Brian KI7LKB's SolderSmoke Direct Conversion Receiver with a FB Unique PTO Coil form Using a Coat Hanger Tube!

Brian KI7LKB has built a very FB SolderSmoke direct conversion receiver.  He made the PTO coil form himself, using the cardboard from a coat hanger as the tube. (I have used these tubes for many homebrew inductors.  I thought I was alone!  FB Brian.)  In the video above we see Brian's receiver pulling in SSB signals. 

Brian writes: 

Finished the DCR! Even with S-7 noise, from here in Southern Nevada, picked up stations in Canada, Texas and Louisiana. Built to plans, except the PTO coil form was fabricated from a clothes hanger tube mounted in a fiberglass frame. Antenna is an inverted “V”. A ham since 2017, I’m always looking for something to build, and the Soldersmoke podcast provided an educational and appropriately challenging project. I particularly like the fact it is modular, and I’ve already identified other applications for the audio amplifier. Your guidance was excellent and I learned a bunch. Thank you!

Here is Brian's receiver at work in the CW portion of 40 meters: 

Thank you Brian.  Congratulations!  You homebrewed a receiver! 

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

Mikael SM0TPW's FB SolderSmoke Direct Conversion Receiver from Sweden

 I was very pleased to see Mikael's video.  This is our first receiver from Sweden.  In his QRZ page Mikael talks of learning CW while in the military, and of making a few contacts with the equpment of his regiment.  I had a similar experience -- I once made a CW contact with the rig assigned to our team.  

Mikael writes: 

Thank you Bill.

I’ve been a Ham for 35 years with a long gap in the middle of 20+.

I am of course a Soldersmoke listener and tried to build this dcr when you built it in the highschool project, but I didn’t succeed that time and gave up.

But with all the guidance here on discord I gave it one more go, and succeeded. 😊

The hardest thing was, as for many other, the af stage and oscillation. But some bypass caps and problem solved.

I got so much help just reading all posts here so thank you all in this community!

Now I will lean back for a while and listen to my baby. I am a proud father right now.

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Indeed Mikael, that is what Farhan advises:  sit back and enjoy the receiver that you have built.  Congratulations!  The receiver sounds great on CW and on SSB.  

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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

Checking in to the Old Military Radio Net, March 29, 2025

This was a fairly typical session of the Old Military Radio Net. 3885 kHz AM 0500 local on Saturday mornings. (Distant listeners can tune in via WebSDR.) This clip shows W3EMD, N2CQR (me) and, N1SNG. Buzz W3EMD from the Hudson Valley of New York was on with his KWM-1. Normally he uses a BC-348 powered with a Dynamotor. Last week he told the group that someone had COMPLAINED about the noise that his mic was picking up from the Dynamotor. Geez! I told Buzz that we had been commiserating with him about this on the SolderSmoke podcast. Later in this morning's session I heard WU2D, WA1HLR, AJ1G, and others. I reported on an emergency De-Oxit spraying of my HQ-100's band switch, just minutes before net call up. I also noted that I had found a crystal for 3885 kHz; the radio gods have spoken (TRGHS).

The MakeIt Labs of Nashua, New Hampshire -- Four Successful Direct Conversion Builds

 

This picture came in on February 27, 2025 from Nashua, N.H. 

On February 27, 2025 they wrote:

 Hello from MakeIt Labs (a makerspace in Nashua, NH, USA).  Andy (KB1OIQ), Jay (KA1PQK), Mike (W1TKO) and Wayne (KC1ONM) are building the DCR as a Tuesday Night Project Night activity.  This week we all experienced the joy of oscillation 😂

On March 27, 2025 all four builders completed their projects, submitted "proof of life" videos, and entered the Hall of Fame.  

And it looks like they had a lot of fun.  That MakeIt Lab looks like a great way to pull people together for projects like this.  Well done guys!  Thanks and 73! 

Mike W1TKO's Beautiful SolderSmoke Direct Conversion Receiver

Mike W1TKO is a realtively new ham, getting his ticket in 2022.  But he has already done something that 95% of all hams never do:  He has homebrewed a receiver.  The personalization of the receiver adds a nice touch of class to the project.  FB Mike.  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

Jay KA1PQK's Wonderful SolderSmoke Direct Conversion Receiver

On Jay KA1PQK's  QRZ page he says that he has long been interested in the minimalist side of ham radio.  This project certainly fits in with that, but there is noting minimalist about the satisfaction that we can seeon Jay's face as he tunes the receiver that he hombrewed himself.  FB Jay.  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

Andy KB1OIQ's FB SolderSmoke Direct Conversion Receiver

Andy has a lot of homebrew projects underway, but I think this one must have been the most rewarding.  He has done something that 95% of hams never do:  He has homebrewed a receiver.  Congratulations Andy!

Check out Andy's presentation on Linux to the 2025 Dayton Hamvention: 

https://www.youtube.com/watch?v=q1wKQBWkUnY

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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

Wayne KC1ONM's FB SolderSmoke Direct Conversion Receiver

Wayne KC1ONM built a very nice direct conversion receiver.  He has done something that 95% of hams never do:  He has HOMEBREWED a receiver.  FB Wayne.  Congratulations!  

After his completion of the receiver, Wayne put it all in a beautiful homebrew case: 

To mark the PC boards, Wayne says, "MakeIt Labs has a MOPA laser. They were marked after construction of the board (the focus is high enough not to interfere with the components), but before attaching them to the box."

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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

Dave G6GEV's Very FB SolderSmoke Direct Conversion Receiver, with an Innovative Bic Pen PTO!

This is a really nice one.  In the "proof of life" video we find a lot of proof, and a lot of life.   SSB from the UK sounds really good.  This is one of the beauties of the Direct Conversion architecture -- you end up with a receiver that sounds very good.  Doug DeMaw said these receivers have "presence" -- it sounds like the other fellow is present in the room with you.  

Dave's happiness and satisfaction really shines through in his comments. Dave writes:  

I've just completed my DCR, and it's been an absolute blast!

I'm a retired EE, where PCBs and surface-mount components are the norm. I've occasionally prototyped using dead bug or Vero-board, but this is my first exposure to Manhattan construction - and I've thoroughly enjoyed it. Electronics and radio were my childhood passions, but inevitably, they lost some of their appeal once they became a career. Thank you, Bill and Dean, for helping me regain some of that lost joy!

My biggest challenge was trying to locate parts from a single UK source to minimize shipping costs (yes, I'm cheap). I briefly contemplated building a push-pull audio amp to avoid purchasing the transformer from Mouser, but in the end, I found most parts there, then padded the order with common junkbox parts to get free shipping. I'm so pleased that I heeded Bill and Dean's advice to build the receiver as presented (well, almost). The results are so much better than I expected, with great-sounding, room-filling audio when connected to the passive half of an old active stereo speaker pair. Tuning is a bit fiddly but improves with practice. Luckily, I had no problems with any of the stages, and it just worked when the boards finally came together. 

To save money (did I mention that I'm cheap?), I decided to use NP0 capacitors in the PTO instead of silver mica. The thermal coefficient should be similar, and if they didn't work out, I planned to swap to mica later on. It turns out NP0 works great for me, with no noticeable drift after several minutes.

I don't have easy access to a 3D printer, so I decided to roll my own PTO former. I wound the coil on a Bic Biro with a layer of heat-shrink tubing to bring the diameter to 10mm. This was glued to a wooden support, and the M6 threaded brass bar was a perfect fit inside the Biro. I finished it off with a tuning knob made from an old RC aircraft prop spinner. After experimenting with coil spacing, I ended up with wide spacing under the actively tuned area of the coil and tight spacing at the other end. This reduced the tuning sensitivity, and I now get around 40 kHz per revolution.

I'd really like to make a home-brew 2-way contact with this receiver, so maybe I'll try a DSB transmitter next...

Thanks again to Bill and Dean for providing this fantastic resource. I've been a SolderSmoke listener since episode #1, and after 20 years of constructing radios vicariously, I've finally built one myself!

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FB Dave!  Thanks 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  

SolderSmoke Podcast #258 -- Travelogue, SDR, Direct Conversion Receiver Project, Homebrew HDR SSB, Mailbag

Falcon 9  from our apartment in Cap Cana DR

SolderSmoke Podcast #258 is available: 

Video Version:  https://www.youtube.com/watch?v=75ewswI7CcA

Audio Version:  http://soldersmoke.com/soldersmoke258.mp3

Travelogue:  I am back from the DR. Trying to get a real HI7 call.  Lots of science and nature: Earthquake (5.9) . Falcon 9.  But no Starship.  Two possible Starlink de-orbits. Whales.  Hawks.  A drone. (Pictures on Patreon.)  A total lunar eclipse. A 10 meter CW beacon, with an LED, thanks to WN2A.   Lots of great people. But it is good to be back.  Planning for a better antenna for DR. 

Pete's bench:  Pete is building a seismograph! CL Stong had several in his book "The Amateur Scientist." The MHST.   Help from Oliver KI3P of VWS. 

Shameless Commerce Division:  Please continue to use the Amazon link on the right.  Mostly DIY RF!  Link on the blog page. And please become a Patreon sponsor.   People have asked, what is happening to the blog and podcast.  Well, listen to this one for a sobering description of what is happening on the internet to things like SolderSmoke: https://share.fireside.fm/episode/2YAGasSP+_rbTJaWN  Patreon might be the answer for us too.

 

Dean/Bill:  Lessons learned from the SolderSmoke Direct Conversion Receiver Build project: -- 45 successful builds!  Wow.  See: https://soldersmoke.blogspot.com/search/label/DC%20RX%20Hall%20of%20Fame -- Differences between kit-build and true homebrew. -- Discord, Questions, Mods, Creativity vs. Build it our way the first time.  Dean and the trials and tribulations of being the electronic problem go-to-guy.  HRWB (what happened?)  We used copper clad boards and Manhattan technique with no fatalities.  DSB TX seems the most popular next step -- some have already been done. 

Dean's Bench:  The VWS SDR receiver build.  The 20 meter Yaesu VFO transceiver build (ANOTHER one?).  Why is this Yaesu VFO different?  Filter building   Balloons! 

Bill's Bench:  Checking into "The Old Military Radio Net."  South Pacific and Australia on 20 SSB in the morning.  Approaching "Worked all Rarotonga." Makes me think I need a directional antenna for the DR...   Beacon left on in the DR.  A 10 meter AM QSO using the converted GE rig. G3YPZ!   Dean has the JC Penny.  Hamfest report heard on the OMRN: DX60s stacked like cordwood.  Buy one and get one free.  

MAILBAG: 

Bob:  Software for SSB on the QMX. 

Roy WN3F new stickers

Rogier PA1ZZ-  Capacitors replace batteries in French electric bikes. 

Walter KA4KXX -- Lots of help on the DC RX project

Aaron ZL1AUN  Doing an article for Break-in (NZ) about the DC RX

Farhan  VU2ESE  On DC RX:  "They have mastered the Alchemy of turning lifeless components into living and breathing radios. May the tribe grow!"

Ramakrishnan VU2JXN -- We need an Indian DC receiver Ramakrishnan! 

Grayson KJ7UM -- Discord gang discovering Hollow State Design for the Radio Amateur 

Mike WN2A Sent keyer for beacon and good advice on diplexer. 

Alan W2AEW    JOO, but we are hoping for more! 

Mike WU2D  FT-101 videos. Son is making coils! https://www.ebay.com/usr/blakertree

Buzz W3EMD  One guy complained of the noise of his Dynamotor.  Pete knows a guy... 

Dave W2DAB  We NEED an upper east side DC Receiver 

Phil W1PJE   We need an MIT DC receiver. But we understand the delay. 

Wes W7ZOI  A nice email from Wes. 

Jeff WA7MLH  Homebrewing and the number of homebrewers. 

Dave AA7EE put a nice comment out about Armand WA1UQO's regen. 

Sticker by Roy WN3F

Forbidden Workshop Practices -- Part 2 -- By Van Neistat

The image I had for Part 1 was frighteningly large, so I made it smaller.  

I know this is controversial (!) but I share Van's aversion to flat head screws.  

Becoming a hoarder is a real danger that we all face. Be careful out there! 

Honorable Mention: Graham CT7AXD's Reassembled SolderSmoke Direct Conversion Receiver

Graham was another good sport.  When I asked him about the receiver, he had already moved on, and -- is often happens -- had separated the stages and replaced some of them.  He agreed to put the receiver back together and to shoot a video of it in action.  Above you can see it, happily inhaling SSB from nearby Spain. He used a different AF amplifier cicruit -- that is why this is in the Honorable Mention catergory.  

Graham writes: 

It has been an interesting exercise as I've tended to use active mixers before, but I think I am converted to DBMs now. The other rx I've been working on with a VCO is performing very well. I need to move the preamp over to the PTO one and see how it performs.

Thanks Graham 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

Forbidden Workshop Practices Part 1 -- By Van Neistat

 

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:

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

The Electrolytic Capacitor Plague

So, what caused it?  Maybe a variety of factors?  Perhaps different factors explain different circuit failures?  The video, for example, focuses on CPUs that drew a lot of current and got real hot.  OK, but we also see failing electrolytics in small, very low current Sony receivers.  

Hack-A-Day has a good post about this:

https://hackaday.com/2025/03/18/the-capacitor-plague-of-the-early-2000s/#more-767835 

The Hack-A-Day comments are also (mostly) good.  I agree with the fellow who said he never heard anyone call electrolytic capacitors "E capacitors."  Me neither.  

Lex PH2LB's Fantastic, 3-D Yellow, Glue-Stick, SolderSmoke Direct Conversion Receiver from the Netherlands

Lex PH2LB has been a valued member of the SolderSmoke team for a long time.  It was he who took our stickers into the bars and coffee shops of Holland, spearheading our efforts on Continental Europe.

He didn't have to, but Lex took up the SolderSmoke Challenge.  And he did it with panache.  3D yellow panache.  Glue-stick panache!     

Lex has a complete description of his build here: 

https://www.ph2lb.nl/blog/index.php?page=soldersmoke-dcr

Here is another video of Lex's receiver in action 

Indeed, it is working!

Bravo Lex.  Thank you 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

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:

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

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:

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