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.
So cool that Alan did this. Here we see a rigrourous measurement of the MDS of our receiver, with a correction for the bandwidth. Very nice.
It can discern signals down to -125 dbm. I think that is pretty good for simple receiver like this.
Alan agrees that another way to do the sensitivity test is to just listen for the band noise when you connect and disconnect the antenna. Especially on the low HF bands, if you can hear it, you have sort of maxed out on receiver sensitivity.
My comment: Good post with good points about the under-appreciated differences between true homebrew and kit building. I have a lot of Heathkits around me, but I never considered them to be homebrew. There is a big difference. We have been promoting and supporting the HOMEBREW construction of 40 meter direct-conversion receivers. No one would confuse these receivers with commercial, or even kit-built gear. But they work very well, and the builder earns the satisfaction that comes with building something from scratch. There are no factory made PC boards to “populate.” All four of our boards are made using Manhattan construction techniques (super glue, isolation pads, copper-clad substrate). Almost 90 receivers have been completed, in more than 15 countries. Check out the receivers. Build one if you dare:
Hall of Fame member Steve WD4CFN in Tennessee fired up his 40 meter Mchigan Mighty Mite (above) and made contact with ND4K in Georgia. FB Steve. Congratulations OM!
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.
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.
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!
We were very pleased that Phil W1PJE was able to visit yesterday. Phil is the Director of MIT’s Haystack Observatory. He is very knowledgeable on topics related to space and space technology. He is also a member of the SolderSmoke Direct Conversion Receiver Hall of Fame. We talked about the history of the Haystack Observatory, famous antennas (dishes), and about the SolderSmoke Direct Conversion receiver project. It was a lot of fun talking to Phil. We managed to shoot this video with him. Thanks Phil and thanks Dean.
We were already very proud to put Alan Wolke W2AEW in our Hall of Fame. But Alan put icing on the cake this morning by making his own video about his build, along with some pre-CME video of the machine inhaling CW and SSB (see above). The SSB is DX, from France. FB Alan, thanks.
My only comment to Alan was on the frequency readout. I noted that many builders had resorted to San Jian PLJ frequency counters. A few others had done what he did and used the frequency readout feature of their Tiny Spectrum Analyzers. I told him that at first I had gone very low tech. It was in fact, quite barbaric. Check it out:
I think it is kind of low-tech cool. I am a bit disappointed that none of the builders have done anything similar. Mark KI5SRY came the closest, but his solution was relatively spophisticated. Look, it is not to late. Get out those index cards and calibrate those screws! Send in pictures or videos.
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,
This goes to prove what we have been saying all along: this receiver is not a toy! It is capable of operating as part of a real 2-way ham radio station. Hall of Fame member Scott K1OA has paired his receiver up with a Merry Christmas transmitter designed by Walter KA4KXX and has been making CW contacts with it (see above). Walter supplied the crystal and many of the needed parts. Scott has already workedWA9RNE, N4HAY and W3RJ, and has tried making contact with Walter but no luck yet. He has gotten RBN reports from Germany and New Zealand. All that with just 3 watts.
This is not the first time this receiver has been out to use. I made one contact with it using a “Ten Minute” QRPp transmitter that I had intended only to use for test purposes:
And who can forget HoF member Nate KA1MUQ who turned his “frying pan” direct conversion receiver into a double sideband transceiver and used it to make phone contact with Idaho from California:
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
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!
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!
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.
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.
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:
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!
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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.
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.
