Category: TJ DC RX

David AI6WR’s Beautiful SolderSmoke Direct Conversion Receiver

David AI6WR was a patient craftsman during the build of his receiver. He diagnosed and fixed defects in the AF gain controls that he was trying to use. He hung in there, found the problem, and fixed it. Even with a challenging antenna situation his receiver is pulling in SSB signals on 40 meters.

David writes:

Thank you everyone for the suggestions! I have tried a bunch of them out, those that I could try without making a ton of changes. I have made a couple of changes and it’s working much better now. It turned out that one of the major contributors to the unpredictable noise was the audio pot itself. It had poor mechanical connections between the input leads and and the internal traces that go to the resistor and wiper. They were actually wiggling around and constantly disconnecting and reconnecting randomly. I took it apart, cleaned the wiper with some rubbing alcohol, tried to get a better connection on the inputs by crimping them down and putting some solder on them, and then put it back together. Once I put that back into the circuit, it was still humming at high volume settings, but much more predictably. I also cut off the unused center tap lead on the primary side of my audio transformer. That wasn’t the source of the problem, but it wasn’t helping things. Finally, I put a 470u cap from the power rail to ground. That doesn’t totally eliminate the hum, but along with the other changes, it reduces it enough that nearly all of the volume range is reliably usable. It will still hum if I turn it all the way up, or if there is no antenna plugged in, but I think it is working in ordinary circumstances.

Congratulations David.

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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:

Ben KC9DLM’s SolderSmoke Direct Conversion Receiver

Ben had to overcome some antenna problems, but as you can see here, he got it going.

He also had to overcome a capacitor shortage. He did it, using parts on hand. FB. Ben writes:

I forgot to order the 470uF caps for the audio stage, so I used some amusingly large 220uF I had in parallel.

Thanks Ben. Congratulations. 73 Bill

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:

Scott K1OA FB SolderSmoke Direct Conversion Receiver

Scott K1OA has been a licensed ham for more than 50 years, but he tells us that this was his first Manhattan-style project. He reports having built a lot of kits and even a DC receiver from EMRFD using an SA602 chip, but he says the SolderSmoke direct conversion receiver was the most fun. That comment meant a lot to us. We continue to believe there is value in homebrewing from scratch.

Scott writes:

Hi Bill,


This will be my 50th year as a licensed ham and my first

Manhattan style project. I’ve built a dozen kits in the past

15 years or so and bread-boarded a simple crystal

controlled DCR from a circuit in EMRFD

using an SA602, but the Soldersmoke DCR

challenge has been the most fun!


The most challenging aspect has been trying to get the

PTO tuning range close to 7-7.3 MHz. I’m still

experimenting with that.Audio output is loud and

sensitivity is pretty good.


I’m thinking my next project might be a simple crystal

controlled CW transmitter to pair up with the DCR, and

considering the Pebble Crusher 1/2W design from the

ARRL Handbook that uses a pair of 2N2222A

transistors. I’m interested in your thoughts on that.


Thanks for putting forth the challenge and for all the

great support you and Dean have provided!


73,

Scott K1OA


p.s. – love the podcast and your Soldersmoke Adventures

book!

Thanks Scott and congratulations.
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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:

Juan LU2VJM’s Beautiful Argentine SolderSmoke Direct Conversion Receiver

I was really pleased to see Juan LU2VJM’s rapid completion of the SolderSmoke direct conversion receiver. But I wasn’t really surprised — Juan is an experienced homebrewer who has successfully completed Farhan’s BITX transceiver. Juan and I talked about how it is worthwhile for even an experienced homebrewer to go back and build a direct conversion receiver. Farhan did this. Farhan said that we do this because we are tool makers. We have opposing thumbs that allow us to grab a soldering iron. Indeed. And you can hear the happiness in Juan’s voice when he says in the video, “Today we have reception!” Excellent.

I was also pleased to see this receiver enter the Hall of Fame becasue this marks our first receiver from Latin America. We hope there will be many more.

Here are some pictures of Juan’s receiver during construction:

Juan’s AF Amplifier

Juan’s Diplexer with homebrewed coil

Another shot of the AF amplifier

The mixer, getting ready for construction

The completed receiver. FB!

Thanks Juan! And congrastulations!


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:

Garry’s FB Australian SolderSmoke Direct Conversion Receiver with “Free Tree Printed” PTO Coil Form

Garry built a really nice receiver. I think he is in Australia. His PTO coil form is “a piece off an old rotten Australian red cedar door.” FB Garry.

Garry did a really nice blog entry on his build experience:
As with Chris, if there was any justice in the world, Garry would be issued a ham license based solely on this receiver build. He has done something that 95% of hams have never done: he built a receiver!

Congratulations Garry!

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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:

Dallas KC5DI’s SolderSmoke Direct Conversion Receiver

Dallas is a friend of Lyle WZ5M — Lyle encouraged him to build this receiver. Dallas’s son is also working on a receiver — we hope to see that one completed soon.

FB Dallas and congratulations.

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:

Lyle WZ5M’s SolderSmoke Direct Conversion Receiver

Lyle WZ5M did a great job on his receiver, and in the finest ham radio tradition encouraged two other builders to take up the SolderSmoke challenge. FB Lyle. I really like your receiver. That looks like a genuine pine board. Frank Jones would approve.

73 and congratulations!

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:

Jim K1KJW’s SolderSmoke Direct Conversion Receiver

Jim’s Vermont DC receiver is really nice. It is pulling in the 40 meter CW very well. Check out Jim’s QRZ page: https://www.qrz.com/db/K1KJW

Thanks Jim and congratulations.

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:

Jim K1KJW’s SolderSmoke Direct Conversion Receiver

Jim’s Vermont DC receiver is really nice. It is pulling in the 40 meter CW very well. Check out Jim’s QRZ page: https://www.qrz.com/db/K1KJW

Thanks Jim and congratulations.

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:

John KC9OJV’s SolderSmoke Direct Conversion Receiver — John Becomes a Manhattan-Style Convert

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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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:

Honorable Mention: Bruce KC1FSZ’s SolderSmoke Direct Conversion Receiver ON A PRINTED CIRCUIT BOARD

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.

Thanks Bruce! Congratulations! 73 Bill Hi7/N2CQR

Jerry AA1OF’s SolderSmoke Direct Conversion Receiver

It was a long hard struggle for Jer, but he hung in there and got it done. Congratulations Jer.

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:


Honorable Mention: Steve AA7U’s Dead-Bug Direct Conversion Receiver

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.

Here’s one eBay seller of the inexpensive audio transformers I used
https://www.ebay.com/itm/356127836595

(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.)

73,

Steve AA7U

Thanks Steve and ongratulations!

Karl K5KHK’s, Junkbox (but really nice) Direct Conversion Receiver (with a rebuilt AF Amp)

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.

Thanks Karl, and congratulations!

Honorable Mention: VK7IAN’s Tasmanian Direct Conversion Receiver

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

Bill AB5XQ’s “Ugly Duckling” (Not true!) SolderSmoke Direct Conversion 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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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:

Roy WN3F’s FB SolderSmoke Direct Conversion Receiver

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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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:

Adam AA1N’s SolderSmoke Direct Conversion Receiver

Adam built a fine receiver.

Abam wrote:

Thanks Bill! And 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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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:


Nate KA1MUQ’s Frying Pan SolderSmoke Direct Conversion Receiver

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:

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:

Piotr KD9NHZ’s SolderSmoke Direct Conversion 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:

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: