Author: William Meara

G0UPL at Dayton: SSB for the QMX, and Thoughts on Homebrewing

Click on the diagram for a better view.
Listen to the interview here:

http://soldersmoke.com/G0UPL at Dayton 2025.mp3

I think this is what Grayson was talking about when he said that Hans is a genius, and that his SSB project for the QMX was very complicated. On his website Hans says as much: “This is a very complex project.” Indeed it is. Just take a look at the bloc diagram above. This is not for the faint of heart. In this interview, he talks about a full year of intense work on SSB for the QMX. Wow.

I think Hans makes some good points on why we still homebrew. I liked his fish analogy: we can buy all the fish we want at the supermarket, but people still go fishing. Why? Because they like fishing.

I’m not too sure about “the IKEA effect.” He seems to be saying that people derive homebrew-like satisfaction from assembling IKEA furniture. Well, maybe some people do, but I think this is a long way from what we would consider true scratch-built homebrew. Dean KK4DAS, for example, recently observed that he assembled two IKEA tables, but that this assembly does NOT make him a carpenter. This is related to our discussion about the differences between ham radio kits and true homebrew: IKEA flat packs are like the kits. I think Hans is right about the pride and satisfaction that people get from building their own radio gear.

Thanks to Hans GOUPL and to Bob W8SX for doing this interview.

Mitch NK3H’s FB SolderSmoke Direct Conversion Receiver — “Incredibly satisfying!”

Wow, Mitch NK3H has built a really nice receiver. (He says it is not pretty, but those of us who have built one or who are in the process know that it looks great.) The SSB really sounds good also.

Mitch writes:

It’s not pretty but it works! Incredibly satisfying. In answer to the questions, (1) though I ‘d built a few small Manhattan style boards (e.g., Michigan Mighty Mite) this was more complicated. I’ve been using W1REX’s island cutter to create isolated areas on the copper clad board, rather than pasting on pieces of circuit board. But the islands are a little small for as many as four connections on one island, as in most of the transistor bases. Inevitably a component lead would inadvertently contact the ground plane and all bets were off. Tracking down the shorts was challenging. (2) Once I got to the audio amplifier board I carefully laid out all of the components before starting to solder. But as I finished each stage and was ready for the next, I always seemed to be missing a resistor or two. I’d search the desk and the floor — very frustrating. Turns out the speaker magnet was collecting and hiding the missing resistors. Lesson learned. (3) Next I’m hoping to build a transceiver. Still looking for the right project, probably a little more digital than this wonderful DCR.

Mitch obviously learned a lot during this project. I had similar experiences with pads on the same level as the surrounding board — I found that the 1 or 2 mm of elevation provided by the Manhattan pads prevented a lot of inadvertent shorts to ground. And I too “lost” (temporarily) a lot of components to the magnet in the speaker.

Good luck with the next projects Mitch. With the Michigan Mighty Mite and the DCR under your belt you are ready to go. Maybe a Double Sideband transmitter to go with the DCR? Or, as you said, perhaps something more digital. There is a lot of good ham experience with the Si5351 digital VFOs. Or maybe even an SDR rig.

Thanks Mitch. Congratulations and welcome to the Hall of Fame.

———————–

Join the discussion – SolderSmoke Discord Server:

https://discord.gg/Fu6B7yGxx2

Documentation on Hackaday:

https://hackaday.io/project/190327-high-schoolers-build-a-radio-receiver

SolderSmoke YouTube channel:

Grayson Evans KJ7UM Interview at Four Days in May at the Dayton Hamvention 2025

LISTEN TO THE INTERVIEW HERE:


http://soldersmoke.com/KJ7UM at Dayton 2025.mp3
Grayson said quite a lot in this short 4 minute interview:

— At FDIM he was selling his wonderful book “Hollow State Design for the Radio Amateur.” Buy one here: https://www.ermag.com/product-category/books/

— Grayson was also selling a Thermatron version of our beloved Michigan Mighty Mite transmitter. It is crystal controlled for the 40 meter band, but the Color Burst Liberation Army approves! Here is a wonderful video on this rig:
https://soldersmoke.blogspot.com/2024/09/excellent-new-video-from-grayson-kj7um.html
And be sure to watch Grayson’s excellent course on Thermatron Homebrewing:
https://soldersmoke.blogspot.com/2024/02/grayson-evans-kj7um-video-on.html

— Asked why someone should build with tubes when so much good solid state stuff is available, Grayson makes some especially excellent points: The solid state gear is often filled with mysterious little black boxes — we often don’t really know what goes on in there. Thermatron construction provides a break from complicated SDR nonsense “that is not really radio.” That last comment will generate some criticism, but not from here. I think Grayson is right, He earlier expressed admiration for complex circuitry, but he also rightly defends simple, understandable rigs.

Here are Grayson’s Technical Documents (a real treasure trove): https://kj7um.wordpress.com/

Three cheers for Grayson. And thanks to Bob Crane W8SX for doing this interview.

Bill K7WXW’s FB SolderSmoke Direct Conversion Receiver

This is a very nice build. Bill K7WXW fought a long battle to get this receiver working, and — more importantly — to understand why it is working.

Bill writes:

  1. The cycle of design, sim, build, debug, update, repeat can teach you a lot.


FB Bill. Welcome to the Hall of Fame!

Join the discussion – SolderSmoke Discord Server:

https://discord.gg/Fu6B7yGxx2

Documentation on Hackaday:

https://hackaday.io/project/190327-high-schoolers-build-a-radio-receiver

SolderSmoke YouTube channel:

Hall of Fame: The SolderSmoke Direct Conversion Receiver — 80 Completed Receivers, 7 Honorable Mentions, Built in 15 Countries — Many More Receivers Being Built.

WA1MAC’s Receiver

Please let us know if you spot any errors, or if we have inadvertently missed anyone. Don’t worry about being late to the game — the challenge continues. All of the info is still available (see below).

As of June 18, 2025 1049Z:


So far 80 completed receivers, with 7 honorable mentions. Receivers built in 15 countries.


NE3U (KY4EOD) Matt
KQ4AOP First ham signals ever heard!
N9TD Derek
AC3NG Ryan
VK3TPM Peter Marks
W4KAC Ken
W4KAC Ken built a second one!
N2EPE Erik
VA3NCA Wayde
KI5SRY Mark — Gears on PTO screw
KA1MUQ Frying pan receiver
AA1N Adam
ZL1AUN Aaron — Using SSB transmitter
W8UC Never before homebrewed.
VK4PG Phil — Nice case, “really pleased”
G7LQX Working well, video of CW and SSB.
KE2AMP John Spring on PTO screw — great
N9SZ Steve nice receiver
KD9NHZ Piotr Nice one
KE8ICE Calvin, Very cool receiver.
WV3V Jayson! Got it done!
GM5JDG Martin.
KF8BOG Jim: A long struggle, but success.
Chris Wales Fantastic video.
YD9BAX Wayan! Homebrew transformer!
N0NQD Jeff
WN3F Roy — Made new stickers!

AB5XQ Bill
KB7ZUT Andy
AA1OF Jer

VictorKees Holland
KC9OJV John — Manhattan-style convert
WZ5M 1, 2 or maybe even 3 receivers!
K1KJW Jim in Vermont
KC5DI Dallas — friend of WZ5M
Gary Australian — Wooden PTO form
LU2VJM Juan in Argentina
K1OA Scott “Most fun in 50 years”
KC9DLM Ben — Had EFHW problems
PH2LB Lex Yellow, Glue Stick
AI6WR David
G6GEV Dave (It was a blast!)
KC1ONM Wayne MakerLabs NH
KB1OIQ Andy MakerLabs NH
KA1PQK Jay MakerLabs NH
W1TKO Mike MakerLabs NH
K5KHK Karl
SM0TPW Mikael
KI7LKB Brian (coat hanger tube)
M6CRD Chris
W2DAB Dave in NYC
W4JYK Wes of VWS
KA4CDN Mike of VWS
M7EFO Adrian
VK5RC Rob
KD8KHP Dave
VK1CHW Chris
KA0PHJ Brian
W0IT Louis
W1PJE Phil
W2AEW Alan
KN6FVK John (Barkhausen-Be-Gone Spray)
VU2JXN Ramakrishnan
AA0MS Doug
9V1/KM7ABZ Paul in Singapore
VK2BLQ Stephen
N3FJZ Rick
Daniel VE5DLD
Student 1 Student of VE5DLD
Student 2 Student of VE5DLD

Student 3 Student of VE5DLD
K7WXW Bill
NK3H Mitch
KN4ZXG Ted
WA1MAC Paul
N4AVC Chuck
K3IY Kevin
N6ASD Ashish in Bangalore
W1DSP Rick
WD4CFN Steve

————————-
Honorable Mentions:


*AA7U Steve No PTO
*VK7IAN Ian — No Manhattan boards
*KC1FSZ Bruce’s build on a PC board
*CT7AXD Graham — different AF amp
* DL1AJG Andreas
* Matthew Student of DL1AJG
* Arash Student of DL1AJG
—————————————–

Candidates for the Hall of Fame:
SA5RJS Rasmus
KA9TII James
AA7FO Chuck
VA3ZOT Tony Surface Mount — Honorable Mention?
KM5Z Mike Yancey
AB2XT John (Done, just need the video)
KO7M Jeff (Piper Cub)
KD4PBJ Chris
VU2TUM Puneit Singh

For more information on how you too can build the receiver:


Join the discussion – SolderSmoke Discord Server:

https://discord.gg/Fu6B7yGxx2

Documentation on Hackaday:

https://hackaday.io/project/190327-high-schoolers-build-a-radio-receiver

SolderSmoke YouTube channel:

Daniel VE5DLD’s FOUR FB Saskatchewan SolderSmoke Direct Conversion Receivers

Daniel VE5DLD is a teacher in Regina, Saskatchewan, Canada. Back in early 2023 several lucky students joined him in building the SolderSmoke Direct Conversion receiver. We had asked people to build the receiver — we wanted to test the design before asking the local high school students to build it. Daniel and his students came through for us, and ended up having far more success than we did. Congratulations Daniel! Welcome to the Hall of Fame.

Daniel wrote:

Hi Bill! Yes, I had my own DC Receiver that I use every so often for fun and 3 built by my students. All working. We didn’t get any video because we just finished the school year and the kids left, but I’ve kept in contact with them and they told me they have been able to receive signals from their homes. The kids developed excellent troubleshooting skills gained large amounts of confidence in their ability to fix things. Over the next year, my students told about fixing their gaming consoles and fixing problems in their parent’s electronics. They are certainly no longer afraid of opening something up to see what is going on! And that’s what makes me the most happy! Yeah, you can just recognize myself and only mention that 3 students were able to build DC receivers.

And yes, the Michigan Mighty Mite was a fantastic gateway to home brewing!

Thanks for thinking of me and my students!

73
Daniel D.
VE5DLD

On June 19, 2023, Daniel wrote:

We got everything going and all 3 students now have receivers capable of inhaling RF. We 3D printed some knobs and hot glued them. We took one outside but didn’t hear any signals. Mid afternoon is not good for 40m. We will try again later this week and I’ll bring my KX3 to make sure there is a single for them to listen. This issue on that last radio was an improperly installed J310. The angle is was installed hid the problem well! Here are a few pictures of the completed rigs.

Back in 2015, Daniel built a Michigan Mighty Mite. I was pleased to be reminded that I had sent him the crystal. Go CBLA! For more info on Daniel’s transmitter see:
https://soldersmoke.blogspot.com/2015/10/saskatchewan-mighty-mite-video.html
Thanks Daniel! 73
___________________________

Join the discussion – SolderSmoke Discord Server:

https://discord.gg/Fu6B7yGxx2

Documentation on Hackaday:

https://hackaday.io/project/190327-high-schoolers-build-a-radio-receiver

SolderSmoke YouTube channel:

Honorable Mention: Andreas DL1AJG’s THREE SolderSmoke Direct Conversion Receivers for Biologists

Andreas DL1AJG was another of those intrepid hams who, in the dark of winter 2023 took up the SolderSmoke Direct Conversion Receiver Challenge in order to test our receiver (before we pushed high school kids to build it). Andreas came to the task with a lot of useful teaching experience. At the time he was an academic biologist and had been teaching a course called “Applied Electronics for Biologists.” See:

https://soldersmoke.blogspot.com/2022/08/can-biologist-fix-radio.html

Some of Andreas’s students

I put these receivers in the “Honorable Mention” category only because they deviated a bit from the basic schematic: they used an indoor ferrite antenna, had an RF amplifier ahead of the mixer, and did not use a transformer in the AF amp. But they are very clearly the SolderSmoke DC receiver, they succeeded in inhaling RF, and Andreas and his students built them to help us.

Here is the schematic they used:

Click on the image for a better view
Here is an e-mail exchange I had with Andreas when the scholatic dust had settled in June 2023:

Dear Bill,

Please my apologies for my late update on our DCR project. We started with the course in the semester break and once the semester started only a handful of students were able to finish their receiver. A long shelf of shame ….

Here is what we’ve got so far (those were finished at the end of April already). 3 nice DCRs completely sufficient to copy CW indoors without additional antennas starting from late afternoon. Strong stations can be heard all day. I found that coupling some 6m of wire with one or two windings to the ferrite core can boost the signal dramatically but can also increase noise.

The PTO is based on your design (Bill Meara N26QR & Dean KK4DAS) which was sparked by Farhan (VU2ESE) , except that I’ve swapped the FET for a NPN. The input amplifier and antenna is from the JUMA active ferrite antenna by Matti Hohtola (OH7SV), the band pass filter is from Hans Summers (G0UPL), the mixer and the headphone amplifier is inspired by Pete Juliano (N6QW), you told me that the diplexer (as well as the whole DCR idea) is attributed to Wes Hayward (W7ZOI) and the perfect schematics of Rick Scott (N3FJZ) where crucial to get me started in the first place. I enjoy keeping track of original sources, as I would do in science. This shows that even little achievements are based on the ideas of many other great people – and this is nothing to be ashamed of.

This was a lot of fun! Thank You!
Best and yours sincerely,
Andreas

Wow, the direct conversion re-engineering of education continues, this time at graduate-school level with biologists in Munich! Amazing.

Andreas points out that his group was also plagued by semester-related problems that caused many additions to the German shelf of shame. Let’s hope that someday soon these builders will come to their senses and join the ranks of those who have finished their homebrew projects.

Looking at the schematic (above) of Andreas’s project, there are a couple of significant differences from ours:

— Their AF amp used a transformer-less push-pull design. We had considered this but abandoned it thinking that it would be too complicated to explain the workings of this circuit to our students.

— Most significant, is Andreas’s use of a ferrite rod antenna and an RF amplifier. I think a simple 33 foot quarter wave antenna (with a ground or a counterpoise) might work better. But hey, to each his own! The important thing is that a number of these receivers were successfully built. They look beautiful.

Congratulations to Andreas and the successful Munich homebrewers!

———————————–

Thanks to Andreas DL1AJG. Welcome to the Hall of Fame.

————————————

Join the discussion – SolderSmoke Discord Server:

https://discord.gg/Fu6B7yGxx2

Documentation on Hackaday:

https://hackaday.io/project/190327-high-schoolers-build-a-radio-receiver

SolderSmoke YouTube channel:

Rick N3FJZ’s Early Completion of the SolderSmoke Direct Conversion Receiver Challenge

It was a cold day in early February 2023. Rick N3FJZ had responded to an early version of the SolderSmoke Direct Conversion Challenge:

I wrote:

Rick N3FJZ has completed his the direct conversion receiver that we will soon be building with students at a local high school. See video above.


We are hoping that a number of people will build the receiver as we designed it. Some folks have sent us versions of the receiver that they have built, but these versions often include significant deviations from our design, rendering them less-than-useful in checking our work. Rick built it just as we prescribed. His build is very useful in confirming the validity of our design. So if you are working on one of these receivers, I would encourage you to — for the moment — dispense with innovations and build it the way Rick did: as per the design we have been using.

We know that our design is not perfect. But we have decided to stick with it because it is very simple and very easy to explain. Examples: We know there is an impedance mismatch between the mixer and the AF amp. But fixing this would introduce complexity that we want to avoid. And the receiver works fine with the imperfection. We know that a push-pull AF amp would probably work better than the one we have. But we do not want to have to explain push-pull amps, biasing schemes, and PNP transistors in this short introductory course. So we stuck with three common-emitter AF amp circuits and an 1K-8ohm transformer.

Rick did a really excellent job not only in building this receiver, but also in documenting it. His diagrams and drawings are really superb. We will probably use these in our presentations to the students:


We will keep all of you informed on the progress of this project. We will begin this week. But if you are still working on the receiver, please send us your work, even if it comes in after we begin the course.

Thanks Rick!

————————————-

Thanks indeed Rick. Sorry it took so long to put you in the SolderSmoke Challenge Hall of Fame, but you are in now, and you definitely deserve it. Congratulations OM.

I especially like your finding the audio ourput transformer in an old transistor radio. Too often we see builders quit after discovering that Mouser or some other supplier no longer stocks the needed part. You show that homebrewers have other sources available, if they are willing to scrounge a bit. FB. I also liked the switch that helped compare the outputs of the two AF transformers. Very useful.

Thanks too for all the great videos and your really nice documentation — we have used your work quite a lot.

73 and welcome to the Hall of Fame!

Rick N3FJZ
____________________________

Join the discussion – SolderSmoke Discord Server:

https://discord.gg/Fu6B7yGxx2

Documentation on Hackaday:

https://hackaday.io/project/190327-high-schoolers-build-a-radio-receiver

SolderSmoke YouTube channel:


Stephen VK2BLQ’s Very FB EARLY build of the SolderSmoke Direct Conversion Receiver

This was back in the old days, long before we had Discord. It was early 2023, and we were getting ready to start the Direct Conversion receiver project at the local high school. I put out a version of the SolderSmoke Challenge: I asked people to build our receiver and let us know if it worked for them. Stephen VK2BLQ took us up on this and built the beautiful receiver you see above.

Thanks Stephen. Welcome to the Hall of Fame!

Stephen wrote:

Bill,


Don’t worry, you are not alone out there.

Here is my build; sorry that the front panel is overexposed and hard to see, but it is plywood.

I did follow the schematic but due to the contents of the junk box there have been some component changes.

The only thing that I had to buy was the 3/16 x 50 mm (2 inch) brass screw.

My calculations for the coils for the PTO and BPF were a little bit off necessitating padding down the PTO with a further 100 pF (easier than remaking the coil and mounting) and removing a few turns from the T50-6 toroids.

Like other people have found: the audio takes off at full volume; I am thinking but not yet tried adding decoupling between R5 (15K) and C2(47 uF). It isn’t the actual values of the electros as I had to use 100 uF so might be the audio output getting back into the earlier stage.

The tuning range I get is our 7000 to 7200 KHz and some shortwave stations above and below, Turning the screw is a little bit fiddly, but once tuned the vfo is quite stable and the audio sounds good.

Best wishes,

Stephen

VK2BLQ

MIT’s Haystack Observatory and Dr. Herb Weiss

We are really privileged to have among us (and in the SolderSmoke Direct Conversion Hall of Fame) Phil Erickson W1PJE. Phil is the Director of the MIT Haystack Observatory.

Phil writes:


Hi Bill, Dean, and Pete,

I surfed over today to Soldersmoke and noticed you had put up a very nice film from the 1960s made by MIT “Science Reporter” on the DSKY design for the Apollo Guidance Computer.

In the same vein, you might enjoy viewing something from the same era on the Haystack 37m telescope / radar in its early mid 1960s days:

The video features Dr. Herb Weiss who is still with us at nearly 106 years old (he visited a couple years ago).


Herb built the observatory for its original ballistic missile radar / satellite imaging mission and was involved in early MIT microwave radar development.

“Growing up in Elizabeth, New Jersey, Herb liked gadgetry. As a teenager, he became a ham radio operator and built a primitive television set at the same time NBC was trying to get its first signal on the air. His shop teacher was so impressed by Herb’s genius that he contacted MIT, which invited Herb to attend the college.


He spent the bulk of his career developing radar when there was none in the United States. He joined the Radiation Lab at MIT, which was just being established to support the war effort during World War II, designing radars for ships and aircraft. In 1942, when England was in the throes of its air war with the Nazis, Herb went to England and installed radar in planes with a novel navigation system that he and a team had designed for the Royal Air Force. He later spent three years at the Los Alamos, New Mexico, laboratory improving instruments for the A-bomb. After seeing the need for a continental defense network against the Soviet missile threat, he returned to MIT to build it. If not for Herb, there also likely would be no MIT Haystack Observatory, a pioneering radio science and research facility.”


As you can see from above, Herb is also a ham:


“Weiss:


Okay. I was born in New Jersey, and my first acquaintance with electronics was about the age of 12 or 13. We had a battery-operated radio, which didn’t work, and I asked around about what do we do about it. They referred me to a man two blocks away, who was a radio ham it turned out. So I carried this monster with the big horn and, I guess, the dog sitting on the speaker to his house. We went down in the basement, and I was just fascinated. I was hooked right then and there. A year later I became a radio ham at the age of 13, 14 and literally have been in the field ever since, until I retired. I was fortunate enough to go to MIT as an undergraduate, and most of the people I ran into of that vintage didn’t really have a hands-on feeling for electronics. By the time I got to MIT, I had built all kinds of things, including a TV set. Then it turned out that NBC was just trying to get their TV set on the air in New York on top of the Empire State Building.”


https://ethw.org/Oral-History:Herbert_Weiss


Herb and his wife Ruth had another career after MIT as a wind power pioneer and he is still an avid sailor:


One of our inspirations, and it came from building ham radio sets as a youngster. Enjoy the history.

73
Phil W1PJE

—

—-
Phil Erickson

phil.erickson@gmail.com


————————————————-

I would really like to get more info on Herb’s homebrew TV receiver. His was significantly earlier than the one described by Jean Shepherd.

Thanks Phil! And thanks Herb!

Paul 9V1/KM7ABZ’s FB SINGAPORE SolderSmoke Direct Conversion Receiver

Wow, I had been feeling a bit discourged about the slow-down in receiver completions, then I woke up this morning and found this e-mail from Singapore. My faith in ham radio was restored. Welcome to the Hall of Fame Paul. You get extra credit for doing it from far-off and exotic Singapore.

Paul includes in his “proof of life” video not only some Malaysian SSB and some CW, but also some very close-by China Radio International. FB Paul.

I also liked the way Paul used the local library to burn the schematic of the receiver burned into the board upon which it was placed. And the library also 3D printed his PTO coil form.

And ET confirmed Proof of Life! FB!

Be sure to check out the really nice build description in Paul’s blog and Github page (links below):
Paul writes:

Hi Bill, Pete, and Dean,

I’ve finally made a “proof of life” video for you, plucking some CW, voice and shortwave signals from the 40 and 41m bands here in Singapore. What fun this was, and I am amazed at how well this works, even from the confines of my 15th floor apartment.


Thank you so much for laying down the challenge – it came at just the right time for me, rekindling my enthusiasm and electronics and radio. It even encouraged me to finally get my license – I’m newly minted general class KM7ABZ (yet to get a 9V1 conversion license for my home here in Singapore). I can honestly say that listening to the SolderSmoke and Ham Radio Workbench podcasts since 2018 or so was worth *at least* 50% on the exam… somehow I already knew a bunch of stuff by pure osmosis!

Everything went pretty smoothly with the build. The only real issue I had was adding some caps to tame persistent motor-boating in the audio amp. Other than that, the build follows the official SolderSmoke schematic and parts selections.

I used the laser cutters at our local library to cut and etch a custom base. The library is a great resource: it’s also where I printed the PTO former.

To get on the air from my apartment in Singapore, I’m using an MLA-30 Active Loop antenna, with a PLJ-1601 frequency counter attached to the PTO to take some of the guesswork out of tuning.


All the details of my build are published at https://leap.tardate.com/radio/soldersmokedcrx/ (from GitHub).


Cheers,
Paul
🎉KM7ABZ🎉 from 9V1 land

______________________________

Join the discussion – SolderSmoke Discord Server:

https://discord.gg/Fu6B7yGxx2

Documentation on Hackaday:

https://hackaday.io/project/190327-high-schoolers-build-a-radio-receiver

SolderSmoke YouTube channel:

WWII Homebrew In Norway

Go to amateurradio

•

How My Grandfather Tuned Into London During WWII with a Radio He Built in Secret

General

My grandfather was a lifelong radio enthusiast and ham radio operator. In his early twenties during World War II, he lived in the remote mountain village of Hjerkinn, working at the railroad station high above the treeline when Germany invaded Norway.

He joined the resistance movement and built radios using parts from a downed Luftwaffe aircraft—mainly the radio tube, as seen in the photos I’ve attached. With it, he secretly tuned into broadcasts from London. It was a risky and courageous act, but it kept him and others informed when access to truthful news was critical.

Later, he introduced me to the world of radio. As a kid, I spent hours scanning ham bands, police channels, and even unencrypted cellphone calls. I was probably way too young to be listening to some of it, but in the pre-smartphone era, it felt innocent enough. That early exposure sparked a lifelong passion for electronics and radio—one that still defines me today.

A few weeks ago, I visited my mom and saw one of the wartime radios he built. I thought this group might appreciate it—not just as a relic, but as a story of ingenuity, resistance, and the enduring magic of radio.


Thanks to Jim VE1KM for alerting us to steeljo’s story. I told Jim that that Nazi tube is reminder of just how dangerous this all was for his grandfather.

The Computer Hardware of the Apollo Program

Watching this, it seems like a miracle that we made it to the moon. Some of this construction is downright scary. Sometimes soldering is not good enough — so they weld. Other times they don’t even solder — they wire wrap! Even in 1965, the wiring of the memory modules was so complex that it was beyond human comprehension. All of this brought back memories of that wonderful book “Sunburst and Luminary” by Don Eyles. I have hopes that he will appear in the MIT video about landing on the moon. Don worked on those programs.

The Computer Hardware of the Apollo Program

Watching this, it seems like a miracle that we made it to the moon. Some of this construction is downright scary. Sometimes soldering is not good enough — so they weld. Other times they don’t even solder — they wire wrap! Even in 1965, the wiring of the memory modules was so complex that it was beyond human comprehension. All of this brought back memories of that wonderful book “Sunburst and Luminary” by Don Eyles. I have hopes that he will appear in the MIT video about landing on the moon. Don worked on those programs.

On the importance of taking a break.

Thomas K4SWL has a good post about the importance of taking a break from radio. Following up on this, I noted that “taking a break” is often a good way of finding a solution to a difficult problem. I noted that I have confirmed this — it has worked for me. Pete Juliano N6QW recently announced that he is taking a break from the MHST project. That is a good idea. A solution will likely emerge.

I noted that there is some evidence backing up our suspicion about the benefits of breaks. I earlier shared some comments from Harry Cliff’s excellent book, “How to make an Apple Pie from Scratch.”

https://soldersmoke.blogspot.com/2024/04/cloud-chamber-finale.html

Harry also wrote about the usefullness of taking breaks. In 1917 Ernest Rutherford was having trouble understanding the presence of some hydrogen nuclei. Harry writes:

“Again, he was forced to put his work on hiatus to go on a mission to the United States in the summer of 1917, but it turned out to be one of those useful breaks when stepping away from a problem lets your mind slowly work out the problem in the background. When Rutherford got back to the lab in September he had the answer…”

There are many other examples.

So, if you get stuck, take a break!

Peter Parker VK3YE finds a Homebrew Double Sideband Transceiver at an Australian Hamfest

Peter’s detective work on the mystery box starts at around 13 minutes into this video. He quickly found a balanced modulator and did not find a crystal filter. This led him to correctly suspect a double sideband transceiver. A look at the LP filter and the VFO led him to suspect a 160 meter rig. Nice work Peter. That’s what it is: a 160 meter DSB transceiver.

I had a similar experience with a direct conversion receiver, but never with a full double sideband transciever. Nice find. Peter should try to bring that rig back to life, and he should try to find out who built it.

The Solid State Basics book by DeMaw and Rusgrove looks good. I hadn’t seen that one, but I will get one.

Thanks Peter!

Doug AA0MS’s FB SolderSmoke Direct Conversion Receiver: “This project has been a hoot!”

Doug built a really beautiful receiver, but reception was marred by a bad hum. It was quickly determined that this was caused by a noisy “wall wart” located close by. A re-location of the power supply remedied that, and allowed Doug to pull in some really nice signals.


Doug writes:

Had a lot of fun doing this over the past couple of weeks. Not my first DC receiver build–I built a Neophyte Receiver from QST years ago–but this one was the most fun. Thanks Bill, Dean, and the whole DCR challenge community–I’m learning a lot in my old age!

I’m a retired pastor who’s been fiddling with radio stuff since about 1991, and though I’ve been inactive for long periods of time, I’ve always enjoyed QRP and homebrewing (and I’ve built a bunch of kits, too, including my main rig, an Elecraft K2). It’s been a while since I had a halfway decent antenna up, but that’s in the works. As a boy I was at my dad’s side in his modest shack whenever he was building or operating (he was K8LZO back in the day), and one day while listening to shortwave broadcasts during the first Gulf war, I tuned around and heard some CW signals and decided it was time to learn the code and get my license. Anyway, this project has been a hoot, and I so appreciate all of you and your generosity with your experiences and experiments and successes and failures. Thanks! 73, Doug, AA0MS

Congratulations Doug and welcome to the Hall of Fame.

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Join the discussion – SolderSmoke Discord Server:

https://discord.gg/Fu6B7yGxx2

Documentation on Hackaday:

https://hackaday.io/project/190327-high-schoolers-build-a-radio-receiver

SolderSmoke YouTube channel:


Ramakrishnan VU2JXN’s FB SolderSmoke Direct Conversion Receiver: “Extremely thrilled! Hooked!”

This is a really important Hall of Fame entry for us. This is our first completed SolderSmoke Direct Conversion Receiver from India (more will come).

Most importantly, this receiver was built by our good friend Ramakrishnan VU2JXN (ex VU3RDD). Ramakrishnan goes way back in SolderSmoke history. He was the one who first suggested (in 2006!) that our podcast needed a blog to go with it. This was the origin of the SolderSmoke Daily News. A short time later we announced the birth of Ramakrishnan’s daughter. That same daughter now has her ham license and will build a second receiver with her dad.

Ramakrishnan VU2JXN

The roots of this receiver are deep in India. When Dean and I first went to the local high school to talk about ham radio support, I carried with me a Direct Conversion Receiver inspired by Farhan VU2ESE. In fact, that receiver had a picture of Farhan and quotes from him taped to the wooden base. When Dean and I designed the receiver that we tried to build with the High School kids, we used an oscillator based on the DC receiver that Farhan was building with youngsters at Indian girl’s schools. That is the receiver design that we are using in this SolderSmoke Challenge.

Ramakrishnan is in Bangalore now, which is where he built this receiver. Ashish N6ASD is also there now, and is building a receiver.

Ramakrishnan writes:

This morning before I got ready to come to work, I got a few minutes
to turn on the radio and catch the morning nets. Extremely thrilled to
get this working. The PTO is very stable.

Needless to say, you folks convinced me to get back into homebrew
and you have hooked me into it with this project.

I am off to my ailing mother’s place tonight. I don’t have a station
there, but I am carrying a copyof EMRFD with me (I have two!).

I want to listen with this receiver as you all always say
and make simple modification to this receiver and improve it.

Again, couldn’t turn off from it even though I am at work! The bug has
caught me.

Here is some more video of Ramakrishnan’s receiver:


Congratulations Ramakrishnan. Welcome to the Hall of Fame!

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Join the discussion – SolderSmoke Discord Server:

https://discord.gg/Fu6B7yGxx2

Documentation on Hackaday:

https://hackaday.io/project/190327-high-schoolers-build-a-radio-receiver

SolderSmoke YouTube channel:

Wow! DOVAD and Doppler at White Sands Missile Range

EI7GL has a really interesting blog post about a VHF system used at White Sands to accurately track early rocket tests: https://ei7gl.blogspot.com/2025/05/369-mhz-doppler-radar-antenna-at-white.html

He has nice picture of the antenna. The plaque has the interesting info:

The plaque on display reads as follows…

“36.9 Megahertz Helix Antenna Doppler Velocity and Position (DOVAP)

Reference Transmitter Antenna

Developed during World War II by the Germans as part of a V-2 guidance and control system, DOVAP traced the course of a rocket using the Doppler Effect caused by a target moving relative to a ground transmitter and receiving stations.

Unlike radar, Dovap did not allow scientists to “see” the rocket on a screen. Instead, it sent up radio waves, which were received and rebroadcast back to earth by the rocket. The returned waves combined with the original ground broadcast and produced a musical tone which varied with the rocket’s speed – the faster the rocket, the higher the pitch.

DOVAP data was extremely accurate: it could place a rocket’s position at 100 miles up within 50 feet. It could collect data at the extreme altitudes of 100 to 300 miles. Dovap’s disadvantage was that it took 3 to 4 weeks to reduce the data.

The antenna is a helix because of its physical and electronic characteristics. A helix is simple to construct and operate, provides necessary signal gain and directivity, and can be operated in several modes or polarizations.

The DOVAP system provided trajectory data and ground guidance for most of the early rocket systems: Corporal, Sergeant, Honest John, Little John, Redstone, and Aerobee Upper Atmosphere programs.

This particular antenna was built in the mid-1960s near C Station. Like much of the early instrumentation used here, it was designed and built at White Sands Missile Range.

Erected by White Sands Missile Range Museum. (Marker Number 06.099.)”