Polyakov (RA3AAE) Direct Conversion Receiver: 40 meter DC RX with VFO at 3.5 - 3.6 MHz (with video)

I've been reading about Polyakov (or "sub-harmonic") Detectors for a long time: 

https://soldersmoke.blogspot.com/search/label/Polyakov--Vladimir

But until now, I never built one.  Recently,  Dean KK4DAS and the Vienna Wireless Makers group have been building a Direct Conversion receiver.  Their receiver uses an Si5351 as the VFO, but of course Dean and I have decided to try to do things the hard way by building non-digital VFOs.  At first we just came to the conclusion that my earlier Ceramic Resonator VFO wasn't much good (it drifted too much).  This led us into standard Colpitts and Armstrong VFOs, and the fascinating world of temperature compensation.  Then I remembered the Polyakov circuit -- this would allow us to use a 3.5 MHz VFO on the 7 MHz band.  Lower frequency VFOs are easier to stabilize, so I started building my first Polyakov receiver.  You can see the results (on 40 meters) in the video above. 

I started working with a circuit from SPRAT 110 (Spring 2002). Rudi Burse DK2RS built a Polyakov receiver for 80 and 40 that he called the Lauser Plus.  (Lauser means "young rascal" or "imp" in German.) For the AF amplifier, I just attached one of those cheap LM386 boards that you can get on the internet.  With it, I sometimes use some old Iphone headphones, or an amplified computer speaker. 

The Polyakov mixer is a "switching mixer."  The book excerpt below shows how I understand these circuits.  The enlightenment came from the Summer 1999 issue of SPRAT (click on the excerpt for an easier read): 

Leon's circuit shows us how a simple switching circuit in which the switches are controlled by the VFO can result in an output that has the sum and difference components. That is the hallmark (and most useful part) of real mixing.  Remember -- we say that mixing happens in non-linear circuits when the passage of one signal depends on what is happening with the other signal.  A switch is as non-linear as you can get! And that switch is being controlled by the VFO.  

In a Direct Conversion receiver we usually run the VFO at the operating frequency. This results in audio just above and just below the operating frequency. 

The Polyakov Direct Conversion circuit is a bit different.  It has the switches (the diodes)  turned on twice each cycle:  When the VFO voltage goes to a positive peak, this turns on one of the diodes.  When the VFO goes to a negative peak, this turns on the other diode.   So in effect the switch is being turned on TWICE each cycle.  So with the Polyakov you run the VFO at HALF the operating frequency.  For a DC receiver designed to run around 7.060 MHz, you build a VFO at around 3.53 MHz.  This has some immediate advantages.  My favorite is that it is easier to get a VFO stable at a lower frequency.  It is easier to stabilize a VFO at 3.53 MHz than it is at 7.060 MHz. 

When you open that SW 1 switch in the Lauser Plus, you no longer have a Polyakov mixer.  Now you just have a diode mixer.   It will be opening and closing once each cycle at the VFO frequency.  DK2RS used this to cover not only the 40 meter band (in Polyakov mode) but also the 80 meter band (in single diode detector mode).  That is why DK2RS has that big variable capacitor in the input circuit -- that LC circuit needs to tune all the way down to 3.5 MHz and all the way up to around 7.3 MHz.  (I used a coil of about 6.5 uH to do this.) 

With just one diode and operating at 80 meters, it works, but not as well as it does in the Polyakov mode on 40.  I can pick up 80 meter signals, but in this mode there seems to be more of an "AM breakthrough" problem. "Experimental Methods in RF Design" on page 8.11  describes what is going on (the last sentence is most relevant here): 

Here are some very good links with information on the Polyakov receiver: 

LA8AK on Polyakov: http://noding.com/la8ak/c21.htm

LA8AK's Home Page: http://www.agder.net/la8ak/index1.htm

LA8AK SK: http://www.agder.net/la8ak/   Almost seventeen years after his death he continues to help his fellow radio amateurs through his web sites.  TNX OM!  FB! 

BH1RBG: https://sites.google.com/site/linuxdigitallab/rf-ham-radio/dc-polyakov-based-first-dc-receiver

Hack-A-Day on Polyakov: https://hackaday.com/2015/11/15/polyakov-direct-digital-synthesis-receiver/

I will post a video tomorrow showing the receiver in operation on 80 meters.  

Three cheers for Vlad Polyakov, RA3AAE

Model Rocket Lands Like a SpaceX Falcon 9

I had a blog post about this in 2018: 

https://soldersmoke.blogspot.com/2018/06/rockets-and-microcontroller-videos.html

He has finally achieved the very difficult goal of landing his model rocket just as SpaceX does with its Falcon 9.  Check out the video above.  

It was also very cool to see him building the rocket, using a very wide range of electronic, software and metalwork skills.  

Hack-A-Day has a good post explaining how he did this: 

https://hackaday.com/2022/08/05/bps-space-succesfully-lands-a-model-rocket/

Congratulations to BPS.space!  

Video of SolderSmoke Podcast #239

Link to audio Podcast and notes on the episode: 

 https://soldersmoke.blogspot.com/2022/08/soldersmoke-podcast-239-hex-dx-vfo-temp.html

SolderSmoke Podcast #239: Hex DX, VFO Temp Comp, DC RX, Polyakov!, DX-100, Wireless Set, Farhan's "Daylight Again" HDR rig, MAILBAG

N2CQR Hex Beam Aimed at Europe

SolderSmoke #239 is available for download: 

http://soldersmoke.com/soldersmoke239.mp3

TRAVELOGUE: 

James Webb Space Telescope.  Mars returning to opposition in early December.   

BILL'S BENCH

Hex Beam K4KIO - on roof – TV Rotor – 20-17-12  Lots of fun.  Working Japan regularly, Australia, South Africa on long path 17,000 miles.  52 countries SSB since July 11.

VFOs and Temp stabilization.  Dean KK4DAS found my ceramic resonator VFO for DC receiver drifty. He was right.  So I built a real LC Colpitts VFO.  Got me into temp stabilization.  A new hobby!  An obsession.  HT-37 and Ht-32 parts. Ovens?  WU2D’s second VFO video.  Understanding thermal drift and how to address it. Split stator caps.  Cut and try.  

Built a Polyakov DC Receiver. https://soldersmoke.blogspot.com/2010/03/polyakov-plus-dual-band-receiver-with.html  Lauser Plus.  Lauser = Imp or Young Rascal!  DK2RS.  He used a ceramic Resonator VXO at 3.58 MHz.   Mine works great on 40 with VFO running 3.5 -- 3.65 MHz. See schematic below. 

On 40 AM with DX-100 and MMMRX.  DX-100 died.  12BY7 VFO buffer went bad.  How common is failure in this tube type?  Nice QSO with Tim WA1HLR about the DX-100.

Got my Dominican license:  HI7/N2CQR!  SSSS on the way.   Thanks to Radio Club Dominicano and INDOTEL.

Getting more active in the Vienna Wireless Society.  

BOOK REVIEW:  

"The History of the Universe in 21 Stars” by Giles Sparrow.  Written during the pandemic.  Published by Welbeck, in London. https://www.amazon.com/History-Universe-21-Stars-imposters/dp/1787394654  Also:  From “Atoms to Amperes” by F.A. Wilson available for download.  See blog.

SHAMELESS COMMERCE DIVISION:   

Todd K7TFC getting ready to launch “Mostly DIY RF.”   I used his TIA boards in my 1712 rig.  He will have boards like this and much more.  Stay tuned.

I need more viewers on YouTube.  They want 4,000 hours IN A CALENDAR YEAR!  Please watch!

FARHAN’S NEW “DAYLIGHT AGAIN” RIG.  Analog.  VFO.   Comments, observations. We need to get him on the podcast.  Maybe two shows: SDR and HDR. 

PETE'S BENCH

Time very limited. But still sharing lots of tribal wisdom.

Wireless set with tubes!

Tool recommendation – Air compressor

 MAILBAG:

Farhan VU2ESE – Speaking of big antennas “Whenever I look at the huge construction cranes in Hyderabad, I always think how one could make 160m, 4 element yagi using it as a boom..”

Todd K7TFC in Spain, spotting Log Periodics in Madrid.

Andreas DL1AJG:  Can Biologists fix Radios?

Janis AB2RA Wireless Girl.  Expert on Hammarlunds.  And was my first contact with the Tuna Tin 2. She too was HB!

Peter Parker VK3YE on Owen Duffy VK1OD

Lex PH2LB on homebrew radio

Would this really be homebrew?  Mail from H-A-D article on FM receiver

F4IET a DSB rig from France

Ciprian got his ticket YO6DXE    

Josh G3MOT sent us a good video about the Vanguard satellite and IGY.

Dave Wilcox K8WPE bought Chuck Penson’s Heathkit book.

Rogier -- So many great articles and links from PA1ZZ

Bill AH6FC  Aloha. Retiring.  Wants to build.  Mahalo!

Grayson KJ7UM  Working on an Si5351.  Gasp.

Mike KE0TPE viewing YouTube while monitoring 6 meters.   He will have a lot of time to watch!

Chris KD4PBJ spotted Don KM4UDX from VWS FB

Mark WB8YMV building a superhet.  Having trouble with 455 kc IF can filter.

Walter KA4KXX Great comment on the Daylight Again rig. 

Ramakrishnan Now VU2JXN was VU3RDD.  Found lost Kindle with SolderSmoke book on it. Building SDR rig from junk box.  Trouble with the LM386. 

Pete, Farhan and Tony:  Shelves of Shame

Daylight Again by Farhan

The Polyakov receiver I built yesterday (from SPRAT 110, 2002!)

Farhan Takes us Back into the Daylight -- An Analog Rig with a Homebrew Crystal Filter and an LC VFO

 

There is so much radio goodness in this rig and in the blog post that describes it.  Farhan's blog post will keep us busy for a long time.  There is much to learn there.  But perhaps even more important is his larger view of the role of analog circuitry in ham radio.  Here are a couple of excerpts from his introduction: 

 Here is the memo : The analog never died. The world is analog all the way, until you descend into Quantum madness. The antennas are analog, Maxwell died a content, analog man. Our radios, ultimately, are analog machines and we are all analog beasts too. Amateur Radio technology has evolved into the digital domain. However,  it has only made it easier for us to do analog with computers to simulate and print our circuits.  So, it’s time to bid good bye to our Arduinos and Raspberry Pis and build an Analog Radio for ourselves. So let’s see what we can achieve in hindsight, a return to our native land and a rethink of our approaches. The radio is called Daylight Again, a nod to being back at the FDIM in 2022 after a gap of two years. It is named after the Crosby, Stills, Nash and Young’s song that had been humming all the time while put this radio together, emerging after 2 years of lockdown.  This radio that took two days to come together, no actually two years! That’s: parts of it got built and stowed away, thoughts were struck in the shower, questions popped up during early morning cycle rides and notes and circuits were scribbled in the notebook.  I must take the first of many diversion here: I hope you all maintain a notebook. Write down the date and whatever you thought or did on the bench and the result. Nothing is trivial enough to leave out. Wisdom comes to those who write notes.  I started to build this on Saturday the 14th May and I checked into the local SSB net on Monday morning, the 16th May 2022.

AND

Having clean VFO  is the most important way of increasing the dynamic range of your radio. A free running JEFT VFO that has sufficient power and a good Q components, will be unmatched by any synthesized or direct sampling radios. The math is all on the side of the free running VFO. We are talking -150 db/Hz at 10 KHz spacing, by comparison the Si5351 is -125 db/Hz, it is 300 times worse.

That is just part of the intro.  We should all study the rest of Farhan's blog post very carefully and incorporate the wisdom into our new rigs: 

Here is the blog site: 

https://www.vu2ese.com/index.php/2022/08/04/daylight-an-all-analog-radio/

Enough of the darkness.  Step into the daylight my friends. 

Can a Biologist Fix a Radio?

 

Andreas DL1AJG (who in real life is a professional biologist) sends us this excellent article about how biologists approach problems in living cells as opposed to how engineers or technicians approach problems in broken radios. 

This excerpt from the 2002 article gives you an idea of the tone and content of the article: 

"... I started to contemplate how biologists would determine why my radio does not work and how they would attempt to repair it. Because a majority of biologists pay little attention to physics, I had to assume that all we would know about the radio is that it is a box that is supposed to play music. How would we begin? First, we would secure funds to obtain a large supply of identical functioning radios in order to dissect and compare them to the one that is broken. We would eventually find how to open the radios and will find objects of various shape, color, and size (Figure 2). We would describe and classify them into families according to their appearance. We would describe a family of square metal objects, a family of round brightly colored objects with two legs, round-shaped objects with three legs and so on. Because the objects would vary in color, we would investigate whether changing the colors affects the radio's performance. Although changing the colors would have only attenuating effects (the music is still playing but a trained ear of some can discern some distortion) this approach will produce many publications and result in a lively debate..."

Andreas points to diagrams in the article (see below).  The first (A) shows how the biologist might view the radio.  The schematic (B) shows how engineers or technicians view it: 

As I read the article, I was reminded of the wise advice frequently dispensed through the SolderSmoke podcast:  Do not look at a schematic as one single circuit.  Instead try to see it as a number of subcircuits.  Build and test these subcircuits separately.  Join them together only after each subcircuit is found to be working. 

Here is the link to the 2002 article in Cell by Yuri Lazebnik:  https://www.cell.com/fulltext/S1535-6108(02)00133-2

This is all really interesting.  I will share this with my son who is involved now in biological research. 

In addition to his day job as a biologist, Andreas is a homebrewer of radios. Here is a pictures he sent to us back in 2019 of a regen receiver that he built: 

Andreas asks if he might need an old Boatanchor radio to work on to improve his electronics/physics skills.   I'd suggest staying away from the older tube stuff.   Stick with the BITXs -- homebrew one, stage by stage.  And indeed,  use the engineering approach to the electronics!  

Home-Brew!

Sometimes it is good to take a look at how other people home brew different kinds of things.  Here is a fellow in Ukraine that really HOME brews.  

I think this FB video is a good place to start: 

https://fb.watch/ex9YG4EFJJ/

Here is his YouTube channel: 

https://www.youtube.com/channel/UC_nrEDtq-0OQEVupubH_QuQ/featured

Linear Tuning in the HT-37

I just kind of like this picture.  This is the HT-37 dial that came with the HT-37 VFO assembly I recently bought.  Note the retro designation: KILOCYCLES.  And note the nice, even, linear spacing of the VFO. This VFO runs 5 -5.5 MHz.  The circuit is a series-tuned Clapp.  That circuit seems to be one of the secrets of getting linear tuning -- to avoid the common situation of having all the upper frequencies kind of bunched together at the end of the capacitor's tuning range.  I notice that this circuit was used in the Galaxy V VFO and in the VFO of the Yaesu FT-101, both notably linear in their tuning.   

Another HT-37 VFO -- No Temperature Compensation Trimmer Capacitor?

Is that thing beautiful or what?  That is the VFO assembly from an HT-37.  This one includes the fly-wheel mechanism.  It tunes 5 - 5.5 MHz.  I'll probably replace the tube with an FET, but mostly keep it as is for use in a future transceiver.  It is built like a battleship.  Hallicrafters did not mess around with the solidity of VFO construction.  

I was a bit disappointed when I did not see the split stator temperature compensation trimmer cap that was present on the Hallicrafters variable cap that I bought back in February 2021: 

https://soldersmoke.blogspot.com/2022/02/differential-temperature-compensation.html  

I took a look inside my own (beloved) HT-37 and saw that it too lacks the temp compensation trimmer that came with the February 2021 variable cap.  Could it be that the February 2021 seller had the source wrong?  Could he have in fact been selling me the variable cap from an HT-32?  Or could it be that Hallicrafters added this split stator temp compensation capacitor to later versions of the HT-37?  

Hallicrafters patented the split stator temp compensation circuit (U.S. patent #2718617).  Chuck Dachis says in his book about Hallicrafters that the company had perfected this circuit by 1957.  

An HT-32B transmitter was selling for $725 in 1963.  That's $7020 in today's money.   Wow, and that is just for the transmitter!  

Software, Hardware, and Rockets -- T-Zero Systems (videos)

There is a lot of really cool stuff in these videos.  I am a hardware guy, devoted to HARDWARE Defined Radios.  But these videos are a reminder of the importance of software, of the things we could never do with our older, analog technology.  

Watching him build his rockets, I even get ideas for my comparatively low-tech workshop: that small jig-saw that he used to cut the rocket fins looks like something I really need. 

This fellow is a professional rocket scientist who likes the work enough to take it home as a hobby.  It looks like he is working in Florida.  

Watching the videos and hearing him discuss the joys and frustrations of his endeavors reminds me a lot of what goes on in ham radio homebrewing. He often seems to have the same kind of haunted, obsessed look in his eyes that we are so familiar with.  That is what Jean Shepherd must have looked like when he couldn't get his Heising Modulator to work properly.  Oh, the humanity!   

Here it the YouTube channel: https://www.youtube.com/c/TZeroSystems

Here are some videos and stills of our 2017 rocket launches from Virginia's Shenandoah valley: 

https://soldersmoke.blogspot.com/2017/05/still-photos-and-slow-motion-video-from.html

Go WERRS! 

IGY! Science and the Vanguard Satellite in 1959 (video)

The International Geophysical Year (1958-1959) was a very scientifically productive period.  It is really amazing how much we learned from tiny satellites like Vanguard.  Like the shape of the Earth!  Great stuff in this video.  

Very cool telescopes and cameras set up around the world to monitor the early satellites.  And there is a quick mention of ham radio efforts to monitor the new spacecraft. 

Thanks to Josh G3MOT for sending this to us. 

Go IGY! 

A Surprisingly Good Movie from the Late 1960s: "The Ham's Wide World" (Video)

I found this movie to be surprisingly good.  Narrated by Arthur Godfrey, it features Barry Goldwater, and a lot of other hams.  There is a homebrewer too!  Lots of  old rigs we know and love:  a Drake 2-B, a couple of Galaxy Vs, a Benton Harbor lunchbox, Heathkit SB-series rigs, many Swans, and was that an HQ-170 that I saw in there?  There are also many cool antennas, including a 15 meter quad set up by a bunch of Southern California teenagers. 

Near the end, when they visit ARRL Headquarters, we briefly see none-other-than Doug DeMaw, W1FB!  FB!  

Please take a look at this video and post comments about the rigs, antennas, and radio amateurs that you see in the film. 

Apollo 11 in Real Time

https://apolloinrealtime.org/11/

This web site presents all the data received from Apollo 11.   They are presenting it in the sequence it happened, exactly as it was 53 years ago today.  Today's clock is synched with clock from 53 years ago. I just tuned in today -- they are at the 6 day point in the mission.  Armstrong and Aldrin are on the Lunar surface, resting.  Collins is in orbit, sleeping.   

This is exactly the kind of thing we need to have playing in the background as we build things in our shacks.  Thanks to Peter O'Connell VK2EMU for sending us this wonderful link.   https://apolloinrealtime.org/11/  

 

Putting a Real LC VFO in My Ceramic-Resonator, Direct Conversion 40 Meter Receiver. LC JOVO! (Video)

This is the DC receiver that I built back in 2017-2018. I had used a ceramic resonator in the VFO. That receiver was on the cover of SPRAT magazine. It may not have deserved the honor -- recently Dean KK4DAS and I discovered that the ceramic resonator VFO drifted rather badly. So Dean and I are now building real LC analog VFOs. This is kind of an aside to a Virginia Wireless Society -- Maker Group project. This video shows my receiver working yesterday on 40 using the VFO that was recently thrown together.

More details on the original project (that used the ceramic resonator) here: 

https://soldersmoke.blogspot.com/search/label/DC%20Receiver%20Build

 The VFO circuit comes largely from W1FB's Design Notebook page 36.  I followed most of the conventional tribal wisdom on VFOs:  NP0 caps, often many of them in parallel.  Air core coil (in my case wound on a cardboard coat hanger tube). 

For C1 I used a big variable cap (with anti-backlash gears) that Pete N6QW advised me to buy on e-bay. Thanks Pete.   L1 is on the cardboard tube.  I only built the oscillator and the buffer -- I did not need the Q3 amplifier.  (The water stain in the upper left is the result of a heavy rain in the Azores around 2002 -- water came pouting into the shack.)  

I think the VFO is more stable than the Ceramic Resonator circuit. But I want to go back and give the ceramic resonator circuit another chance...  Miguel PY2OHH has some really interesting ceramic resonator circuits on his site. Scroll down for the English translation: https://www.qsl.net/py2ohh/trx/vxo40e80/vxo40e80.htm

Dean KK4DAS commented that VFO construction is as much an art as a science.  I agree -- there is a lot of cut and try, a lot of fitting the components you have on hand into the device you want to end up with.  You have move both the frequency of the VFO AND the tuning range of the VFO.  Mechanics (in the form of reduction drives) is often involved.  And, of course you have to apply lots of tribal knowledge to get the thing stable. You could, of course, avoid all of this by using an Si5351, but I think that moves you away from the physics of the device, and is just less satisfying. 

So,  JOVO!  LC JOVO!  The Joy of VARIABLE Oscillation!   

Hex DX! First Long-Haul Contact with the New Hex Beam - VK4KA on 20 SSB

This morning at around 1345 UTC I had the chance to try out my new Hex beam on some "down under" DX.  9,548 miles, 15,222 km    The DX Spot page told me that VK4KA was on 14.255 MHz.  QRZ.com said the beam heading for me was 270 degrees.   He was quite strong.  He was working a fairly huge pileup, going through callsign numbers.  He was on the 6s when I tuned in, so I had some time to test the Hex beam.  Above you can see a rough front-to-back test.  Below you can see a comparison with my old 75 meter doublet.  

A few minutes after the second video, in spite of the pileup I called VK4KA and made the contact.  I congratulated him on his homebrew Moxon.  https://www.qrz.com/db/VK4KA

It was fun to reach Australia with the new antenna. 

Jean Shepherd and Studs Terkel Talk About Radio on "The Big Broadcast" Sunday night 7pm-11pm

 

I'm home recovering from the second COVID vaccine booster (I feel OK, just a bit tired).  Our local public broadcast station, WAMU, announced that on Sunday night (July 17) from 9 to 11 pm EDST they will rebroadcast a 1962 radio show featuring Jean Shepherd and Studs Terkel.  They will be talking about the impact of radio on society.   

Here is the link:   https://wamu.org/show/the-big-broadcast/

Looks like they will make an mp3 available after the show.  

I like "The Big Broadcast" and often tune in.  

James Webb Telescope's Deep Field -- What Would Be Behind A Grain of Sand Held at Arms Length. Click on the Picture

 NASA’s James Webb Space Telescope has produced the deepest and sharpest infrared image of the distant universe to date. Known as Webb’s First Deep Field, this image of galaxy cluster SMACS 0723 is overflowing with detail.

Thousands of galaxies – including the faintest objects ever observed in the infrared – have appeared in Webb’s view for the first time. This slice of the vast universe is approximately the size of a grain of sand held at arm’s length by someone on the ground.

Hex Beam at N2CQR

 

I got my K4KIO Hex Beam up on the roof yesterday.  I think it looks pretty good!  It is in the same spot that I had my beloved Moxon.  Curse you Nor'Easter!   

Putting this thing in the air made me appreciate the relative simplicity of the Moxon.  It had just four poles, not six.  It weighed just nine pounds, not 25.  It was significantly smaller.  On the other hand, that antenna just gave me one band -- I have 20, 17 and 12 on this one, and I could add three more. Also, this one is a lot more rugged, and is likely to survive the next Nor'Easter. 

It was fun spinning it around.  First QSO was DX on 20 SSB:  EA1HDZ.  This morning I spoke to KP3CQ in Puerto Rico.  Later,  I was listening to ZS3Y -- he was faint until I tried him on long-path.  He was transmitting on the long path and was much stronger when I pointed in that direction.  

I kept the 75 meter doublet -- I just put it on another tripod.  So I will be able to continue to use that antenna for 40 meter AM contacts (I've been having a lot of those lately).   

Surface-Mount Solder Smoke -- Is THIS Really Homebrew?

I was recently noting that the assembly of IC, CPU-based projects doesn't seem like real homebrew radio.  I realize that there is a danger here -- there is a tendency in ham radio to reject the new and to stick with the old.  "SPARK FOREVER" was the rallying cry when CW came along.  There are still a lot of AMers who refer to SSB as "Single Slop Bucket." So, with that in mind I point the blog to the above video.    He is using complicated ICs that probably have thousands if not millions of transistors.  But he is definitely making something new. And he releases some real solder smoke in the process.   FB.  

It is probably not for me, but others may like it. Like the old song says "Different strokes for different folks." YMMV.   

A Truly Great Book: "From Atoms to Amperes" by F.A. Wilson (Free Download)

 

This is a really wonderful book.  I'm glad worldradiohistory.com has found a way to make it available as a free download.  This is the kind of book that you want to download and keep available for future study.  The day will come, for example, when you will want to understand how Einstein's special relativity explains how that transformer in your rig actually works.  F.A. Wilson explains that, and much more. Here is the link:  

https://worldradiohistory.com/UK/Bernards-And-Babani/Bernards/BP254-From-Atoms-To-Amperes-Wilson-1989.pdfoke.com

Thanks to Joefish for the heads-up. 

Would this Really Be Homebrew?

 

Hack-A-Day has an interesting post about an FM Broadcast radio project.  I took a look.  The Github page has the schematics for the hardware.  For me, the thing is, there is just not a lot there.  It is a bunch of chips.  The FM Tuner IC is the heart of the project.  With that one you have to dig down to see that it is a digital processing chip:

https://www.lcsc.com/product-detail/RF-Transceiver-ICs_RDA-Microelectronics-RDA5807MP_C167245.html

All of the action -- all of the magic of radio -- is locked inside those little SMD chips.  I suppose if you were skilled enough to write the software or to significantly modify it,  you'd get closer to the experience of homebrew radio,  but very few of us have those kinds of skills -- we just download the software, then struggle to get it into the chips. 

And sure, you could struggle to solder those chips to a PC board, but really, why bother when 99% of the components are already inside the chips?  You should just buy a board with the chips on them and with the software already loaded.  There you have it:  the store-bought appliance is really, really close to the supposedly homebrew receiver. 

But hey, to each his own.  This is a hobby and it is all for fun.  I just think I have more fun with old-style, analog, discrete component HDRs.  YMMV.     

Ciprian Got His Ticket: YO6DXE (and Romanian Mighty Mite FIXED!)

Ciprian writes: 

Thank you so much to you all... and thank you SolderSmoke for always writing about my learning in homebrew gear. I did finally got my license... just waiting for the paperwork to arrive. But now I'm finally YO6DXE ( DX Explorer lol ). I did found my issue with the power... it seems that it's from the cheap BD139 that doesn't seem to work as expected. I get about 500mW with a 2n2222. So I ended up making another version of the transmitter that I'm really happy about. 73 to you all DE YO6DXE.

SolderSmoke posts about Ciprian: https://soldersmoke.blogspot.com/search?q=Ciprian

Ciprian's QRZ.com page: https://www.qrz.com/db/YO6DXE

Ciprian's blog:  https://dxexplorer.com/

Ciprian's YouTube channel:  https://www.youtube.com/c/DXExplorer

Homebrew Variable Capacitors -- VU2NIL's Antenna Tuner (and other projects from Basanta)

 

OM Basanta VU2NIL  built a very nice antenna tuner using homebrew variable capacitors (above).  After seeing this, I feel unworthy -- I used FACTORY-MADE variable capacitors. I feel like such an appliance operator.  I hang my head in shame.  

Details on Basanta's tuner are here: https://www.qsl.net/vu2nil/projects/20210/20210.html

More project from him here: https://www.qsl.net/vu2nil/

And more here (his blog): https://vu2nil.blogspot.com/

Basanta has obviously made great contributions to the radio art.  Thanks Basanta.  And thanks to Alain F4IET for alerting me to Basanta's work. 

A Double Sideband Transmitter from France -- F4IET's "Master Robert"

The Radio Gods seem to be steering us toward Double Sideband.  A few days ago I got an e-mail from Alain F4IET.   We had him on the SolderSmoke blog two years ago, talking about his French backyard pandemic Field Day.  His recent e-mail reminded me of his very fine homebrew DSB transmitter, which is his only rig and with which he has worked the world. 

The rig is named for the fellow -- Robert F6EUZ -- who is Alain's teacher from the local radio club. 

Alain's rig was shown to the world in the G-QRP club's Winter 2020 issue of SPRAT (SPRAT 185).  Once again, let me note:  If you are not subscribing to SPRAT, you are just WRONG.  Join G-QRP and start receiving SPRAT:  http://www.gqrp.com/join.htm

Alain gives some nice shout-outs to Pete N6QW,  Charlie ZL2CTM, and Basanta VU2NIL, all of whom provided advice and counsel on this project.  So think about it:  the Master Robert rig was built in France under the guidance of a French Elmer, with advice from hams in the U.S., New Zealand, and India, and was featured in journal of the British QRP club.  That, my friends is the International Brotherhood at its best. 

As I read about Alain's rig, I found myself thinking about the Direct Conversion receiver projects underway around the world.   The Vienna Wireless Society's Maker Group, is, for example, building a simple DC receiver.   It would be relatively easy to pair up a rig like the Master Robert with a DC receiver (the VFO could be the only stage common to both transmit and receive) to make a simple phone transceiver.  That kind of rig was my first phone transceiver.  Alain reports that he is currently working on a second version of the Master Robert.  It will be a transmitter-receiver (TRX) and will be used in SOTA operations. 

Alain's description of his transmitter is a lot of fun: http://www.f4iet.fr/mdwiki/#!master_robert.md

I especially liked his comment about how the other phone stations never knew he was on DSB: http://www.f4iet.fr/mdwiki/#!dsb.md I had similar experiences out in the Azores with my DSB rigs.  

Here is Alain's main page: http://www.f4iet.fr/mdwiki/#!index.md

Alain's QRZ.com page:  https://www.qrz.com/db/F4IET

Here is the Master Robert schematic from GQRP: http://www.gqrp.com/Maestro_Robert_Cct.pdf

 

Here is a link to the 76 DSB posts on the SolderSmoke blog (keep scrolling down!): 

https://soldersmoke.blogspot.com/search/label/DSB

Details on Pete N6QW's Wireless Set

Details on this wonderful project:  https://www.n6qw.com/Wireless.html

Pete's blog post: http://n6qw.blogspot.com/2022/06/what-is-wireless-set.html

SolderSmoke blog link to video:

https://soldersmoke.blogspot.com/2022/06/pete-n6qws-hybrid-wireless-set-think-of.html

Flip-up Workbench Build -- Possible Application for Our Test Gear

Interesting workbench build.   While his tools were all for woodworking, this got me wondering about using this technique to store bigger pieces of electronic test gear that are not in use every day.  

 

Pete N6QW's Hybrid Wireless Set -- A Thing of Beauty, with Thermatrons

Pete Juliano is amazing.  He is admirably carrying a very heavy load of family responsibilities.  But  he still can build some really unique and innovative rigs.  He tells us that getting up at 3 am and only sleeping 5 hours per night allows him to do this.

Pete also blames Grayson Evans KJ7UM for this rig, what with the thrematrons and all.  Pete has a 7360 mixer in this rig, something that Grayson had in the 3rd edition of his Hollow-State Design book (get yours here:  https://www.ermag.com/product/hollow-state-design-2nd-edition/).  Pete reports that he first built the chassis for the tube (I mean thermatron) portion of the rig in the 1970s -- it has been in his junkbox ever since.  Grayson admires Pete's compact construction and point-to-point wiring.  

I too noticed very poor conditions on Field Day this year.  

Three cheers for Pete Juliano!  

Thoughts on Homebrew, Makers, DIY, and Hams -- from Lex PH2LB

Sometimes we get a comment that is so good that we elevate it to the main blog page.  That was the case with Lex PH2LB's comment on the blog post of Owen Duffy (yesterday). 

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When I started the hobby, it arose out of technological curiosity, the interest in understanding things and the will to make things myself (designing myself was not my main goal). It doesn't matter to me whether it is 100% DIY or a kit (such as Heathkit, Elecraft, QRP-Labs etc) which is modified or not after construction. Just having fun with the hobby and pushing boundaries. And yes I also have some off-the-shelf transceivers (I'm super happy with my FT817ND) and my QO-100 uplink is also a kit (which is then already soldered a little more than average). As far as new tools are concerned: here at home are 2 types of 3D printers, various tools for SMT assembly, and I have a nice workshop equipped with tools and equipment for metal / plastic / wood processing. And every day I try to learn something new, because I stand by the IBEW moto : If you know stuff, you can do stuff.

Am I a maker then? I wouldn't call myself that. Just like I don't call myself a hacker because I'm quite handy with computers, technology and have certain skills. I'm just a hobbyist who wants to do and make things after work.

---------------------

Lex is a true member of the International Brotherhood.  He is the one who took our beloved stickers onto the European continent and into a Netherlands pub.  He is the one who -- unforgettably -- saw the parallels between ham shacks and the "pleasure room" of "50 Shades of Gray" (See below -- apropos of his current message, we labeled his meme "50 Shades of Homebrew") For more on Lex see: https://soldersmoke.blogspot.com/search?q=PH2LB

Lex's web site (Shack on the Internet):  https://www.ph2lb.nl/blog/index.php?page=hamradio

 Thanks Lex! 

ZL2BMI Double Sideband QRP Transmitter in SPRAT #191

Very cool that SPRAT had a Double Sideband (DSB)  transmitter article in its current issue (#191 Summer 2022). The author is DSB guru Eric Sears ZL2BMI,creator of the famous ZL2BMI  DSB QRP transceiver. 

I think DSB is a great way to break into homebrewing for phone.  Building a DSB transmitter is a LOT easier than building an SSB rig.  The DSB transmitter can then be converted into a DSB/Direct Conversion transceiver.   

Here is a link to 75 SolderSmoke blog posts about DSB (keep on scrolling, keep on hitting the "older posts" button): https://soldersmoke.blogspot.com/search/label/DSB

Here are a bunch of blog posts that mention ZL2BMI: https://soldersmoke.blogspot.com/search?q=ZL2BMI

Thank you Eric, and thanks to G-QRP. 

Australian Homebrew: Owen Duffy ex VK1OD now VK2OMD. Are Hams Makers?

This week I stumbled upon this amazing blog from Australia.  I had to check with Australian friends to find out more about the author.  Owen Duffy has for many years been a rigorous homebrewer who has documented his findings on his blog:  https://owenduffy.net/blog/

For example, Owen asks the question, "Are hams makers?" https://owenduffy.net/blog/?p=122

There is a lot of great material on this blog.  It goes back to 2013.  Peter Parker notes that an earlier version of the blog (before Owen was forced to change his callsign from VK1OD to VK2OMD) goes back even further and is accessible via the Way-Back Machine:  https://web.archive.org/web/*/vk1od.net

Check it out.  Lots of really useful and interesting material there.   Thanks Owen.  And thanks to the Australian friends who provided background info. 

W8ZAP on 40 AM with a Collins 20V3 Broadcast Transmitter

 

I was on 40 AM yesterday morning and I talked to Jerry W8ZAP (great callsign) out in Michigan.  Jerry was running his Collins 20V3 (above on the right), which was originally an AM broadcast band transmitter.  FB.  

Here is Jerry's QRZ.com page: https://www.qrz.com/db/W8ZAP

More info on the 20V3: https://collinsaerospacemuseum.org/products/product_sheets/20V-3%20AM%20Transmitter%20Product%20Sheet.pdf 

WIRED on the Dangers of another Carrington Event, Solar Cycle 25, Capacitors Could Save Us All

This Wired article has some really interesting info on competing theories about the solar cycle, about the danger to the Earth from solar flares, and about what a flare like that of the Carrington event could do to the transformers we are currently using.  The article points out that large capacitors could protect these transformers from the effects of the flare.  But the power companies are not installing the capacitors. 

I think one of the scientists Pete mentioned in SolderSmoke podcast #238 is mentioned here: 

https://www.wired.com/story/sun-storm-end-civilization/?redirectURL=https://www.wired.com/story/sun-storm-end-civilization/