CuriousMarc Gets an Apollo DSKY Running. FPGA AGC Computer. Rope Memory.

I really liked this video.  So much amazing wizardry in it.  Just the FPGA Apollo AGC simulator that Mike whipped up.  Wow.  Kudos!  

Their occassional references to "rope" brought back fond memories of "Sunburst and Luminary" by Don Eyles:  https://soldersmoke.blogspot.com/search?q=Apollo+rope 

Victor's FB SolderSmoke Direct Conversion Receiver from Holland Pulls In Stations from All Over Europe... and One from Japan

Victor is a retired Electrical Engineer from the Netherlands.  He doesn't have a ham radio call sign, but as I have said about other receiver builders, he deserves one.   Note the truly homebrew approach that Victor used on the PTO coil form.  And he had to rebuild this part to get the receiver on 40 meters.  As we can see in the above video, Victor's homebrew receiver is pulling in stations from across Europe.  Victor even reports hearing a Japanese station.  FB! 

Victor writes:

Hi Bill, I changed the PTO tuning unit, more stable this way.   I m a retired electrical engineer, revamping on a more daily basis  tube radios from the 50's 😉 I include a Bluetooth interface too so they can be used again by "young" people with their smartphones..  I had great fun and learning experiences building the DCR !!  

Thanks for the video, pictures, and messages Victor.  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:

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

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: 

https://garrysblog.com/2025/03/14/my-build-of-the-soldersmoke-40m-direct-conversion-receiver/

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:

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

 

Tapesponding -- Who Knew?

I didn't realize that "tapesponding" had become so widespread.  I know of two very prominent homebrewers (one now a Silent Key) who exchanged tapes.  When I learned of this I asked if those tapes (which would have been a real treasure) were still around.  Sadly, they had been destroyed,  as, I suspect, were most of the tapes mentioned in this video. 

I sometimes think that some of the on-the-air conversations about tech topics really should be saved for posterity (most conversations clearly should NOT be saved!).  The internet provides a great forum for this kind of preservation.  This happens,  but only very sporadically and mostly in the AM world. 

Thanks to Hack-A-Day for alerting us to this. 

Nate KA1MUQ Turns His Frying Pan DC Receiver into a Double Sideband Transceiver and Works Idaho from California

Wow, you can see the look of homebrew satisfaction as Nate works Idaho from California with his homebrew Double Sideband Transceiver.  It is a good thing that Nate got that frying pan into the shack before he was banned from the kitchen. 

Nate writes: 

I finally got my DCR to be a DSB transceiver.  I had a lot of trouble with transmitted RF getting back in to the VFO and causing distortion.   While I imagine I could have tried putting the VFO in metal box, I instead opted to move the VFO to a 4.7-5 MHz range and then mix that with a 12 MHz crystal oscillator.  Now the VFO is at a frequency unaffected by transmit RF.  This mixer and crystal oscillator are on the breadboard and from SSDRA.  The transmit amplifier chain was taken from Fahran's Daylight Again radio.   I just got a 570 mile contact on 5 watts - conditions are good.   If there is interest let me know and I'll share my schematic.

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I looked this morning and I have 100 DSB posts on the SolderSmoke blog.  There are lots of ideas there on how to homebrew for DSB, many of them from Cuba, many covering DSB rigs that I built in the Azores, and others that I used in the Dominican Republic.  Check it out: 

https://soldersmoke.blogspot.com/search/label/DSB

 

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:

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

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:

https://www.youtube.com/@soldersmoke 

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:

https://www.youtube.com/@soldersmoke 

Homebrew Challenges Much Like Ours: The Direct Conversion Receiver of Wes Hayward W7ZOI and Dick Bingham W7WKR -- QST November 1968

 

https://www.worldradiohistory.com/Archive-DX/QST/60s/QST-1968-11.pdf

I was thinking about some of the challenges faced by the builders of the SolderSmoke Direct Conversion Challenge Receiver, and about how similar these challenges are to those described by Wes Hayward W7ZOI and Dick Bingham W7WKR in the November 1968 QST article that launched the direct conversion revolution among radio amateurs. You can read the full article beginning on page 15 in the link above.

Some observations and comparisons:    

--The November 1968 QST article said, "This receiver was designed for simplicity and ease of duplication, rather than ultimate performance."  Ours too! 

-- Wes's receiver has a single tuned circuit in the BP filter.  Ours has two LC circuits. 

-- Wes's mixer is also a diode ring.  He starts out using hot carrier (Shotkey) diodes, but later concludes that ordinary diodes would work just fine.  We reached a similar conclusion.  But I wonder if the ordinary diodes would work well with a low output level from the single FET VFO (see below). 

-- His oscillator uses a single MPF-102 in a Hartley configuration with no voltage regulation, and no buffer.  We have two active devices and a Zener diode.  This article makes me think we could have made our PTO even simpler.  

-- Wes's receiver has a low-pass filter between the mixer and the AF amp.  The cutoff is at around 2 kHz.  This seems quite low in frequency and may reflect a preference for CW.  It features 88 mH coils that are now quite hard to find. The goal of this filter seems to be to prevent signals from beyond the audible frequency range from overloading the AF amp.  We ended up using the diplexer from the W7EL optimized QRP rig.  I think this diplexer takes care of the problem.  

-- The W7ZOI/W7WKR receiver has no AF nor RF gain control.  When encountering a strong SSB signals, the article recommends detuning the BP filter.  I think our AF gain control, and the mod calling for an RF gain control will give the operator, well, more control and will prevent strong SSB signals from overloading the AF amplifiers.  The RF gain pot might also help prevent SW broadcast AM breathrough. 

-- One big difference between our receiver and the November 1968 QST receiver:  isolation of the VFO.  The QST article puts the VFO in an aluminum box above the chassis.  We have the PTO without any shielding right alongside the other circuits.  Builders might want to experiment with the kind of isolation recommended by the QST article.  Would this kind of isolation and shielding improve performance? 

-- Wes also obviously contended with oscillation by the AF amplifier, as did many of our builders.  The QST article contains a number of recommendations: First test the amplifier to see if you can hear noise.  If it oscillates, try increasing the value of the decoupling resistors. (Many of our builders added electolytic caps to the DC power line in the AF amp.)  The article recommends trying a .01uF cap across the output.  It also recommends keeping the output of the amplifier away from the low pass filter at the input.  Wes's design has no transformer as it makes use of high Z headphones. 

-- The QST article says that the product detector performed adequetly with an LO injection level of .6 volts peak-to-peak.  This seems quite low to me,  but perhaps this would work with hot carrier diodes in the diode ring?    This might be one good reason to use diodes that have a lower turn-on voltage -- you could get away with using a super-simple VFO even if it provides lwer voltages to the mixer.  It might be fun to experiment in this area.  

As readers can see, the challenges faced by the builders of the SolderSmoke DC receiver were very similar to those face by the builders of  the November 1968 machine.  I think all of us should find this very encouraging.  

Thanks again Wes and Dick. 

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! 

--------------------

 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: 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:

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