Joe N90K's FB SolderSmoke Direct Conversion Receiver

Congratulations to Joe N9OK on his homebrew build of the SolderSmoke direct conversion receiver. Welcome to the Hall of Fame Joe.  

Joe makes some very nice comments on the benefits of doing this in a homebrew way:  

I've build many dozens kits over the years, esp Knight, Heath, K2, K3, and others. This was my first receiver built from scratch. It works surprisingly well and has decent sensitivity. Thanks @Bill N2CQR and Dean @Soldersmoke for creating this challenge. It was fun and non-trivial. The only stage I had issues with was the amplifier, which was too compact on v1. v2 works well.

I think Joe should hold onto that smaller version of the AF amp. I think he could get that stablized and it could become the heart of yet another FB DC RX.

Joe went the extra mile and measured the minimum discenable signal of the receiver:

 

I see no problem with Joe's measurment technique.  I think the key word here is "discernible."  Often people will focus on the RF signal that will produce a 3 db or 10 db increase in audio signal.  But Joe has just looked at the RF signal level that will create a discernible audio signal.  That is fine.  As Joe demonstrates, this simple DC receiver is remarkably sensitive.  

Fritz's FB SolderSmoke Direct Conversion Receiver

Fritz did an excellent job on his build of the SolderSmoke Direct Conversion receiver.  Fritz writes: 

Hi folks!  First-time radio builder here, and I've just completed my DCR build! (Pic and video below...)

I have a background in electronics, but mostly audio, digital, video games, tube guitar amps, etc.  My only previous experience with radio was a restoration of a small AA5-style radio for a friend.  I first saw this project featured on w2aew's site and it seemed too fun not to try.  First go with Manhattan construction, too, and I really enjoyed it!

Though I built everything on one board, I did test the modules one by one as I went.  I did build and test the audio amp "left to right" instead of the other way around, because I have enough bench gear that I could check as I went without relying on the speaker. 

My audio amp build did tend to motorboat turned about half-way up, particularly with no RF input.  It was easy to see on the 'scope that the DC power bus was the feedback path.  Threw a couple 470uF on there and that pretty well quenched it.  In addition to the coil former, I also 3d printed a battery clip and and bracket for the volume pot.

Tuning turned out to be pretty delicate/twitchy, but I am getting better at it.  I opted to start with the 28 TPI steel screw after reading some things on the blog.  I will probably end up moving some of the windings off the tuning former to try and improve this, and/or investigate a fine tuning option.

I am running right now with a 33' wire out my basement window, up the side of the house, and partway across my flat roof, plus a 16' counterpoise on the basement floor.  Will probably get more ambitious with a feedline to a vertical wire in a tall tree in the backyard away from the house this upcoming week.

No license or callsign yet, but I've definitely got the bug with this project, so am reading the materials and hope to take the exam(s) soon!

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

Congratulations Frtiz -- Welcome to the Hall of Fame! 

Dan KF5DAN's FB SolderSmoke Direct Conversion Receiver

It is a happy occassion whenever we get to announce a new member of the SolderSmoke Direct Conversion Receiver Hall of Fame.  And Dan KF5DAN has entered the hallowed halls.   Congratulations Dan.  We are really glad you are doing the happy dance.   Above you can see Dan's receiver inhaling SSB, in the video below you see it receiving CW. 

Dan writes: 

I would like to present proof of life! I found the motorboating issue in my amplifier. R18, 1K resistor was connected from the power rail to the base of Q5, instead of the collector. I moved it, and had already added a 470uF cap from earlier troubleshooting. There is a lot of noise, probably due to some stormy weather in Arkansas this evening. I'm doing the happy dance over here.

Thank you very much! I am very appreciative of all the guidance and suggestions everyone has provided. I am very happy to be in this group of hams and homebrewers.

Mike KM5Z's SolderSmoke Direct Conversion Receiver

Congratulations to Mike KM5Z on the completion of his SolderSmoke Direct Conversion Receiver. 

Welcome to the Hall of Fame. 

Mike writes: 

First time with 'Manhattan' style construction, although it worked perfectly and was very easy. In this video I just did a scan from about 7.100 to 7.210 MHz. As you can see, I took advantage of another ham's 3D prints.
After all, if an idea is worth doing, then... it's worth overdoing.I used a Milwaukee 1/4" Diamond Max hole saw to cut circles for the solder-points. Everything else is ground. Later, I found that I missed a point, so I used a single "MePAD" glued in that spot.I found the default audio amp to be a bit quiet. I plan to replace it with the 'push-pull' version.  I'm definitely keeping this to hang up on the wall.

Hall of Fame Update: 84 Completed SolderSmoke Direct Conversion Receivers, with 7 Honorable Mentions. More receivers are being built. As of July 27, 2025 1057Z

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 July 27, 2025  1057Z:

So far 84 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

KM5Z              Mike

KF5DAN         Dan

Fritz                 Fritz

N9OK               Joe

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

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? 

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:

https://www.youtube.com/@soldersmoke

Steve WD4CFN's FB Mid-Tennessee SolderSmoke Direct Conversion Receiver

 

Steve WD4CFN has built a FB SolderSmoke Direct Conversion Receiver.  CW reception video appears above. 

From his QRZ page:  "I also enjoy QRP.  A group of us have started a local QRP club this year, MidTN QRP Group. (https://groups.io/g/MidTNQRP). "

Steve writes:  

I finished my SS DCR tonight and connected an antenna. Lots of summer QRN, but also lots of signals. Thank you and Dean for all the work you guys put into this project.  It is so well done and documented.  The whole project has been a great learning experience, especially the mixer part.  I haven't built a diode ring mixer before, just used the SA602/SA612 type mixer.  Testing the mixer pushed me to better understand how to use the FFT function of my scope to make sure the mixer was working correctly.  This was a great project! Thanks to all.

Here is Steve's receiver inhaling SSB:

Congratulations Steve. Welcome to the Hall of Fame.

Rick W1DSP's FB SolderSmoke Direct Conversion Receiver -- Exploring the Rabbit Holes

Thanks to Rick W1DSP for sending us his "proof of life" video.  It is indeed alive!  Congratulations Rick!  Welcome to the Hall of Fame!

Rick writes: 

Here's another SS DCR proof of life video. I took a bunch of detours on the way to get here - redesigned the coil former to add a fixed coil (learned openscad), spent a bunch of times on the DCR classics (KK7B, W7EL designs), acquired parts to build the original KK7B DCR, and so on. This is the sort of project that's a perfect excuse to explore all the sorts of rabbit holes we hope to find along the way to completing a project. Thanks for a great project. I'd just like to add that you're building a great community of experimenters. Most excellent, sir! Thanks to Bill & Dean!

Ashish N6ASD's Beautiful SolderSmoke Direct Conversion Receiver -- Built in Bangalore -- "This was such a fun project. This was my first direct conversion build, and I learned a lot along the way."

Ashish N6ASD is a really good guy.  We started watching his projects when he was in San Francisco.  He does a lot of fundamental radio building.  And he is a friend of Homebrew Hero Frank Harris K0IYE. 

When I spotted a "thumbs up" from an N6ASD on the SolderSmoke Discord channel, I knew that we would soon have yet another Bangalore Direct Conversion Receiver.  Ashish has been in contact with both Farhan and Ramakrishnan.  FB. 

Ashish writes:  I finally finished building the receiver! This was such a fun project. This was my first direct conversion build, and I learned a lot along the way. The biggest challenge was finding stable capacitors for the oscillator. In my first attempt, I used whatever I had in my junk box, but those capacitors drifted all over the place. Mica caps seemed expensive and difficult to get in Bangalore. I ended up buying surface-mount NP0 capacitors instead. Soldering them was a hassle, but they are much cheaper and easier to get here. Next step will be more mods and experimentation! The first improvement will be in the BPF. I will replace the regular ceramic caps with NP0 caps and re-tune it.

Here is Ashish's receiver inhaling CW:   

Congratulations Ashish -- Welcome to the Hall of Fame! 

Ashish N6ASD

The resemblance between Ashih's photo and the famous

1818 painting by Caspar David Friedrich is completely coincidental,  

but quite remarkable. 

https://en.wikipedia.org/wiki/Wanderer_above_the_Sea_of_Fog

 

Kevin K3IY's Beautiful FB SolderSmoke Direct Conversion Receiver: "An amazing experience... A milestone for me..."

Kevin's receiver was beautifully built. And it sounds great.  Congratulations Kevin, and welcome to the Hall of Fame. 

Kevin writes: 

This was my first “real” homebrew project.  I’ve built a few kits and toyed with some basic circuits, but this is a milestone for me.  It wasn’t without some troubles but what an amazing experience.  I couldn’t get my oscillator to work and the issue was I tried to make due with two 680pF ceramic caps.  I took Dean’s advice to stick with the 330pF silver mica’s and I found my signal.  At this point I also broke down and bought an oscilloscope.  I now plan to do some mod’s and eventually build a TR switch and pair it with a transmitter.  I can’t thank Bill and Dean enough for making this an obtainable goal.  Kevin, K3IY

Kevin's receiver on CW (above) and SSB (below). 

He's thinking about his receiver

Chuck N4AVC's FB SolderSmoke Direct Conversion Receiver: "I enjoyed the build and testing."

Chuck N4AVC's use of the frequency counter in his digital multimeter is pretty cool and innovative. And it is nice to have yet another receiver in Virginia; he is down in the Richmond area.  And of course the Sharpie callsign tattoos on the wooden board are really nice. 

Chuck writes:  

Completed!!! For Pete: "She ain't pretty, but she sure can cook!". Thanks Bill and Dean, I enjoyed the build and testing. It's funny, the audio oscillates on an older 9v battery, but is clean on the 9.5v bench supply. Going to put Bill's mod on the inductor to make tuning a little finer and spread the boards out a little more. I used the double sided boards I had and there is some interaction between the boards.

Congratulations Chuck! Welcome to the Hall of Fame!

Paul WA1MAC GETS DOWN TO BRASS TACKS with his FB GLUE STICK SolderSmoke Direct Conversion Receiver

 

Wow, look at that beautiful build of the SolderSmoke Direct Conversion Receiver.  We haven't received a "proof of life" video from Paul yet, but we trust that his receiver does in fact work.  Paul has some heavy care-giver responsibilities that keep him in his home.  We do not want to complicate  his life by asking for outside antennas or videos.  

We are also not going to complicate Paul's life my insisting that he build it our way.  First, his life is already complicated enough, and second, the innovations he introduced are really cool.  The use of brass tacks and conducive copper tape is really ingenious.  And the glue stick has brought him to the Joy of Oscillation (JOO).  In fact the glue stick has given him JOVO -- the Joy of Variable Oscillation.  FB Paul.  

Paul writes: 

Hi guys

I've been gettin down to brass tack here at the mac-shack!  Fits in nicely within my new caregiver role.

Been having a ball with the brass thumbtack breadboarding from SPRAT on your DC Receiver challenge!

Gluestick PTO, check, alive with the joy of oscillation!

BPF, check (need to tune once I find the nano VNA here somewhere)

DBM and diplexer, check, there was room on the board left over so I cheated and snuck the BPF on that board too

3 BJT audio amp with transformer, check, alive and passes the finger test, loudly!

Since I currently have no 40m antenna here guess it's time to finally put that active antenna I've been meaning to build............Any how thanks for all the fun and hair pulling, oh wait, I'm already bald!

 

73

 

Paul  WA1MAC, get it the mac-shack  :-)

JOVO! 

Glue Stick! 

Brass tacks! 

Congratulations Paul!  Welcome to the Hall of Fame!  

Ted KN4ZXG's FB SolderSmoke Direct Conversion receiver: "This project is the greatest gift to homebrewing..."

There it is, a thing of beauty.  The best part is that Ted built this receiver himself.  That is something that most hams NEVER do. 

Ted writes: 

This project is the greatest gift to homebrewing since I got interested in radio nearly a decade ago. Lot's of great projects out there but most go into a mysterious black hole of obsolete parts like the NE612 mixer that's hard to get, or even the LM386, which is plentiful but not as cool as this amp. Everything's divided neatly on it's own board and explained. The builder has wiggle room on the layout and ways to test each module whether that's with nice or budget equipment. Not only did I learn a ton about each stage, but also about making RF probes and making use of my modest but super useful equipment like the Nanovna. Although there were no mysteries, it all comes together to make magic. If you know stuff, you can do stuff! Thanks again de KN4ZXG, Ted.

While he has some great plans for modifications and improvements, at this point I think Ted should follow Farhan's advice and spend some time just listening to the receiver that he has built. Direct conversion receivers sound especially good. It is as if they are closer to the ether.

Here are some clips of Ted's receiver in action:

 

Congratulations Ted.  Welcome to the Hall of Fame.  

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:

https://www.youtube.com/@soldersmoke

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: 

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:

https://www.youtube.com/@soldersmoke

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:

https://www.youtube.com/@soldersmoke

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  

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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:

https://www.youtube.com/@soldersmoke

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!  

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Thanks to Andreas DL1AJG.  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:

https://www.youtube.com/@soldersmoke