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Sunday, February 25, 2024

Innovation and a Dual Band Sweep with Version 2 of the 15-10 Transceiver

Here are a couple of videos on Version 2 of my 15-10 SSB transceiver.  In the video above I try to show the advances and innovations that have been made since the start of my BITX construction adventure back in 2013.  

 The video below shows the receiver in action this morning on 15 and 10 meter SSB.  I think it sounds pretty good. 

Click on the image for a better look

Farhan asked what the passband of the 25 MHz crystal filter looked like.  I sent him this.  I think it looks very good, and shows that it is possible to use an IF this high.  This permits us to not only set up the transceiver for dual band coverage (in this case 15 and 10 meters), but it also allows for a lower frequency VFO (in this case around 3.5 MHz) with a resulting increase in VFO stability.  

Saturday, February 24, 2024

More on "Kludge" -- Merriam-Webster's Pronunciation Guide


What say our British cousins?  How do you pronounce the word? 

Kluge as in huge? 

Kludge as in fudge? 

Innovations and Inventions in Garages and Basements

The Hewlett-Packard garage

There is a lot of inspirational stuff in this blog post, especially for those of us who work in home workshops, often in garages or basements. 

Thanks to HackaDay for alerting us to this. 

Thursday, February 22, 2024

Some of my Double Sideband Rigs: Azores, Virginia, Dominican Republic

The above video describe a round of mods to the much modded DSB rig. And my alleged winning of the ARRL Sweepstakes (in a very elite category). 

The video above shows where I took the rig in 2014.  Bahia Rincon, Samana peninsula, Dominican Republic.  You can also see my power supply. 

Here is an article on the first DSB rig that I built, out in the Azores:  


I think the article captures well the trials and tribulations faced by new homebrewers, perhaps with the twist that comes from being out in the middle of the Atlantic ocean.  

Mike WU2D is having similar fun with his homebrew 10 meter DSB transceiver: 

I was struck by how similar Mike's early QSO experiences were with mine.  We both put our DSB transmitters on the air before they made their way into real cabinets or boxes. 

Here's mine from 2001 in the Azores: 

The Mars Helicopter and its CO2 Insulation

This video isn't about homebrew ham gear, but nonetheless I found it very interesting.  Of particular interest is the bit about their need to find a very low-weight insulator to protect the instruments from the cold of the Martian night.  Aerogel would have been too heavy.  So they just filled the instrument chamber with Carbon Dioxide.  That was their insulator. Think about that, especially those of you who still deny CO2's ability to heat up the atmosphere.  

There is a lot of great stuff on Veritasium's YouTube  channel:  

Monday, February 19, 2024

Grayson Evans KJ7UM Video on Homebrewing with Thermatrons

Grayson Evans KJ7UM is the author of Hollow-State Design for the Radio Amateur, a wonderful book about using Thermatrons (aka tubes, or valves) in radio projects. Buy it here:


More info on the book is here: https://kj7um.wordpress.com/2020/12/02/hollow-state-design/ In this video, Grayson talks about construction techniques (including the use of Thermatron Me-Pads), and Manhattan construction for Thermatron projects. FB! Visit Grayson's blog: https://kj7um.wordpress.com/

Jean Shepherd has Trouble with his Heising Modulator (and his date)

This is probably Jean Shepherd's best program about homebrew ham radio.  It is about how we can become obsessed with the problems that arise with equipment that we have built ourselves, and how normal people cannot understand our obsessions.   

I posted about this back in 2008, but I was listening to it again today, and quickly realized that it is worth re-posting.   Realize that Shepherd's Heising modulation problems happened almost 90 years ago.  But the same kind of obsession affect the homebrewers of today.  

Note too how Shepherd talks about "Heising" in Heising modulation.  Heising has an entire circuit named for him, just like Hartley, Colpitts, and Pierce of oscillator fame.  Sometimes, when I tell another ham that my rig is homebrew, I get a kind of snide, snarky, loaded question:  "Well, did you DESIGN it yourself?"  This seems to be a way for appliance operators to deal with the fact that while they never build anything, someone else out there does melt solder.  They seem to think that the fact that you did not design the rig yourself makes your accomplishment less impressive, less threatening.  This week I responded to this question with Shepherd's observation -- I told the enquiring ham that my rig is in fact homebrewed, but that I had not invented the Colpitts oscillator, nor the common emitter amplifier, not the diode ring mixer, nor the low-pass filter.  But yes, the rig is homebrew, as was Shepherd's Heising modulator.    

Guys, stop what you are doing. Put down that soldering iron, or that cold Miller High Life ("the champagne of bottled beer") and click on the link below. You will be transported back to 1965 (and 1934!), and will hear master story-teller Jean Shepherd (K2ORS) describing his teenage case of The Knack. He discusses his efforts to build a Heising modulated transmitter for 160 meters. He had trouble getting it working, and became obsessed with the problem, obsessed to the point that a girl he was dating concluded that there was "something wrong with him" and that his mother "should take him to a doctor."

This one is REALLY good. It takes him a few minutes to get to the radio stuff, but it is worth the wait. More to follow. EXCELSIOR! FLICK LIVES!

Saturday, February 17, 2024

Nate KA1MUQ's Amazing Thermatron Receiver

Wow, some really wonderful work is taking place in Nate KA1MUQ's basement in California. 

-- I really like the pill bottle coil forms.  I wonder if Nate faced suspicion (and possible arrest) in the pharmacy when he asked for the pill bottles.  (I got some suspicious looks when I went I asked for empty pill bottles while building my thermatron Mate for the Mighty Midget receiver back in 1998.) 

-- The variable capacitors are also quite cool, as is the big rotary switch.   Is that for band switching? 

-- Oh  man, all on a plywood board.  Frank Jones would approve!  

-- Indeed Nate, that beautiful receiver NEEDS an analog VFO.  And we need to hear it inhaling phone sigs, not that FT8 stuff. 

-- Please keep us posted on your progress.  And of course, one hand behind your back OM.  Lots of high voltage on those thermatrons.  

Thanks Nate!  

Friday, February 16, 2024

Shuji Nakamora and his (Juliano) Blue Gallium Nitride LED

Lots of great stuff in this video:  

-- They get the charge carrier thing right:  contrary to many presentations, holes don't really move in a semiconductor.  Electrons move to fill holes, making it appear that the holes are moving. 

-- Interesting that Nakamura was so willing to defy company orders for so long. 

-- The description of the discipline that powered his inventiveness is inspiring. 

-- The way he was treated (badly) in Florida because he lacked a PhD is sadly illuminating. 

-- The discussion of corporate infighting is interesting.  

We wrote about Nakamura before:  https://soldersmoke.blogspot.com/2021/02/shuji-nakamura-inventor-of-juliano-blue.html

Thursday, February 15, 2024

More Inspiring Mail! Another "First Ever Receiver was Homebrew"

Frank's Lowfer Beacon Receiver

It was great to hear from someone else who, like Scott KQ4AOP, heard his very first signals on a homebrew receiver.  That is a really wonderful way to start.  Frank's first receiver was built around the NE602 chip.  I had trouble understanding this IC but I finally cracked the code: 


The picture that Frank sent is of a more recent project, this one a Lowfer receiver that picks up signals from beacons. 


Hello Bill, 

I just wanted to message you and tell you I really enjoyed your book Soldersmoke. I've been listening to the podcast as well.  On the latest one you mentioned a fellow who heard his first ham radio signals on a homebrew receiver, and that's how it was for me as well! There were lots of articles about using  the NE602 in the electronics magazines back in the day. I put one of the circuits together and it worked pretty smoothly... I eventually got my ham radio licence (KC8JJL) sometime in the 90's. The first time I met a ham was when I showed up to take the test!  

I don't do much transmitting these days but I still love to listen and tinker.  Here's a picture of a direct conversion LF receiver I put together... It uses an NE602 and is varactor tuned. It only covers from around 300Khz to just over 400khz  but there are still a few beacons I can hear in MI and WI. 

Frank James

Wednesday, February 14, 2024

We Get Mail! Red Poster? Really a Tapestry from Ecuador

Listener Tobias was laid up yesterday, following the extraction of wisdom teeth. (This seems like an appropriate follow-up to our talk in SolderSmoke Podcast #250 of sBITX "wisdom files" to correct FFT "hallucinations.") Tobias does not appear to have been hallucinating, but he was having trouble seeing what he thought to be a "red poster" in my shack.  

In fact, what he was seeing was a red tapestry from Ecuador that was sent to me by Galo Constante HC1GC way back in 1993.  I was in the Dominican Republic, running my first ever real homebrew transmitter.  Here is an article about this project: https://www.gadgeteer.us/TXHB.HTM  I think Galo was also QRP homebrew.  My log shows that I worked  him eight times from the DR. 

Mitad del Mundo =  Middle of the World (a reference to the equator). 

Here is the QSL I got from Galo: 

Here's a 2022 blog post about a resurrection of this old rig: 

Thanks Tobias for spotting the HC1GC tapestry and reminding me of some great QRP contacts. I hope you feel better OM.  73  Bill 

Tuesday, February 13, 2024

Ferdy HB9DSP's 5 band Moxon -- The Moxhorn!

Click on the image for a clearer view

Wow, I couldn't even build a 2 band Moxon, but Ferdy has built a 5 band version.  He told me that he had to tweak the elements a lot to get acceptable SWR's on all the bands.  20 and 17 are especially tough, because they are so close in frequency.  

More info on his great QRZ page: https://www.qrz.com/db/HB9DSP

Thanks Ferdy! 

Monday, February 12, 2024

Dean's Amazing Homebrew sBITX

I was kind of making fun of  it during SolderSmoke podcast #250, but later that same morning I had a chance to watch the KK4DAS homebrew sBITX in action, in person, and I must say, it was very impressive.  This may be the only homebrew sBITX in the world (please correct me if I'm wrong).  

In the picture above you can see the amalgamation of traditional superhet with modern DSP.  Even for an HDR guy like me, the result is really cool.  Once again, I experienced waterfall envy.  And the sBITX receiver sounds great. 

Dean has written up his experiences with this rig in a blog post.  Check it out for more info: 

Thanks Dean! 

Saturday, February 10, 2024

SolderSmoke Podcast #250 Dean KK4DAS joins Pete N6QW and Bill N2CQR

SolderSmoke Podcast # 250 is ready for download: 


VIDEO VERSION: (1707) SolderSmoke Podcast #250 -- With Pete N6QW, Dean KK4DAS, and Bill N2CQR - YouTube

Intro:   Welcome to Dean KK4DAS.  For 2024 Pete and I hope to jazz things up a bit by bringing in fellow homebrewers to talk about their projects.  Dean is our first victim.  Welcome Dean. 

Some good news:  Several new homebrew receivers are inhaling:  Armand WA1UQO in Richmond has an amazing looking regen.  Scott KQ4AOP in Tennessee got his DC RX working.  Mike AG5VG in Texas has been homebrewing BITX 20s and BITX 40s.  All are on the blog.  

Pete's report: 

-- Recent blog entries on filters,  SSB rig architecture, and of course digital VFOs. 

-- Phasing measurements, quadrature, and the Seeed Xiao RP2040

-- Error in QST article on early SSB transceiver.  ANOTHER ERROR!

--LC VFO on blog!  FB Pete!  

Dean's report:  

-- Tales of woe on the homebrew sBITX

-- Help from Farhan.  

-- Ground Bounce.  FFT Hallucinations.   Wisdom files.


-- Whenever you are tempted to buy something from AMAZON, just start at the Amazon symbol on the right side of the page.  We get a cut from Bezos, and it doesn't cost you anything.  

-- You can try to do the same thing with E-bay.  We are finding a lot of great parts there. 

-- If you see a SolderSmoke post on Facebook,  please Like and forward. 

-- Become a patron!  Go to the Patreon page.  We put the money to good SolderSmoke use. 

-- Visit Mostly DIY RF and buy a PSSST kit!  

Bill's bench:  

-- Building yet another BITX dual bander.  15-10 again. Tried to use a 25 MHz filter left over from the earlier project, but I had to build another.  Built a new VFO using the variable cap and anti-backlash gear recommended by Pete.  Was a bit tough to get the receiver sounding good.   Had a diode ring as the second mixer, but went back to a singly balanced mixer. 

-- 10 meter AM -- Thanks to Jerry Coffman K5JC for mod. 

Other topics: 

--Counterfeit chips.  Why? 


Wes W7ZOI 

Jim Cook W8NSA  Transoceanic BFO

Grayson KJ7UM -- Vintage Computer Museum

Chuck Adams --Glad to hear that Chuck is doing well.  

Frank Harris  K0IYE --  NO CHIPS!!!! 

ED DD5LP  Antenna software

Eldon KC5U  10 AM We  made a contact

Joh DL6ID  10 AM   

Phil   W1PJE of MIT   10AM   Where is L5? 

Bob WP4BQV now in UK 

Dino Papas KL0S in Wilmington   Reverse Polarity protection. 

AA7EE Dave Richards  Liked Armand's receiver

Rogier PA1ZZ  

Jonathan-san W0XO  Listened to my ET-2 CW Whoop,whoop

Nick M0NTV  Great videos from Nick the Vic

Will KI4POV  Working on his own SSB rigs.  

John West -- Who is the South American ham who made his capacitors and heat sinks? 

Ed KC8SBV  Working on DC receiver, experimenting with FETs 

Mike WN2A great contributions.  Si5351 sole source danger! 

Nick N3FJZ -- watch out for dead bands when testing receivers! 

Don KM4UDX encouragement from new Prez of VWS

Dave K8WPE Likes QF1 Cap backlash.  Says I'm getting soft! 

Dave WA1LBP My fellow Hambassador, from Okinawa USMC Sergeant with a workshop. 

Wednesday, February 7, 2024

Videos from Mike AG5VG -- His Homebrew BITX Rigs

Here are two great videos from Mike AG5VG showing his two homebrew receivers in action.  (The transmitter portions of Farhan's circuit will come later.) See yesterday's post for more details. 

On the video above (40 meters) 
-- I love that speaker.  
--  The enclosure and the reduction drive for the VFO is really great.  FB OM. 
-- Very cool that Mike captures a 40 meter QSO with "Wild Bill" ZS6CCY in South Africa, someone who we've spoken to many times, often on the long path, sometimes from Mozambique. 
-- I like how Mike demonstrates the effect of removing the antenna.  You can definitely see what we mean when we say you should be able to "hear the band noise."   

Above you see the 20 meter receiver in action.  You can see one of the physical benefits of using a wooden base:  You can easily mount connectors, switches and tuning controls using just pieces of copper-clad board screwed into the wood.   This is what I am doing with my latest BITX 15-10 rig. 

For the tuning of the VFO, it looks to me as if Mike has a large "main tuning" control in the center, with a smaller "fine tuning" or "bandspread" control off to the left.  Does that smaller control work with a varactor diode or with a smaller variable cap?  Also, to the right of the main tuning control we see a 3 pole switch.  Is that switch putting additional L or C into the VFO circuit to move the frequency around?  These techniques would all be quite valid;  Mike demonstrates that there are many ways to skin a cat (or tune a VFO!) 

Mike:  Please send more info. 

Tuesday, February 6, 2024

Pine Boards, Analog VFOs, and Homebrew BITX Transceivers -- AG5VG's Magnificent Creations

Click in image for a better view

This is amazingly cool.  WE ARE NOT ALONE!  There are others out there breaking the tyranny of the Si5351, building BITXs with analog LC VFOs.  And using copper clad boards affixed to pine boards. Plywood cabinetry!  And medicine bottle coil forms.  Really great.  And what a wonderful workshop. Thanks Michael.     

Good Afternoon Bill,

This is Michael Sahn, AG5VG.

I hope your doing well, all is well here in south Texas. I have recently built a bitx20 receiver and bitx20 for 40 meters receiver.

I built it using the analog VFO and both of mine are stable. What an awesome feeling it is to have a stable homebrew VFO. I have attached pictures .

It’s been a fun journey to get to this step. I have just been enjoying the receiver as Farhan instructed us. Then I’m going to go through the transmit side.

Air core coils are great for VFO. On my bitx40 I used a medicine bottle bottom but I put the VFO in a tin can as you will see in the pictures.

The bitx20 is all out, hand capacitance is a slight issue but it’s all learning experience.
Going to be adjusting the pvc coil bandpass filter inductors, I think the value is a bit off so it’s not as loud as it should be, but everything else is set good.

Just wanted to check in and great job on the videos and podcasts. I really enjoy them


Click on image for a better view

Click on image for a better view

Monday, February 5, 2024

"The Soul of a New Machine" -- Re-reading the Classic Book by Tracy Kidder

This book is especially important to the SolderSmoke community because its title has led to one of the most important concepts in our community and our lexicon:  That we put "soul" in our new machines when we build them ourselves, when we make use of parts or circuits given to us by friends, or when we make use of parts (often older parts) in new applications.  All of these things (and more) can be seen as adding "soul" to our new machines.  With this in mind I pulled my copy of Tracy Kidder's book off my shelf and gave it a second read.  Here are my notes: 

--  On reading this book a second time, I found it kind of disappointing.  This time, the protagonist Tom West does not seem like a great person nor a great leader.  He seems to sit in his office, brood a lot, and be quite rude and cold to his subordinate engineers.  Also, the book deals with a lot of the ordinary stupid minutia of organizational life: budgets, inter-office rivalry, office supplies, broken air conditioners. This all seemed interesting when I read this as a youngster.  But having had bosses like West, and having lived through the boring minutia of organizational life, on re-reading the book I didn't find it interesting or uplifting.  

-- The young engineers in the book seem to be easily manipulated by the company:  They are cajoled into "signing up" for a dubious project, and to work long (unpaid) hours on a project that the company could cancel at any moment. They weren't promised stock options or raises;  they were told that their reward might be the opportunity to do it all again. Oh joy.   This may explain why West and Data General decided to hire new engineers straight our of college: only inexperienced youngsters would be foolish enough to do this. At one point someone finds the pay stub of a technician.  The techs got paid overtime (the engineers did not), so the techs were making more money than the engineers (the company hid this fact from the engineers). The young engineer who quit probably made the right move. 

-- The engineers use the word "kludge" a lot.  Kidder picks up this term.  (I'm guessing with the computer-land pronunciation that sounds like stooge.)  They didn't want to build a kludge.  There is one quote from West's office wall that I agree with:  "Not everything worth doing is worth doing well." In other words, don't let the perfect be the enemy of the good.  Sometimes a kludge will do. 

-- Ham radio is mentioned.   One of Wests lead subordinates was a ham as a kid.  Kidder correctly connects this to the man having had a lonely childhood. Heathkit is also mentioned once, sarcastically.  

-- The goal itself seems to be unworthy of all the effort:  They are striving to build a 32 bit computer.  But 32 bit machines were already on the market.  The "New Machine" wasn't really new.  

-- Kidder does an admirable job in describing the innards of the computer, but even as early as the 1978 models,  I see these machines as being beyond human understanding.  The book notes that there is only one engineer on the hardware team who has a grasp of all of the hardware.  The software was probably even more inscrutable. 

-- I found one thing that seemed to be a foreshadowing of the uBITX.  The micro code team on this project maintained a log book of their instructions. They called it the UINSTR.  The Micro Instruction Set.  Kidder or the Microkids should have used a lower-case u.     

-- The troubleshooting stories are interesting.  But imagine the difficulties of putting the de-bugging effort in the hands of new college graduates with very little experience.  I guess you can learn logic design in school, but troubleshooting and de-bugging seem to require real-world experience.  We see this when they find a bug that turns out to be the result of a loose extender card -- a visiting VP jiggled the extender and the bug disappeared.  

-- Kidder provides some insightful comments about engineers. For example: "Engineering is not necessarily a drab, drab world, but you do often sense that engineering teams aspire to a drab uniformity."  I think we often see this in technical writing.  Kidder also talks about the engineer's view of the world:  He sees it as being very "binary," with only right or wrong answers to any technical question.  He says that engineers seem to believe that any disagreement on technical issues can be resolved by simply finding the correct answer.  Once that is found, the previously disagreeing engineers seem to think they should be able to proceed "with no enmity."  Of course, in the real world things are not quite so binary. 

-- This book won the Pulitzer prize, and there is no doubt about Kidder being a truly great writer, but in retrospect I don't think this is his best book.  This may be due to weaknesses and shortcomings of the protagonist. I think that affects the whole book.  In later books Kidder's protagonists are much better people, and the books are much better as a result: for example, Dr. Paul Farmer in Kidder's book  Mountains Beyond Mountains. 

-- Most of us read this book when we were younger.  It is worth looking at again, just to see how much your attitudes change with time. It is important to remember that Tracy Kidder wrote this book when he was young -- I wonder how he would see the Data General project now. 


Here is a book review from the New York Times in 1981: 


Here's one about a fellow who also re-read the book and who provides a lot of good links: 


Sunday, February 4, 2024

Scott KQ4AOP Successfully BUILDS a Receiver (Video) -- This is the Homebrew Spirit at its Maximum

This is just so cool.  Scott KQ4AOP has successfully homebrewed a ham radio receiver.  He used the circuit Dean and I developed (with a lot of input from Farhan and others) for the High School receiver project.  But Scott has had more success than any of our students.  And I think he has had -- in a certain sense -- more success than any of us.  After all, how many of us can say -- as Scott can -- that he used a homebrew receiver that he made to listen -- for the very first time -- to amateur radio signals?  Scott writes:  "Those first sounds were my first time ever hearing any Amateur Radio first hand!" 

In the email below, you can see Scott's deep commitment to homebrew: "I want to build my own gear for 40m. I want to learn morse code. I want my first contact to be on my own gear."  Wow Scott, the building of the receiver is the hard part, and you have already done that.  I think you are well on your way.  

In the video above you can watch Scott tune the entire 40 meter band and a bit beyond. You hear CW at the low end.  Then FT-8.  Then SSB.  Up just above the top of the band I think you can hear our old nemesis Radio Marti.  And this powerful broadcaster is NOT breaking through on the rest of the band.  FB Scott.  Congratulations.  



Thank you for the quick response, direction, and pointers. I won't give up, and I am not in a rush. 

I have wanted my amateur radio license since the early-to-mid-80s. I got my Technician and General in May of 2022 and completed my Extra in May 2023. I always wanted to understand how to design circuits, and I wanted to build them. I share that background to say that I have this impractical goal that I am stubborn enough to stick to (all due respect to you and Pete's advice on the topic of getting on the air). I want to build my own gear for 40m. I want to learn morse code. I want my first contact to be on my own gear. So, your blog and podcast really resonates with me. 

I am only teaching myself at this point. It was the perfect project for my goals. I thought that if all these high school kids in Virginia, Canada, and Germany can do it, it was the sweet spot I was looking for. 

The only transceiver I have was recently gifted to me. It is a Sommerkamp TS-788DX CB radio that allegedly works on 10m in addition to CB. I haven't connected it up because I wanted to stay focused on the HSR. I have a mentor who has gear that I can use to test the oscillator. I am not involved with the nearby ham club, but I know they would help if needed. 

Thanks again and I will keep you posted,

73 Scott KQ4AOP

Bill and Dean - Thank you for sharing and documenting this receiver. I greatly appreciate you publishing the circuit, class notes, and build videos. That got me 75% to completion.
I feel blessed that both of you chipped in and encouraged me through the troubleshooting to finally getting the receiver to start “breathing RF”.
Those first sounds were my first time ever hearing any Amateur Radio first hand!

Saturday, February 3, 2024

Armand's Receiver -- A Beautiful Regen from WA1UQO

Armand writes:
The video above shows a quick pass up 40M. The radio sounds better than the video would have you believe (better than I expected). So now the Select-o-Ject circuit is next (Stay tuned Grayson).
A long list of folks helped with bringing this project as far as it has come. The original description was by Bruce Vaughan, NR5Q SK. Jim Stoneback, K4AXF tweaked it and added the Select-o-Ject circuit.
The power supply picture (below) shows a ganged potentiometer and two empty sockets. These will be for the Select-oJect.
Anyway, it was a fun build and I learned a lot. Now I'm at the point that Farhan advises to make a cup of coffee and just enjoy listening.
73, Armand



Power Supply 

Friday, February 2, 2024

First Light! First Signals received on Version II of Homebrew 15-10 Transceiver

Ianis S51DX in Slovenia was the first call sign heard. Some peaking and tweaking remains to be done, but the receiver is working.

Congratulations to Scott KQ4AOP who got his Direct Conversion receiver working yesterday, And congratulations to Armand WA1UQO who got his regen receiver working. I think all of us are following Farhan's advice and are taking some time to just listen to the receivers we have built ourselves.

Thursday, February 1, 2024

Wilson Cloud Chambers - I Want to Build One

Wow, I've been wanting to build a Wilson Cloud Chamber for a long time, ever since I read about one back in the 1970s in C.L. Stong's famous book "The Amateur Scientist."  Now this fellow Jim Messier comes along with this amazing video that features a cloud chamber that he built for a few bucks at age 13.  I am feeling the pressure.  No pun intended. 

Back in the day, a reasonable excuse for not building this device was that it was hard to find the dry ice you needed for the cooling. No more!  Now, at least in this area,  you can get dry ice at your local supermarket (bring thick gloves or else you can burn your hands on this stuff).  The heat is on.  Well, actually the cold is on.  

I wrote about cloud chambers before on this blog: 

You can get the entire C.L. Stong book for free courtesy of KE5FX here: 

All of this was sparked by a visit to Jim Messier's amazing YouTube channel, "Our Own Devices."  There is a lot of great material there. Check it out and subscribe:  https://www.youtube.com/@CanadianMacGyver 

Thanks Jim! 
Designer: Douglas Bowman | Dimodifikasi oleh Abdul Munir Original Posting Rounders 3 Column