Just go to http://soldersmoke.com. On that archive page, just click on the blue hyperlinks and your audio player should play that episode.
http://soldersmoke.com
Mark KI5SRY came up with a very innovative solution for the tuning dial problem. See above. My solution was much less sophisticated: At the suggestion of VK3YE, I just put a calibrated card underneath the screw. By looking at the screw edge from above, I could get a rough estimate of where I was in the band:
Looking back on his successful build of the receiver, Mark wrote:
You made this pretty straightforward. My biggest challenge was trying to understand what was really happening in the circuit.
I learned how to use my oscilloscope, seeing the oscillator come to life was great.
I would like to build a transmitter or a complete transceiver.
Bill, thanks to all of the effort you and Dean are putting into this project. There was definitely a magical feeling dialing in and getting legible sound out something built on my bench.
Very cool Mark. Congratulations!
---------------------------------
For more information on how you too can build the receiver:
Wow, Jeff N0NQD built a beautiful receiver, and has been bitten bad by the homebrew bug. Jeff admitted that he recently went to a gala with his wife. He was preoccupied with the problems he was having with his DC receiver. Suddenly DURING THE GALA he remembered having mis-identified two capacitors in the mixer. So he and his wife HAD TO GO HOME FROM THE GALA so that he could fix the problem. And apparently he is still alive, and married! Amazing!
Jeff wrote:
I have been a ham for just about 40 year and typically build kits lots of them most recent the QMX. I found a new passion and seemingly addiction now because of this build. My next Home-brew project is probably going to be a transceiver or a complex receiver not sure what type just yet. It has been so much fun and highly distractive to be apart of this Soldersmoke DCR family. And hope this continues!! Thank you and 73 Jeff N0NQD
Jeff N0NQD's Bench
Thanks Jeff. Congratulations!
---------------------------------
For more information on how you too can build the receiver:
Erik built a really nice receiver. I was glad that he took to heart our advice on the need for a large, insulating tuning dial. He made one! As he made this entire receiver.
Eric wrote:
I would like to make a homebrew QSO! I am learning CW, mainly because I find it easy to use QRP/POTA. I have a Michigan Mighty Mite, but it has not reached farther than my backyard yet, so a CW transmitter in the single Watt range would be a great next project.
Congratulations Erik!
---------------------------------
For more information on how you too can build the receiver:
All the way through, Ryan displayed a desire to really understand each of the four circuits included in this receiver. He wanted, as Maxwell said, to know not only the "go of it" but "the particular go if it." FB!
Ryan wrote:
Here's a short video of my receiver in action. I'm very pleased to be receiving real radio! I'm too inexperienced, so don't really know if this is good or bad performance for this receiver. This is about as good as I've gotten so far. A few people I can understand well, but many are not really intelligible. Thanks to everyone, this is a fun project!
I think it sounds great. Tuning in an SSB station with a DC receiver is an aquired skill -- we all get better at it over time.
Congratulations on building a really nice receiver Ryan.
-----------------------------
For more information on how you too can build the receiver:
Above you can watch and listen to Wayde's receiver as he tunes across 40 meters. It sounds good, even though Wayde is thinking about some improvements.
It was highly appropriate that Wayde's first reception report should be of CHU Canada, the Canadian time signal on 7.850 MHz, a bit above the 40 meter band, but clearly in tuning range for an unmodified SolderSmoke direct conversion receiver. CHU is probably unique in the world in that it is transmitting the carrier and JUST ONE SIDEBAND. It transmits only the upper sideband. This makes it clearly detectable by our receiver. As Dean pointed out to Wayde, all he had to do was "zero beat" the carrier with the PTO signal (tune to the point where they are on the same frequency and the audio tone disappears). Because there is only one sideband, the direct conversion receiver can demodulate it very well. If there had been two sidebands, this would have been a standard AM signal, and our little receiver -- which does very well with SSB and CW -- would have been unable to demodulate the signal without distortion. (For an explanation of why this is, see: https://soldersmoke.blogspot.com/2022/12/but-why-why-cant-i-listen-to-dsb-or-am.html Warning -- this is kind of in the "advanced course" category.)
Here is an overhead shot of Wayde's receiver:
This is a really nice build. The use of what appears to be a kitchen cutting board harkens back to the early days of radio when young hams took the cutting boards from their mothers' kitchens and used them as bases for rigs. This is origin of the term "bread board." Frank Jones continued in this tradition by building most of his rigs on wooden boards. Wade's DC receiver continues in that tradition.
Wade was able to decode some FT8 picked up by this receiver and recorded on his phone:
Congratulations Wade!
----------------------------
For more information on how you too can build the receiver:
Ken W4KAC tells me that the tuning knob that he used to minimize hand-capacitance effects on his PTO started out as a gear in a leaf blower. I commented that the engineers who designed that gear surely never thought that it would someday be used in a homebrew direct conversion receiver.
Ken lamented the polemical nature of the SSB discussion captured in the above video, but the clip does give a good demo of the SSB capabilities of Ken's receiver. And the video gives some nice close-ups of the receiver itself.
Ken is a CW guy, and he has already homebrewed a QRP CW transmitter that he hope to pair-up with the receiver. Here it is:
Good morning. Just wanted to say, don't give up if your receiver is not quite right. Mine was working, I even posted a video here. When building the AF amp from the transformer end back, the Q4 stage was fine. I added Q3 and had a "motor-boating" oscillation when I applied a signal. I tore it all off the board and started over. I still had the problem, so being stubborn I continued on and kept adding more filter caps to quiet it down all I could. The receiver worked and sounded pretty good during the day when I copied WA4FAT and others. That evening was a different story when the band was working well and very full of signals. Very strong stations were ok, but I was getting lots of "hash" and noise other than normal band noise. FT8 was breaking through weakly all over the band along with other unidentified stuff. Yesterday morning I grabbed a new piece of copper clad and built and entirely new AF amp. It tested properly all through the build. Instead of installing that board I decided to find the problem with the original. I "thought" I had used new transistors when I rebuilt it the first time. Turns out I had probably put the original Q3 back, because replacing it cured the problem. I had an entirely different receiver last night. A pleasure to listen to. Don't give up like I did at first!!
Ken went the extra mile by building a SECOND Direct Conversion receiver. So he may soon get TWO Hall of Fame credits. Here is the second one that Ken built:
Jason did a great job on this receiver, hanging in there as he worked to overcome techincal difficulties, some of which were related to test gear. That is a big part of the homebrew process. The receiver looks and sounds great Jason. Congratulations.
Jason wrote:
I really like the camaraderie and elmering during the process. Not to mention seeing the different builds and how people approached the design. That helped me, as I’m a visual learner. I’ve been a ham for almost 40 years and I love building rigs. This was a blast.Thanks again, Jason WV3V
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For more information on how you too can build the receiver:
Herodotus once said that "learning is not child's play -- we cannot learn without pain." I think Jim KF8BOG proved that in this build. I'm sure he burned his fingers at least a few times. I remember fondly almost seeing the light buld turn on when Jim came to understand how the diode ring mixer really works. He struggled to tame a rebellious AF amplifier (we've all been there). Throughout Jim demonstrated the persistance and determination that are needed to turn a bunch of parts into a well-functioning receiver. He did it. He built it. Congratulations OM!
Jim wrote:
I am not just an appliance operator now but only half way through. Time to make a transmitter!
A little about me I became interested in Ham radio about 45 years ago in Boy Scouts I tried really hard with my Radio shack straight key and morse code chart to learn code by myself and just could never get it. Fast forward to last year and I had a friend who did CERT and he told be about it and said he used 2 meter for communications I was impressed and said “how did you learn morse code?” he replied “ I didn’t you don’t need it anymore” I promptly signed up for Ham in a day in June and got my technician license and my then my general in August. I have been studying radio ever since. This project was perfect for me. I like to make things I have been a mechanic for 40 years plus ASE master. Fixed all sorts of crazy electrical issues but DC and RF are way different lol.
Again Thanks Bill and Dean you don’t know what you have started. 73s KF8BOG
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For more information on how you too can build the receiver:
In many ways it was for guys like John W8UC that we launched this project. These are guys who have been hams for a long time, but -- like most hams -- never built anything. Most guys don't see this as a problem. But some guys just don't like to think of themselves as "appliance operators." For years the ARRL and others told hams that receivers were just too difficult for them to build. We found this not to be true. So we launched this project, first at a local high school, then to a larger group.
In his comments John says he has been an appliance operator for 48 years. Well, you are an appliance operator no more John -- you have built a receiver.
John wrote:
I can hear the signals on a receiver I built so I am super happy about that... I have learned more in the last month about how a receiver works than I have in the last 48 years of being an appliance operator. Thank you Dean and Bill. 3. Would like to build a transmitter next. Also a receiver for another band.
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For more information on how you too can build the receiver:
Dean and I often say that we too have learned a lot from this project, and that the receiver has gotten better as a result of all these builds. But in KE2AMP's case we really see an innovation that nobody has used before. But it is a great idea and it solves the "loose screw" problem of the PTO. Check out the spring on John's PTO. That is really smart. Thanks John.
John also sent me a crystal wrapper that will long be cherished by the CBLA (Color Burst Liberation Army):
John wrote:
Well I completed my DCR, and am receiving signals on 40 meter at 1900UTC. My audio amp will oscillate if I turn up over half way and my pto is little loose and makes it bit hard to tune. I put a light spring behind the pto bolt to give it some friction and tighten up. I’m thrilled that I’m receiving signals. I still want to add a front panel to mount the volume pot, the on/off switch and speaker if I have the room.
I am so Thankful to Bill, Dean and everyone on the discord for this project I learned so much more being able to ask questions and follow along with other builders as we worked through each stage of the build. I definitely learned some things about oscilliscopes. And testing each of the stages as we went along.
I would like to try my hand at a SSB transmitter to go along with this receiver. I have built a working MMM but was just to see if I could. I don’t know CW
Oh and I included pic’s of something Bill will like.
Pick it up at a ham fest last summer.
Will that get me into the color burst liberation army?
Thanks Again, 73
de John KE2AMP
Consider yourself inducted John. The CBLA needs innovative people like you!
-------------------------
For more information on how you too can build the receiver:
It was really great to hear those Australian voices coming from Phil's receiver. Check out the video above.
Phil writes:
Completion! So pleased, it works really well. And there were lots of lessons for me along the the way. Thank you Dean, Bill and Pete, it's been a great way to get me into homebrewing. 73s from sunny Queensland. Phil VK4PG
I also like Phil's front panel. Note how he put to use the circular piece that remained after cutting the speaker hole; that became the tuning knob. FB Phil. Thanks.
For more information on how you too can build the receiver:
Derek N9TD was another of the early builders of the Direct Conversion receiver; he has done really magnificent work. He is an Electrical Engineer, and you can see in his work (and in the email below) the tension that exists between the desire for simplicity and the urge to improve. In the above photo, for example, we see that Derek had already gone ahead with the installation of an RF gain control. We also see his use of a steel screw and an outboard coil in series with the PTO coil. All of these mods are fine -- I have used all of them. We just advise newcomers to build the basic receiver first, then put in mods from there.
Derek has gone the extra mile (many miles in fact) by building a Double Sideband transmitter to go along with his receiver. We know many will want to do this. Our advise remains: Build the basic receiver first, get it working, then do the mods, perhaps culminating in the build (as Derek did) of a Double Sideband transmitter and the creation of a DC-DSB transceiver.
Here is a video of just the receiver in action.
Note that the DSB transmitter circuitry is on the board:
And here is Derek demonstrating a phone contact with the resulting DC-DSB transceiver:
Derek wrote:
Bill,
Let me introduce myself, I am a recent electrical engineering graduate from Purdue and a long-time listener of the podcast. I want to thank you and Pete for being one of the reasons I chose to pursue my degree in the first place. I'll admit that in the more difficult stretches of getting my degree, I often pulled out the podcast to be reminded of the fun that can be had with radio and electronics.
Until recently I had to hang my head low along with the majority of the other 'appliance operators' out there having never built anything with my two hands that can be used to pull signals out of the ether.
I am no stranger to building projects, PCBs, and melting solder but I usually chose to either stick to the dreaded digital domain or focus on antennas, filters, and other ancillary equipment. The logic being that I like to have a "known good" radio for the shack and that I would focus on other equipment to supplement the radio. I still follow this logic when I want to contest and we all know that antennas are well worth the effort, I've just finally had enough of being an appliance operator and have your podcast to thank for the extra push.
I had been following the original effort of the TJ DCRX with interest from the start and earmarked this project as one I would like to build based on its inherent simplicity and good performance. However, the demands of school and a recent (at the time) abortive attempt to build an AM superhet with an SA602 the year prior made me (I got as far as feeling the joy of oscillation but regretfully petered out after that) put this one the backburner for about two years until December 2024.
By coincidence, I independently decided to start this project just before your show with the HRWB folks and the gauntlet being thrown down, which has spurred many to build this receiver. It has been great to see the extra coverage on the receiver, and the commentary has been very insightful for someone trying to build this for the first time and with as many of the "improvements" as possible.
For better or for worse, I'm the type of guy who wants to understand the "why" behind all the design choices and, from there, try to incorporate as many lessons and improvements as possible to make the "best" version possible. I'm not saying I make the best version of anything, but it's just a quirk of the way I think and justify doing a project. It always has to be "this and some additional improvement;" otherwise, I would decide against doing it.
Rambling aside, I ended up building the DCRX, adding the RF attenuator from N3FJZ's website, and incorporating the lessons you learned after experimenting with improving the tuning on the PTO. I added an external series inductor wound on a dowel rod and used a zinc-coated steel screw as opposed to brass. I found that this gave solid tuning performance across 40m and was easy enough to tune in CW or SSB signals (after 3D printing a large knob for the PTO bolt). Alan W2AEW's video on mixers was a great tutorial to use to verify that my mixer was mixing. With the radio assembled I was treated to the joy of hearing my receiver breathe in the sounds of 40m for the first time last weekend and even managed to copy some Croatian DX during last week's contest. As Farhan said to do, I have spent the last few days enjoying the receiver and figuring out its quirks before moving on to the next step.
The only "issue" I have noticed is that I still get some AM breakthrough despite tuning in the bandpass filter. The problem is very noticeable if I accidentally put my finger on the wires going to the AF gain pot. If I do that the AM station is the only thing I can hear. This makes me think the problem is after the bandpass filter and more investigation is needed. Maybe using coax on the control lines to shield it will help? Regardless I am impressed with how well the receiver sounds, the stability of the oscillator, and the effectiveness of the simple audio amp....
Again thank you and Pete for your work on the podcast and for helping inspire countless homebrew radio operators!
73s,
Derek N9TD
--------------------
Thanks Derek. And thanks for helping other hams get the 3D printed PTO coil forms that they needed.
For more information on how you too can build the receiver:
"SolderSmoke -- Global Adventures in Wireless Electronics" is now available as an e-book for Amazon's Kindle.
Here's the site:
http://www.amazon.com/dp/B004V9FIVW
Bill's OTHER Book (Warning: Not About Radio)
Click on the image to learn more
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Master Homebrewer
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