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:

https://www.youtube.com/@soldersmoke 

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! 

Honorable Mention: Karl K5KHK's Rebellious, Junkbox (but really nice) Direct Conversion Receiver

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 "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.  

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

Andy KB7ZUT is a Good Sport -- He Built the Direct Conversion Receiver HIS WAY, then OUR WAY. Great StarTrek Cartoons

 

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: 

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:

https://www.youtube.com/@soldersmoke 

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:

https://www.youtube.com/@soldersmoke 

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:

https://www.youtube.com/@soldersmoke 

Adam AA1N's SolderSmoke Direct Conversion Receiver

Adam built a fine receiver. 

Abam wrote:  

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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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:

https://www.youtube.com/@soldersmoke 

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:

https://www.youtube.com/@soldersmoke 

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:

https://www.youtube.com/@soldersmoke 

Steve N9SZ's FB SolderSmoke Direct Conversion Receiver

FB Steve! Your receiver looks and sounds great!  Congratulations!   

Steve writes:  

Thanks to Bill and Dean for all their work and promotion of this project. I learned alot and had fun. The receiver works well now after much tweaking. I need to finalize how the boards will be mounted. I am thinking of mounting the BPF and audio amp boards vertically on the edge of my small piece of wood and create a front panel using a PCB to mount a on-off switch, volume control. on/off LED, and the speaker/headphone jack. I also want to add a rear PCB to hold an antenna jack and power jack.

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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:

https://www.youtube.com/@soldersmoke 

Martin GM5JDG's SolderSmoke Direct Conversion Receiver Inhales on SSB Contest Weekend

When I first saw Martin's boards, I thought I was looking at something that was not really Manhattan style.  But I was wrong -- Martin had simply drawn grid squares on his boards.  He used MeSquares for his non-ground connections.  The SSB his receiver was picking up sounded great.  

Martin is a relatively new ham -- he started in 2020.  It is really nice to have Scotland represented in the group.  

Martin writes:  One of the main things I learned was how to really start to use my oscilloscope. The band pass filter proved to be challenging as I initially placed my trimmers incorrectly and it took quite a while to find the problem. I'm looking at this as a potential high school project, so all my soldering was with lead free solder, as I run a community interest company providing tech workshops for disadvantaged kids. I would like next to look at building a complimentary transmitter. Will also have a look at the mods and upgrades.

Martin has noted the touchiness of the main tuning knob.  One of the mods he should look at is the one that allows for easier tuning across the 40 meter band.  It is described in detail in a post on mods-and-modifications. 

Thanks Martin, 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:

https://www.youtube.com/@soldersmoke