Podcasting since 2005! Listen to Latest SolderSmoke

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

73s
Michael

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: 

https://archive.nytimes.com/www.nytimes.com/books/99/01/03/specials/kidder-soul.html?CachedAug

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

https://auxiliarymemory.com/2017/01/06/rereading-the-soul-of-a-new-machine-by-tracy-kidder/

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.  

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

 Bill,


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

 

Receiver

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! 

Wednesday, January 31, 2024

My Manhattan-style Termination Insensitive Amplifier Production Line

 

You gotta love the name, right?  It sounds like some sort of psychological condition.  Perhaps someone who just doesn't care  if his girlfriend breaks up with him, or is indifferent to getting fired.   

But no, we know that that's not what it means. 

I recently had to make three sets of TIA amps for my new 15-10 rig.  First, I decided not to use the boards provided by Todd of Mostly DIY RF.  You can see one of these boards above the tin shears in the picture above.  Note how compact it is.  Even though you would need two of these (one for receive, one for transmit) to get what you need for a bilateral rig like the BITX,  using these boards (as I did on my 17-12 rig) saves you a lot of space.   But this time I wanted to build a rig that is TOTALLY DIY RF.  So out came the tin shears and the super glue. 

First I decided on the Manhattan pad placement.  I used a pattern that had worked on previous rigs. Pete is right -- I use a lot of TIAs (but no, I have no tattoo of the circuit anywhere on my anatomy!).  I scaled it down a bit, thinking that I could come a bit closer to Todd's compactness.  

Knowing that I would need three sets,  I first made three boards.   Then it was just a matter of soldering in the components:  I did resistors, then capacitors, then, finally, the transistors.   In this way I was able to put together the three dual TIA amps in a couple of morning build sessions.  It was kind of tight and I had to be careful to avoid wiring errors or unintentional shorts.   But it worked. 

I like the TIA circuit.  It lets me select the gain of a stage by simply using two resistor values from W7ZOI and K3NHI's chart.  And with this circuit I know that it will look like 50 ohms both ways.  This is really important on bilateral rigs like this.  

I don't think there is anything wrong with using BITX-like bilateral circuits or TIAs or LC VFOs.  This is all for fun right?  I just like using these circuits.  

My friend Pete is right in pointing out that the bilateral concept did not originate with the BITX -- it has been around for a long time, going back at least as far as the Cosmophone.  But I think Farhan's BITX definitely moved it into the solid-state homebrew mainstream.   Three cheers for Farhan for doing that.  

Tuesday, January 30, 2024

Yet ANOTHER Homebrew 15-10 SSB Transceiver (Video #1)


A homebrew 15-10 SSB Rig for the Dominican Republic:

This is my second build of this rig.

I am using a 10 pole crystal filter that I built for the first build, but did not use. I am also using the tuning capacitor from a Galaxy V's oscillator -- I like the anti-backlash gears and the reduction drive. This rig is built on a pine board covered with adhesive copper tape. It has been built stage-by-stage on copper-clad boards using the Manhattan construction style.

The structure of the rig is basically that of a BITX rig -- the RF and IF amplifiers are Termination Insensitive Amplifiers.

Soon the receiver will be completed. I will then build the stages needed for the transmitter portion of the transceiver.

I will take this rig with me to the Dominican Republic.

Monday, January 29, 2024

The System Source Museum (Computers, Maryland)


Thanks to my friend Bob KD4EBM for alerting me to this.  Bob provides some very useful background: 


(Just north of Timonium, colocated with the future home of the National Electronics Museum)

System Source has a computer museum displaying technology from the inception of computing. Founders Bob Roswell and Maury Weinstein opened ComputerLand, a predecessor to System Source, in 1981. Rapid advances in technology in the early 1980’s made some ComputerLand inventory obsolete before it could be sold. Bob and Maury’s old ComputerLand store on Redwood Street had a bank vault in the basement, so they filled it with vintage tech.

Wow, that bank vault in the basement is really intriguing.  We need to find more of those.  

The Usagi guy's 6AU6A T-shirt is pretty cool.  I also liked his reference to Tracy Kidder's book "The Soul of A New Machine."  I happen to be re-reading that book now.  I'm struck by the complexity of even the computers of the late 1970s.  At one point Kidder notes that there is only one guy on the hardware team who has a complete grasp of how the hardware in the new machine actually works.  The software was probably even more inscrutable.  And of course, things have gotten a LOT more complex.  This is the big reason that I have decided to stick with simple, analog, discrete component, HDR rigs that I can understand.  To each his own.  One look at the wiring on some of those old computers tells me that this is not for me.  

Thursday, January 25, 2024

RIP Arno Penzias -- Co-discoverer of the Big Bang Cosmic Background Radiaton

 

Penzias on the right

Here it the Penzias Obituary:

I think this is one of the best troubleshooting events in radio history:  they thought at one point that what they were hearing was the result of pigeon poop in the antenna.  Turns out they were hearing radiation from the birth of the universe. 

And here is a wonderful 2014 6 minute podcast with Penzias and his co-discoverer Robert Wilson:
 

Tuesday, January 23, 2024

IMSAI Guy Looks at Counterfeit Chips


Like some of the commenters, I had been scratching my head wondering why someone would go to all the trouble of counterfeiting electronic parts.  It just didn't seem to make economic sense.  Perhaps they were just marketing factory rejects?   But no,  IMSAI Guy shows in the video above that it is a lot more insidious.  It turns out that this kind of crime DOES make economic sense (see comments).  So be careful out there. 

Here is another one IMSAI Guy did yesterday, looking at other faked chips: 


Thank you IMSAI Guy
Designer: Douglas Bowman | Dimodifikasi oleh Abdul Munir Original Posting Rounders 3 Column