Joe N90K's FB SolderSmoke Direct Conversion Receiver

Congratulations to Joe N9OK on his homebrew build of the SolderSmoke direct conversion receiver. Welcome to the Hall of Fame Joe.  

Joe makes some very nice comments on the benefits of doing this in a homebrew way:  

I've build many dozens kits over the years, esp Knight, Heath, K2, K3, and others. This was my first receiver built from scratch. It works surprisingly well and has decent sensitivity. Thanks @Bill N2CQR and Dean @Soldersmoke for creating this challenge. It was fun and non-trivial. The only stage I had issues with was the amplifier, which was too compact on v1. v2 works well.

I think Joe should hold onto that smaller version of the AF amp. I think he could get that stablized and it could become the heart of yet another FB DC RX.

Joe went the extra mile and measured the minimum discenable signal of the receiver:

 

I see no problem with Joe's measurment technique.  I think the key word here is "discernible."  Often people will focus on the RF signal that will produce a 3 db or 10 db increase in audio signal.  But Joe has just looked at the RF signal level that will create a discernible audio signal.  That is fine.  As Joe demonstrates, this simple DC receiver is remarkably sensitive.  

Ham Radio Ireland Magazine available for free download

I was recently talking on 17 meters to my good friend Mike EIOCL.  He mentioned that Steve Wright EI5DD had put out new editions of Ham Radio Ireland -- a very FB publication.  This morning a message from Steve showed up in one of my e-mail accounts: 

Hi,

 

Here is the link to the latest August 2025 issue of Ham Radio Ireland Magazine, A free publication downloadable from the following link in PDF Format https://docdro.id/Hg8uxRx

 

 

Recently we introduced the facility of an Online FlipBook which enables you to turn the pages on Screen.

 

Here is the link to the FlipBook https://heyzine.com/flip-book/7b84284360.html

 

Once the link opens there is a box at the top right-hand corner which will enable enlargement and clicking on the Cloud Icon will allow the PDF to be downloaded. There is even a share facility.

 

If you have enjoyed our magazine, please share on social media or distribute around you club members as this will increase our circulation.

 

If you are a Secretary of a club do feel free to send us information about your planned activities and we will include them in our news section. It is free publicity.

 

Steve EI5DD Editor

John EI3HQB Sub Editor

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

Check it out!  Thanks Steve and John.  And thank you Mike! 

The Decline in Quality

"Artificial intelligence itself could deteriorate if no action is taken. In 2024, bot activity accounted for almost half of internet traffic. This poses a serious problem: language models are trained with data pulled from the web. When these models begin to be fed with information they themselves have generated, it leads to a so-called “model collapse.” "

https://english.elpais.com/culture/2025-07-20/the-bewildering-phenomenon-of-declining-quality.html

The Red-Shifted Neutral Hydrogen Signal from the Cosmic Dark Ages is in the Range of our Direct Conversion Receiver

On the flight to the Dominican Republic I was listening to Fraser Cain's interview with Dr. Christiaan Brinkerink.   I was kind of blown away when they started talking about where the neutral Hydrogen signal would be NOW, after the all of the cosmological red shift.  Asked this question, Christiaan kind of casually responds that it would be "just above 7 MHz."  He talks about this at 41 minutes and 41 seconds in the video above.  He points out that this represents a redshift of about 200.   Wow, that is just where our SolderSmoke Direct Conversion receivers tune, and where their PTO/VFOs operate.  And we thought Radio Marti was a factor to consider!   No wonder Christiaan and his colleagues want to go to the far-side of the moon.  They want to get above the ionosphere, but they also want to get the shielding provided by the moon to protect them, I suppose, from signals like those being produced by the 40 meter ham band, and, (to a lesser extent) by devices like our little oscillator. 

You can watch Fraser's interview with Christiaan above.  It is really interesting and inspirational.  Christiaan talks about dipole arrays, RFI, interferometers, sensitivity, signals of "several kHz" in width, dynamic range, and other topics known to us.  Christiaan is an "Instrument Systems Engineer" at Radboud University.  I think he deserves a ham radio license.  Maybe he should build a SolderSmoke Direct Conversion receiver.  Fraser should build one too.  

Here are a couple of links to articles about this: 

https://www.universetoday.com/articles/observing-the-dark-ages-of-the-universe-from-the-far-side-of-the-moon

https://pmc.ncbi.nlm.nih.gov/articles/PMC10961189/

Thank you Fraser and Christiaan. 

Fritz's FB SolderSmoke Direct Conversion Receiver

Fritz did an excellent job on his build of the SolderSmoke Direct Conversion receiver.  Fritz writes: 

Hi folks!  First-time radio builder here, and I've just completed my DCR build! (Pic and video below...)

I have a background in electronics, but mostly audio, digital, video games, tube guitar amps, etc.  My only previous experience with radio was a restoration of a small AA5-style radio for a friend.  I first saw this project featured on w2aew's site and it seemed too fun not to try.  First go with Manhattan construction, too, and I really enjoyed it!

Though I built everything on one board, I did test the modules one by one as I went.  I did build and test the audio amp "left to right" instead of the other way around, because I have enough bench gear that I could check as I went without relying on the speaker. 

My audio amp build did tend to motorboat turned about half-way up, particularly with no RF input.  It was easy to see on the 'scope that the DC power bus was the feedback path.  Threw a couple 470uF on there and that pretty well quenched it.  In addition to the coil former, I also 3d printed a battery clip and and bracket for the volume pot.

Tuning turned out to be pretty delicate/twitchy, but I am getting better at it.  I opted to start with the 28 TPI steel screw after reading some things on the blog.  I will probably end up moving some of the windings off the tuning former to try and improve this, and/or investigate a fine tuning option.

I am running right now with a 33' wire out my basement window, up the side of the house, and partway across my flat roof, plus a 16' counterpoise on the basement floor.  Will probably get more ambitious with a feedline to a vertical wire in a tall tree in the backyard away from the house this upcoming week.

No license or callsign yet, but I've definitely got the bug with this project, so am reading the materials and hope to take the exam(s) soon!

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Congratulations Frtiz -- Welcome to the Hall of Fame! 

Britain's EF-50 Valve (Tube, Thermatron) in WWII

Thanks to Rogier PA1ZZ for sending us this. 

Looking for a Web Person to Create a WordPress Staging/Backup site for this blog.

I can supply the backup files and the Template backup.  I need someone who can create a backup site for this blog.   I think it should be in WordPress.  It should include all the posts and comments, pictures and videos in the current blog.  It would be great if it used the same Template as the current blog.  I want to keep the current blog going indefinitelty, but we need a backup site that could be used if Google suddenly decides to "deprecate" blogspot. 

Please let me know if you can help or if you know someone who can.  We will pay.  We can discuss this before any work begins.  

Thanks.  73  Bill

A USB-powered Homebrew X-ray machine. And who is Project 326?

This is an interesting project.  The use of dental X-ray packs was really innovative. The approporately snarky presentation about nanny-state nervous nellies was great.  It all reminded me the X-ray chapter of C.L. Stong's great book "The Amateur Scientist."   Here is a .pdf of the book:  http://www.ke5fx.com/stong.pdf

The X-Ray machine in Stong's book appears on page 500 (520 in the .pdf)  Here is the opening paragraphs:  

Indeed, it was lonely up there in the 10^-8 cm band! 

But who is behind Project 326?  Who is the robot narrator's human assistant?  At first I thought they were joking when they said they were in Southern China.  But YouTube does show them in Hong Kong.   He has British accent, but oddly he calls valves "tubes."  He also seems to use quite a bit of SolderSmoke terminology and practice:  He uses copper tape as a ground plane. He talks about relaeasing "Magic Smoke" and of passing or failing "the smoke test."  Could it be that Project 326 had been listening to the SolderSmoke podcast?  We hope so!   Please let us know if y ou have any background info on this mad amateur scientist. 

Here is the Project 326 YouTube channel:  

https://www.youtube.com/@project-326

How many of you guys have changed the clutch on a Heathkit HW-101 (or similar rig)?

That circular thing on the right is the "Plastic Clutch" on the Heathkit HW-101.   Mine dried out and shattered when I pushed the "Zero Set" button on the from ot the HW-101.  I heard it crack.  I cut out a piece of plastic of the right size.  That replacement clutch has been in there for about 30 years now.  

I know of one other guy who has replaced the clutch on a HW-101 (Will, N5OLA).  Let us know if you have done this too.  Put a comment down below. 

Oscillation! Negative Resistance! Barkhausen Explained Very Well!

It is not every day that we find a web site or a YouTube video that discusses negative resistance and the Barkhausen criteria.  But that day has arrived my friends!  

This All Electronics fellow appears to be Italian.  I really like his enthusiasm. The universe!  Differential equations! The passion seems to jump out of the video when he talks about how the negative resistance "enhances the oscillation!"  It is really great.

He even talks about how thermal noise gets the oscillation going.  This is something that I struggled with as a kid.  It took me a while to find a good source that explained this.  He explains it very well. 

Thanks to master homebrewer Pete Juliano (another Italian!) for alerting us many years ago to the Barkhausen criteria.  And thanks to Al Williams at Hack-A-Day for alerting us to this great video. 

Here is the All Electronics channel on YouTube:  https://www.youtube.com/@AllElectronicsChannel

Dan KF5DAN's FB SolderSmoke Direct Conversion Receiver

It is a happy occassion whenever we get to announce a new member of the SolderSmoke Direct Conversion Receiver Hall of Fame.  And Dan KF5DAN has entered the hallowed halls.   Congratulations Dan.  We are really glad you are doing the happy dance.   Above you can see Dan's receiver inhaling SSB, in the video below you see it receiving CW. 

Dan writes: 

I would like to present proof of life! I found the motorboating issue in my amplifier. R18, 1K resistor was connected from the power rail to the base of Q5, instead of the collector. I moved it, and had already added a 470uF cap from earlier troubleshooting. There is a lot of noise, probably due to some stormy weather in Arkansas this evening. I'm doing the happy dance over here.

Thank you very much! I am very appreciative of all the guidance and suggestions everyone has provided. I am very happy to be in this group of hams and homebrewers.

Homebrewing a Quantum Computer

Ok, now for something completely different, and something that might help us shake off that Ludite moniker. 

I've seen lots of videos that promise to explain what quantum computing is all about.  Most of them disappoint.  These videos have promise.  

This young lady built a very simple quantum computer at home using lasers and some calcite.  The homebrew angle is very interesting.  At one point in the second video she talks about the benefits of taking theory and using it to actually build something at home.  Indeed.  

I need to spend more time with both of these videos, but like say, they show promise, and they definitely show the spirit of homebrew.  

The first (above) describes the build.  In the second video (below) she uses the build to do a calculation.