Jay KI5VIR is a new ham, but you would never know this by looking at his build of the direct conversion receiver: It looks like something built by someone with a lot more time the amateur ranks. (See above.)
Jay writes:
I have completed the direct conversion reciever and I can't thank Bill, Dean and those that commented and asked questions on discord enough. This was my first build and I can't believe how much I learned. I have a long ways to go, but this was just what I needed to get started in homebrewing. 1- (BIGGEST CHALLENGE) was probably the diode ring mixer and learning to use my scope and setting it up to test the circuit. (this was also the most rewarding stage) 2-(WHAT DID YOU LEARN AND WHAT WAS YOUR BIGGEST CHALLENGE?) I got a basic understanding of how to read a circuit and what different components do in the circuit.(I still want to revisit each stage and make sure I get a little more) 3-(WHAT WOULD YOU LIKE TO HOMEBREW NEXT?) I want to first dissasemble each board and rebuild while it is fresh in my mind and make sure I get a little better understanding. After that, I want to either build a transmitter to go with this reciever, or build a complete transciever. Not sure whether to build ssb or cw, but I definately want to build something I can make at least a few contacts with.
Congratulations Jay, and welcome to the Hall of Fame!
Dave Richards AA7EE is justifiably famous in homebrew circles for the beautiful photographs of his rigs, and for the superb documentation of his builds. You will see what I mean when you visit his blog:
We were very pleased when Dave told us he would build the direct conversion receiver that we have been discussing on Discord.
Dave writes:
Phew! Well this was a bit of a journey, and a slightly humbling experience. I looked at the schematic and thought, "Hey, I can build this. Shouldn't be too hard!" But the homebrew Gods judged that it was time to remind me of my place in the big scheme of things, by imbuing my receiver with in-band breakthrough from SSB, CW, and digi stations. Strong in-band stations within about 50KHz were breaking through and being heard in the same way that you'd hear SSB, CW, and digi signals on an AM receiver without a BFO. Their pitch wasn't changing as I tuned, because they had no pitch. Bill suggested that RF was getting into places it wasn't supposed to be, and being envelope detected by the AF amp. As it turned out, he was right. If anyone's interested, I can post a video of the issue I was experiencing. In the meantime though, I'll keep this post brief. I have quite a lot of pictures from various stages of the build, but posting them all here might be a bit TMI.
I wanted to make this receiver reasonably compact and build all the stages on one board. My near-pathological tendency to try and build things fairly small could have contributed to the breakthrough problem that I experienced. I won't go into all the details of the troubleshooting process here, unless people are really interested, though I'll detail them in a post on my blog, as I think that sharing this stuff can be helpful to other builders - just as I have benefited greatly from others sharing with me.
I made a few small changes from the original schematic, to cure the issues I was experiencing. Will detail them in another comment underneath, as the free version of Discord puts a character limit on posts.
I made the following small changes, to cure a couple of issues this little receiver was experiencing -
1) The AF amp was motorboating at anything above about medium volume, so I swapped out the 47µF capacitor in the +ve supply line to the AF amp (C10) for a 470µF part. This killed the motorboating dead in it's tracks.
2) To solve the in-band breakthrough issue, I did two things -
a) At the suggestion of Peter VK3TPM, I placed a 1K resistor in the +ve supply line to the first AF amp stage, Q5, between C15 and R8. In conjunction with C15, this forms a lowpass filter with a 3dB cutoff point at about 3Hz. With a 12V supply, ~3.5V is dropped across this resistor and at 9V, the voltage drop is ~2.3V. If this voltage drop is too much for you, you can try a lower value of resistor and perhaps increasing the value of C15. This voltage drop does decrease the gain of the stage a little. In my case, it was welcome, as the amp was tipping over into feedback at full volume. Adding the resistor eliminated this, so I can now run the AF gain pot at full tilt.
b) I added a 0.22µF capacitor from the wiper of the AF gain pot to ground, as an RF bypass. Physical placement of this cap was close to Q5. It also shapes the audio a little, cutting out some of the high-frequency hiss. You can experiment with different values here. I was initially going to use a 0.1µF part, but 0.22µF provided better protection. Greater values cut out too many of the higher frequencies for my liking. For a relatively simple receiver like this, I like the wide open sound.
I removed the spring from the tuning shaft. Tuning is smoother now, and free from backlash.
Dave
AA7EE
Here is a video of Dave's receiver inhaling CW during the CW Sweepstakes contest:
Here is one of Dave's iconic photos of the receiver:
Thanks Dave! Congratulations and welcome to the Hall of Fame!
-- We are over 100 on the Direct Conversion Receiver Builds. We talked about the receiver project at the GQRP convention. Video on the blog.
-- G4 Geomagnetic storm November 11-12. Messed up my computer. Blackout in the DR?
Pete:
-- USMC Birthday. Having served alongside them they have my deepest respect. Veterans Day.
-- Think about supporting those without a job this Thanksgiving. Cash to various organizations is best.
-- 50 Hz off frequency -- What does that mean if you tune by ear and not by mouse/waterfall?
-- The Hybrid Wireless is on the air. A unique build and not often seen.
Dean:
-- Progress on the HOMEBREW MOSFET amplifier. Claude helped.
Dean's 100 watt amplifier
SHAMELESS COMMERCE DIVISION: Mostly DIY RF. Become a SolderSmoke Patron. Buy stuff from Amazon through the link on this blog (in the right side column).
Bill:
Bill's antipode from Virginia
-- VK early in the morning. Also E51MWA and FW5K. All homebrew SSB. My antipodes. VK6ACF Charley 11,629 miles. Might be my most distant station worked.
-- Camden is a 23 year-old blind ham who is looking for some homebrew help. He lives in Pleasant City, Ohio, about an hour east of Columbus. Can you help him? camden@bopp.net
-- Dave AA7EE A completely AI SolderSmoke? "Open the pod bay doors Hal."
-- Pat W3RGA heard my 1 watt HI7 beacon. Thanks Pat.
-- Patrick Voets -- A Belgian living in the Netherlands -- supports our defiant NIMCEL position!
-- Brian "Moses" Hall K8TIY, Father of Robert of "Crank it in Robert" fame. Check out the video. Young Robert appears around the 45 minute point: https://youtu.be/Xqs2Ihucr6I?t=2730
-- Will Harris KI4POV -- an esteemed homebrewer -- asks about using 75 ohm coax. I say yes, Pete tells him how to do it right.
It was really good to see Puneit Singh finish this receiver project. He overcame many difficulties, including a lot of travel and an acute shortage of time, but he got it done. Congratulations Puneit Singh and welcome to the Hall of Fame.
Puneit is also a CW man -- we hope he pairs this receiver up with a simple CW transmitter and makes some "fully homebrew" contacts.
Thanks to the ARRL for the award. It is much appreciated. Thanks too to all the people who built this receiver. There are more than 100 of them and they come from all around the world. We hope that they will go on to become homebrew Elmers, and help others to discover "the magic that emerges in a room full of solder smoke, and that only comes from a receiver that you have built yourself."
And special thanks to Bruce KC1FSZ for nominating us for this award.
Congratulations to Karl EI9ITB for the successful completion of his SolderSmoke direct conversion receiver. Above you can see Karl's receiver inhaling SSB on 40 meters. We also got a nice CW video.
Karl worked hard on this, taking seriously our admonition that builders should try to understand each of the four stages. Karl went the extra mile with the audio amplifier, building a virtual copy in a simulator. Karl is following the long Irish tradition of being "radio experimenters." FB Karl.
Karl is our first ever builder in Ireland. This receiver was built in Ireland. Karl is American by birth with the call sign of KB8SWH.
We were really pleased to have been invited to speak to the GQRP club's 2025 convention. We talked about the SolderSmoke Direct Conversion Receiver project. There were some recording glitches, but we managed to re-create the presentation. Video appears above. Thanks again to GQRP!
Admirably, Todd W2TEF proved that you can build this receiver even if you don't have an oscilloscope. He used a lot of simple tests, including listening for the band noise when he had all four boards finished. He got the kind of help from friends that all of us use while homebrewing. And he tuned in SSB signals for the first time. FB. SSB in the video above, CW below.
Todd writes:
... thanks to Dean and Bill for putting this together and guiding me into a great beginning project. And to Chris and others offering guidance here in Discord. I love seeing a project through to completion, and am still amazed that twisted up coils of wire can grab intelligence out of the air!
Wow, congratulations to Philippe F1GMA for his wonderful build of the SolderSmoke Direct Conversion Receiver. Phillipe deserves extra credit for achieving this goal while working in a foreign language, and with parts acquisition even more of a challenge for him. That AF transformer was hard to get in France. And I see that a companion CW transmitter may be in the works. FB.
The SSB signal that Philippe provides includes a clip from special event station TM120ESP. That station commemorates the 120th anniversary of the first Esperanto congress. FB. TRGHS!
Congratulations Philippe and welcome to the Hall of Fame. I think you are our very first French builder.
This was the 100th SolderSmoke receiver! It was really cool to see Chris KN4GAH's receiver inhaling CW (sbove) and SSB (below). I especially like the ink pen markings on the pine board. FB. Maybe make note of memorable QSOs heard, or -- later -- contacts made with this receiver.
Chris is an electrical engineer, so it was particularly useful for us to get his perspective on this project. We started this at the High School knowing full well that most of the students would spend their careers in the high tech, digital world, and might never again touch a soldering iron. But we thought it would be good for them to build something like this at least once. Chris comments on this idea below.
Chris writes:
Thank you for putting this all together for all of us and creating such a great community full of knowledgeable and helpful people.
I work as an RF engineer and mentor a few junior RF engineers and will be proposing this challenge to them as a learning opportunity. As this challenge provides a lot of insight into how common blocks used in RF designs operate. It is just too easy to go on mini-circuits and find a filter, amp or mixer that meets ones needs. Actually building these components provides valuable knowledge that all us RF engineers should have.
Thanks Chris, Congratulations and welcome to the Hall of Fame!
Chris KD4PBJ is one of SolderSmoke's most loyal fans. Over the years Chris has supplied many of the parts and ideas used in SolderSmoke projects. We were really delighted when Chris took on the Direct Conversion challenge. As you can see, his build was superb.
Chris had promissed to have the receiver completed by September 2, 2025. As it happens, that was the day of some very powerful solar activity and very poor band conditions. So the video above doesn't really do justice to Chris's receiver. We hope he will send us some more video, perhaps under better conditions, and perhaps with some more SSB.
As you can see from this message from Chris in mid-July, he is a busy guy. We were pleased that he found time to build this receiver. Chris wrote
Good Morning guys! I spent my July 4 weekend and 1200 round trip miles heading up to Richmond to pick up two 50 watt decommissioned airport non directional beacons that I hope to get working on either the 630m or 2200m bands. I'll most likely just use the amplifier, power supply and matching sections as they are modulated CW which isn't permitted. At least I have a nice high current power supply, outdoor enclosure and inner workings. I was told one worked and one doesn't. I got them off eBay and the seller is a television engineer in Richmond named Greg. He listens to Soldersmoke too and is a builder like I am. He said these are government surplus from a place called Camp Peary in VA.
The DC receiver is still coming along, I've just been overwhelmed with things on my to do list as well as a new job (learning lots about high power lasers) so I promise it will get done soon.
Chris
Here are a couple of pictures of Chris's receiver. Thanks Chris, and Welcome to the Hall of Fame.
The pine board is key. Frank Jones (W6AJF) would approve. FB Dave. CW video above and SSB below.
Dave writes:
Bill,
After many diversions from the work bench I finally got the Solder Smoke Challenge Receiver to operate. There were the usual problems with the audio amp but my main problem was a faulty trimmer in the BP filter.
I hope I’m in the first 100 to complete the project.
Hopefully the attached videos make it. One is a CW and the other is SSB.
It is amazing that Robert (who is not yet licensed) got this receiver to work. Check out his homebew coil form. Excellent work Robert. Congratulations and welcome to the Hall of Fame.
Here is a Dicord exchange with Robert. I think we see the true homebrew spirit here:
Bob K2BVR homebrewed a really nice SolderSmoke Direct Conversion receiver. On his "Proof of Life" video we hear some nice SSB signals, some great CW signals (including N7DZ/6 POTA) and even the well-known tones of FT8. FB Bob. Congratulations OM! Welcome to the Hall of Fame.
Bob writes:
Hi Bill,
I wanted to send you a quick note of thanks. I’m very grateful to the SolderSmoke Discord users for their help, and to you and KK4DAS for all of the work you’ve both done in developing this project and sharing it through your videos.
I’ve been making progress on my build and thought I’d share a little update. I ran into some challenges with the bandpass filter – it turns out that reducing the trifilar winds per inch helped improve the performance. I also fought with a shorted test fixture along the way, which made things more confusing than they should have been.
On the audio side, my first amplifier module is still giving me trouble. I hated not getting it fixed right away, but I’ll be coming back to it. I did have to add a 470uF cap to the power rail to control oscillation but I haven't added the 220 ohm resistor. I’m thinking about putting the different modules into their own boxes so that I can experiment with them more easily in the future.
Thanks again for all of the inspiration and guidance — I really appreciate it.
I was really pleased to see Shane G0JNR finish this receiver. He has been an active member of the SolderSmoke community for many years. For example, back in 2018 we see him commenting on KU4NO's FB rig:
Shane G0JNR here. I've just got my Soldersmoke DC rx up and running!
The thing that put me off earlier in the year was the 3d printed coil former.
But my son has now got one and printer and printed one for me - as an added bonus, it glows in the dark!
It didn't work straight away but perseverance has paid off. 73
Thanks Shane! Congratulations and Welcome to the Hall of Fame.
Although we had strongly suggested that builders FIRST build the receiver in accorandance with Dean KK4DAS's excellent videos, we also told builders that once they got those receivers working, there was, of course, no limit on the modifications and circuit changes they could make. We are very pleased that Brian KI7KLB has followed this advice.
Brian writes:
The KI7LKB DCR has been modified to include the KK4DAS 3rd stage of the audio amp, a QRP guys frequency counter, and an enclosure made from scrap aircraft aluminum and hardware. My favorite mod, however, is the WB6AMT (SK and former Elmer) voltage regulator circuit. It allows me to power the DCR from the shack 13.8 volt power supply while simultaneously providing 9.5 volts for the radio and 12 volts for the frequency counter. While I ordered components from Digi-Key, it was fun to include a coat hangar, spare aircraft hardware, scrap wood, and repurpose the frequency counter from another project.
Congratulations to Grant K0GDB on his FB SolderSmoke Direct Conversion receiver. Welcome to the Hall of Fame Grant! That PTO former is especially FB! Grant is a relatively new ham, making his smooth construction of this receiver even more admirable.
Grant writes:
Proof of life video! Many thanks for the helpful YouTube tutorials, everything went together pretty smoothly.
The windings are actually as close to the specification as I could get them on the nanoVNA. It's been a bit since I built that part, but if memory serves I had one fewer turn and had to do some bunching to get it to read correctly. The main difference in the PTO is that I made the former on a laser cutter from slices of quarter-inch plywood since I don't have a 3d printer. The center cyllinder is actually just rolled up paper.
Opening: Travel notes: Pete to Denver. Dean to Alaska. Bill in the Dominican Republic.
The future of the podcast. We will embrace our NIMCEL status and fight on in spite of the AI Apocalypse. Thanks to Peter VK3TPM, Hamilton KD0FNR, Sam AI7PR, Todd K7TFC and the WayBackMachine for providing backup and transfer options for the blog. Google could end Blogspot at any time.
Dean and Bill win the 2025 ARRL Technical Service Award. Thanks to Bruce KC1FSZ for the nomination. And thanks to Bill Morine N2COP for letting us know. 91 receivers completed so far!
SolderSmoke East was pleased to host Phil W1PJE, a distinguished MIT radio astronomer AND member of the SolderSmoke Direct Conversion Receiver Hall of Fame.
Dean: Amplifier design, woes, triumphs, tribal knowledge. And help from Claude.
-- Eleven contacts on 40 with the DC RX and a Tuna Tin 2. Mike Bryce WB8VGE came back to my CQ! First ever QSO with SolderSmoke DC receivers on both sides: K1OA-N2CQR.
-- Do real hams use ALC? Do we really NEED ALC?
Mailbag:
Who is the Project 326 Guy? A British engineer resident in China for last 20 years.
Steve EI5DD Ham Radio Ireland magazine. Hey -- Why no Irish DC RX builders?
Mike EIOCL -- Always great to talk on the air with an old friend.
Walter KA4KXX -- I checked into the Sunrise net! With my HW-101! Thanks Walter.
Farhan VU2ESE -- Watched our interview with Phil W1PJE
Phil W1PJE was an SWL with an old Halli receiver. VOA? Boo! But Radio Marti is BACK! Also, the hydrogen line from the cosmic dark ages has red shifted to... 7.1 MEGA hertz! So LISTEN UP!
Phil W1PJE with a Halli and the Haystack Observatory Dome
Bill WA5DSS built this beautiful receiver back in December 2024. Somehow I failed to include him in our Hall of Fame. Well, better late than never, right? Please let me know if we have missed anyone else.
I think it looks and sounds great, on both CW and SSB. Note the Costa Rica station in there in the SSB portion of the recording.
Back in December 2024, Bill wrote:
Bill, Dean, I forgot to send you a recording. This is what I recorded last night. I did not let it “warm up” so the stability is a little better after awhile. Also, I have a knob for tuning…just haven’t hacked off the head of the bolt yet.
I have put the receiver up for now. I am trying to get a Heathkit DX-60 on the air for New Years Eve Straight Key night. It’s the only time I attempt a straight key. Also I am amazed at how difficult it was to operate these old cw radios. No wonder I didn’t get many contacts back in the early sixties...
...This has been an interesting project for me. I have built many kits since becoming interested in electronics during the 1960s but this is the first time I have started with unetched boards. I think I prefer the “dead bug” style over Manhattan. I don’t have the patience to plan out where all those islands go!
