) and Jo Dobbs, wife of George Dobbs, G3RJV, put together a surprise party for me after a Saturday at the RSGB convention near Birmingham. George Burt, GM3OXX along with Ronny, GM3JJG, furnished the haggis....and the single malt....needless to say we did have fun; all 25 of us packed into RJV's home!
Hey, sorry for being long winded. Our backgrounds and travels are uniquely intertwined. Thanks for writing "Solder Smoke". I am procuring a hard copy (I read it on my Kindle) for my wife, as your insight into the "why things work the way they do" are perfect for her to help her with obtaining her Extra. I only wish I had it when I was teaching my electronics classes in prison. It would have made my job easier, that is for sure.
Stay well, and I hope we can meet one of these days. In the mean time, I have to pull my Meade ETX out of storage and start watching the sky, and finish building about four model rockets for an upcoming launch weekend here in North Georgia.
Rich Arland, K7SZ Dacula, GA
Author: "The ARRL's Low Power Communications, the Art and Science of QRP (all four editions)
September 23, 2012 Trip to the Dominican Republic: Puerto Plata and Samana Evading Hurricane Isaac Honda Accord as an emergency generator On the air on 75 and 40 AM 17 Meter Azores rig works...THE AZORES! Working (STILL!) on 20 meter DSB rig. Soon to be JBOTed Building model rocket with Billy Book review: "Martian Summer" Einstein on staying young Primo Levi on QRP HOT IRON: G3ROO's Regen wins West Country prize Commodity Investment Opportunity: SILVER MICA! MAILBAG: SolderSmoke is on 478 THz in Salt Lake City WA3EIB's HT-37 Radio-Erotica in Hallicrafters Ad
Once again, die-hard QRP guys should probably look away at this point...
My Cycle 23/Cycle 24 refurbishing project continues. The JBOT amplifier in the 17 meter SSB rig is now working nicely, but unfortunately just as I got ready to make some contacts, the Coronal Mass Ejection hit us and conditions on 17 deteriorated badly. Looking for something to do, I noticed that in some pictures of my old Azores station, sitting alongside the SSB transmitter there was a small cabinet with a QRO/QRP switch on the front panel. Ah yes! My Ramsey Kit linear amplifier! This is a MOSFET-based device. Mine was designed for 20, but I changed the low pass filter and put it on 17. Later, in Italy, it went on 20 meters and for some reason I went back to the 20 meter low pass filter.
Yesterday I blew the dust off this thing, pulled out the 20 meter LP filter and replaced it with a filter that will let my 17 meter RF reach the antenna. Today I fired it up. Wow! 20 Watts! Look out 17 meters!
I really like the QRO/QRP switch -- it gives me the opportunity to lean back and say (just like the big guns) "Wait a second Old Man, let me turn on my LINEAR!" I even have a little fan in the box that you can hear when I go to the QRO position. Unfortunately it doesn't make the lights flicker. But we can dream...
Even though one of their Coronal Mass Ejections is due to hit us soon, the radio gods have been quite kind to me this morning. I installed the JBOT amplifier board in the 17 meter SSB transmitter that I had built out in the Azores during the last solar cycle. The board went in without any trouble. And I was a very surprised when it DIDN'T break into oscillation and instability! Holy Cow! This one was stable from the start! Even when connected to my antenna! Eureka!
The rig still needs some peaking and tweaking. I'm only getting about 2-3 watts out and I should be getting 4-5. I did a quick and dirty "by ear" alignment --- I just listened to my own signal with my trusty Drake 2-B and moved the carrier oscillator freq around a bit until the SSB audio sounded good (you never have to do that with DSB!).
For those of you not familiar with this rig, here is some background: -- Built on the chassis of an old Heath DX-40 -- Crystal filter at 5.174 MHz. Filter rocks and carrier oscillator rocks from an old Swan 240 I picked up in the Dominican Republic from Pericles Perdomo HI8P (SK). -- Based on a design published in SPRAT by Frank Lee, G3YCC (SK). --Heterodyne oscillator is a G3RJV Universal VXO circuit running at around 23.3 MHz. -- That orange cord to the big meter that you are no doubt wondering about is just a little circuit that monitors total current drawn by the rig. It bounces up and down as I talk. I put it in there mostly because I wanted to make use of a beautiful old Simpson meter that I picked up in 1973 at the Crystal Radio Club (W2DMC) in Valley Cottage, New York.
Going around, clockwise from below the meter: G3RJV VXO, carrier oscillator and two diode balanced modulator board, crystal filter (with NE602 mixer and post-filter bandpass filter to the left), JBOT PA. Audio amp (using op amp) below the chassis. T/R relay in the center (antenna changeover relay below the chassis).
"SolderSmoke -- Global Adventures in Wireless Electronics" is now available as an e-book for Amazon's Kindle.
Here's the site:
http://www.amazon.com/dp/B004V9FIVW
Bill's OTHER Book (Warning: Not About Radio)
Click on the image to learn more
Where are the readers of SolderSmoke Daily News?
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SolderSmoke Co-Host and Master Homebrewer
Dean Souleles KK4DAS
With beret and with a Michigan Mighty Mite in hand
Linux Mint, QRP, & C / C++ Compilers
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Greetings:
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December 11, 2024. We take things for granted.
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MeSQUAREs alternative - 1/32" board
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In this episode we give you the buyer's guide to holiday cheer. The team
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The November - December 2024 SARC Communicator
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*Another BIG issue*
The final issue of the year. The November-December Communicator, digital
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Hollow-State Design, 3rd Edition
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Hollow-State Design, 3rd Edition is available from: Lulu Press:
tinyurl.com/hollowstatedesign3 eBay: search for “hollow-state design”
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2000 47pF Caps ...
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An unexpectged package arrive in the mail today. Did you ever wonder what
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New QRP Cluster From OM0ET and OM6APN
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By DX EXPLORER
DX EXPLORER
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40m SSB Tramping Rig
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Please see my YouTube channel for details of the build.
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QRP Labs shop!
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All QRP Labs kits may be ordered online securely at the shop, with PayPal
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