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
It is great to see the enthusiasm that John KC9OJV shows for his newly finished DC receiver.
John writes:
I've finished the DCR- Soldersmoke style- what a great project. Everything went well- I added some caps to the amplifier power rail to tamp down the oscillation beast. It's on a compromise antenna here so can't wait to take it outdoor and put it on a full-sized antenna. I'm a manhattan style convert- what fun to build this way.
Congratulations John!
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This is obviously not the style of construction that we would recommend for new builders. Thus the "Honorable Mention" category. But Bruce is not a new builder -- in fact he has been a friend of the SolderSmoke podcast for many years: https://soldersmoke.blogspot.com/search?q=KC1FSZ When Bruce sent us the above video and a report on his build of the SolderSmoke Direct Conversion Receiver, we thought it was so cool that we wanted to share it with the community. Be sure to go to Bruce's GitHub page for more details: https://github.com/brucemack/kc1fsz-tjdcr
Bruce writes: My unauthorized modification is in the construction realm. I've built Bill/Dean's original circuit in a compact form on a commercial PCB. This was a good chance to practice with KiCad, Chinese PCB fabs, and SMD soldering. Huge thanks to Scott KQ4AOP for making me the PTO form! The rig works great. Thanks to Bill/Dean for leading such a successful/educational build project.
Hi Bill:
I had refrained from any postings of my work because the "purity" of my build may be called into question and I didn't want to create further distractions from your efforts. HIHI. If you scroll down this page you'll get an idea of what I've been up to: https://github.com/brucemack/kc1fsz-tjdcr.
I also see that you've switched away from the Schottky diodes which I have not done, so I'll make that change to see how it impacts performance.
Moving fully into the realm of unauthorized deviations, I've been experimenting with the simple "frequency offset" feature shown in SSDRA on page 218. Hanging that simple circuit from the high side of C2 seems to provide the hook needed for a simple companion CW transmitter module. Joking aside, I'd never built an analog VFO before the TJDRC project, nor did I ever learn CW, so it's been quite interesting to try to create a sister board that stays true to the TJDCR ethos but can still make legit contacts.
Thanks for all the work you guys are doing to educate the rest of us,
Bruce KC1FSZ
Dean and Bill:
What you guys have done with this project is truly amazing. I didn't build the rig in the "original wave," but I recently made one just for fun. I finally got around to looking at your Discord this weekend and was completely amazed... And Dean's tutorial videos are surely headed for YouTube platinum status!
Congrats and 73s,
Bruce MacKinnon KC1FSZ, Wellesley, MA
Bruce: There are several builders on Discord who would be very interested in your CW transmitter module.
That receiver is a thing of beauty. Steve AA7U is 78 years old and retired from the electronics industry. Now he does this just for fun.
Look closely at Steve's board. No pads! That, my friends, is the dead-bug technique. It is closely related to Manhattan style, but many builders prefer it. You see it in a lot of builds by Wes Hayward W7ZOI. I have some stuff built by Farhan using this technique.
You will also notice the absence of the PTO screw/coil. Steve made his receiver fixed frequency. But a member of the group has sent him one, so Steve may soon be tuining around the 40 meter band. FB.
But all four stages are there. And Steve did for us a lot of useful analysis:
Steve writes:
Hi Bill,
Attached is a picture of my DCR build. I used a fixed VFO since I don't have a 3D printer (but just learned two folks are offering the printed coil and have just ordered one). Mine is set for about 7130 kHz. I'm using the cheap eBay Chinese audio transformer 1300 ohms. I've done bench sig gen checks for weakest CW signal I can hear with headphones, swapping out different DBM diodes. 1N5819 -130 dBm; MCL ADE-1 mixer -129 dBm; 1N5711 HCD diodes -127 dBm; 1N4148 -130 dBm. My LO output was about +6 dBm. Note the proper way to check LO output is to disconnect from the DBM and terminate the LO with 51 ohms and measure the RF AC voltage across the proper nominal 50 ohm load, then convert to Vrms and use an online volts to dBm converter to get the LO power. Looking at the LO voltage connected to the DBM does not give a correct LO power reading (SSD and EMRFD also mention this). I see Dean's latest BPF comments (where I learned of the audio amp R14 100 ohms vs. 10 ohms typo) mentions the bypass cap on the LO jfet to increase LO output. I tried that yesterday and my LO output across 51 ohm load is now about +10.5 dBm (from the original approx +6 dBm) . The actual 8.2V zener diode voltage directly affects LO output too, I tested 10 diodes, the lowest was 8.05V, highest was 8.35V--higher voltage of course gives higher LO output.
(I'm 78 and retired from electronics, now do it for fun and hobby; I have a modest bench of test gear--various Siglent stuff including spectrum analyzer, etc. I've been homebrewing stuff for many years.)
Karl K5KHK wanted to build the receiver from junk box parts. But he did not have the needed AF transformer in his junkbox. So he designed an AF amp that would not need a transformer. That's great, but the circuit was a lot more complex than the one we designed for use by beginners. And we advised others to search for the needed transformer and to use the circuit we had prescribed. Thus the original "Honorable Mention" category. But this is no big deal. Karl has made great contribuitions to the radio art, and his circuit will, I think, be of use to those who want to build a different AF amp AFTER they complete the basic receiver.
NOTE FROM 28 March 2024: Karl found the right kind of AF transformer! He went the extra mile and re-built the audio amplifier using the transformer. FB Karl. You Honorary Mention status has been removed! Welcome to the full Hall of Fame!
Here it is with the simple AF amp that we are using:
Karl writes:
First Light! I know, I am a rebel and cannot follow instructions, but I wanted to do this from my stash (OK, mixing worlds here, that's what fiber artists call their junkbox of fiber, but I did join my wife this morning at a fiber fest). I do not have an output tranformer (I do have a few 600:600Ohm transformers). So here are my three answers:
1. Biggest challenge was to find a way to replace the output transformer. I did have a few baggies of BD139/140, so I researched small amplifiers wiith a complimentary output configuration and found one in John Lenk's "Handbook of Simpified Solid State Circuit Design", which apparently goes back to a Motorola application note (based on ancient transistors). After some noodling and heavy LTSpice'ing, I had something that looked like it would work, and it did, even though without anything connected, it blasted me with the local AM talk radio station (and some RF oscillation). A few strategically placed 0.01uF capacitors tamed the beast. What also helped with the design is that I found a schematic online without much comment (besides one who said "this will not work") that was based on the same design with more modern transistors.
2. I learned a lot about how to keep strong RF from messing with my AF amplifier, and that without having to put it into a shielded box.
3. I've started on two modules for Pete's PSSST transceiver when he first published it, but stuff got in the way, and I am motivated to pick it up again.
So again, the complete receiver was build with parts from my junkbox. This means that I had to make substitutions. I have for example a 5.1V Zener diode for the oscillator. It does produce enough power to drive the mixer, even with that lower voltage. I had smaller toroids on hand (-37 vs. the -50), so I had to do some math for the BPF to figure out how to wind them. I had no silver micas, and also no NPOs of the correct values, so a couple other values added up to almost exactly what I needed.
We are really pleased to have Tasmania in the group. As I typed Tasmanian D.... I almost typed Tasmanian Devil! But no, Ian's receiver is really nice.
The only reason I put it in the "Honorable Mention" category is the use of the large pre-made board. There is nothing wrong with using one of those, but in this project we called for the use of four separate boards and the Manhattan technique. And,earlier, when others started using something like this, we urged them to "go Manhattan" and they did. I hope Ian will understand.
The receiver sounds great Ian. Congratulations. 73 Bill Hi7/N2CQR
Early on, Andy sent in a report on a Direct Conversion receiver that he had built. It looked kind of like ours, but it was clearly NOT ours. It even had a 20 db RF amplifier ahead of the mixer. We politely (I hope) pointed out the differences. Andy quickly came back with the receiver picutred above. Yes, that is ours! Thanks Andy!
Andy writes:
I'm calling it done (for now)! 1) Biggest challenge for me was "coloring inside the lines". In other words, building the actual DCR challenge to the schematic vs. getting too creative with other circuits in my head. 2)My biggest breakthrough was developing a much better understanding of the diode ring mixer. And how brass displacing air in the PTO works. 3) What's next? I want to try some transformer-less audio amps to see if I can find a design for the folks that are having trouble finding a cheap source for the 1000/8 transformer. A super big thanks to both Bill @N2CQR and Dean @Soldersmoke for all the hard work bringing the DCR challenge and the Discord community to life. Bravo! And I would also like to thank Pete (N6QW) our guiding light and spiritual leader too. If it wasn't for the SolderSmoke Podcast and the Blog, I would still be living life as an appliance operator. 73 KB7ZUT ..
Andy posted these to the Discord server:
For more information on how you too can build the receiver:
Bill AB5XQ told me that his was an "Ugly Duckling" receiver. I would disagree with him. Any device -- like Bill's -- capable of pulling conversations out of the ether is, in my book, beautiful. Condgratulations Bill.
Bill wrote:
Well that was the first time I ever tried to record my work, so I know it is poor quality. My antenna is an attic dipole which is not optimum either. Yes I have tweeted the bandpass filter, but I am guilty of trying to touch it up by ear and I know I have gotten it off, so I will give that a go also. I am very happy with the receiver, I know it is an ugly duckling as compared to some of the others, but I learned a lot and know that I still have some learning to do. Thanks again to you and Dean for challenging us to get busy in homebrew.
73, Bill, AB5XQ
Thanks Bill!
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First, very cool sticker Roy. Thanks for designing this. We look forward to defacing cities, bars, and coffee shops across the globe with these stickers.
At the very end Roy ran into an unusual problem: His receiver did a good job with CW, but not so good with SSB. Hmmm. I remembered that we had a similar problem with Chris G7LQX. That problem turned out to be in the diplexer. With Roy's I took a close look at a picture he sent. He had C-16 as an electrolytic. Uh oh. What value did he have there? Roy told me that he had overlooked the decimal point and had put a 47 uF cap there instead of a .47 cap. Snip snip, a few minutes later all was well with Roy's receiver.
Great job Roy. Don't worry about the cap, that is exactly the kind of mistake that all homebrewers make.
Roy wrote:
It's finally done! Many thanks to Dean and especially Bill for all the help getting my receiver completed. I had a lot of challenges so it was hard to pinpoint anything in particular. Overall it was a tremendous learning experience in basic radio electronics and in the uses and limitations of my test gear.
Next up I need to finish the Norcal 40A I got about halfway done with before putting aside a year ago when I moved house. I also need to complete my PSSST-20 (Pete's Simple Seven SSB Transceiver) which I had barely started - I feel much better equipped to get that done now.
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Thanks Bill! And @Soldersmoke and lots of others on the Discord here as well. I did tune some SSB, need to add a larger plastic knob/cover to the tuning screw to make it a bit more easily tweakable. Learning process to hit it right on the double-sideband but when you get it dialed it sounds pretty good. Will try this evening and other times of day as well...
Congratulations Adam!
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This one is kind of "out there," on the fringes of radio respectability. But on the other hand Nate KA1MUQ has just took to a new limit the old ham radio tradition of raiding the kitchen for items that will serve the bases of support for new rigs. Usually, these items are wooden breadboards (hence the term). Nate has taken this quite a bit further, appropriating an entire frying pan because of its copper bottom. Nate reports that there is good news and bad news: The good news is that the receiver is working. The bad news is that his wife has banned him from the kitchen. It takes a brave and dedicated homebrewer to do something like this. Kudos Nate. But you probably should stay out of the kitchen.
Nate's receiver sounds great, and had provoked some much-needed humor on Discord: There were comments about too much bacon frying noise. And about the frequency readout being eggzactly right. Dead pan humor, and the possibility of a pan-adapter. FB!
Thanks a lot Nate and congratulations.
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For more information on how you too can build the receiver:
Nice job Piotr! Congratulations! In his comments he captures well the excitement that comes from listening to receiver as it first comes to life:
Piotr writes:
It's alive! Thank you Solder Smoke team. My winding on PTO bit loose, I think I'll just hot glue gun it. Tuning is delicate, but front panel added some friction. Need to swap audio pot (used linear I had handy), and speaker is 12R (from junk box). Audio stage has a lot of gain - that stage alone did pick up loud AM station with my finger as antenna :). Thanks again de Piotr KD9NHZ
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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Pete Juliano N6QW
Master Homebrewer
Dean Souleles KK4DAS
With beret and with a Michigan Mighty Mite in hand
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