SolderSmoke Podcast #256: HNY SKN, LA Fires, Barkhausen! Southern Cross, Homebrew vs. Kits, AN762 Kit, Woe, Beacon, ARRL Kids, SDR Build, DC RX videos, Pete Hacked! Power alternatives, KWM4, Mailbag

A Tale of Woe! 

SolderSmoke Podcast #256 is available: 

Audio:  https://soldersmoke.com/soldersmoke256.mp3

Video:  https://www.youtube.com/watch?v=NYuEhljOtAQ

Travelouge:  From the DR.  

Happy New Year! 

Fires in LA.  

Dean:  Breaking the Barkhausen criteria.  

Seeing the Southern Cross for the first time in 30 years. 

For all three of us:  The SolderSmoke Homebrew Challenge.  And assembling a kit. https://soldersmoke.blogspot.com/2025/01/some-history-of-homebrew-ham-radio-from.html

https://soldersmoke.blogspot.com/2025/01/the-magic-that-only-comes-from-radio.html

https://soldersmoke.blogspot.com/2025/01/steve-g0fuw-talks-homebrew-and-kits.html

________________________________

Bill's (Southern) Bench: 

-- SKN with QCX given to me by Bob.  Thanks Bob! 

-- Finishing up the AN762 .1kW amplifier.  Socketry and relays.  Working well.  

-- A tale of woe:  Some difficult troubleshooting on the 15-10 rig. Intermittent oscillation.   Naturally I blamed the TJ DC RX AF amp.  Spent a lot of time working on that amplifier.  But problem always returned.  Started looking at output from carrier osc/BFO.  Waveform weird. Then weirdness disappeared and so did the whooping.  So I rebuilt the entire carrier osc/BFO/ mixer board.  Went back to singly balanced 2 diode mixer.  Used LTSpice for the oscillator amp.. No more whooping.  Turning the diodes on and off  but not quite 7 dbm...  Should I be concerned? 

-- A 10 meter beacon!  28.233   Please listen. Send e-mail reports.   Thanks to WN2A.   

-- Antenna thoughts.  Getting a tripod.  

The HI7/N2CQR 10 meter Beacon

_______________________________

SHAMELESS COMMERCE!   Mostly DIY RF!  Lots of useful kits and boards there.  I have used their TIA boards.  Todd K7TFC is one of us.  FB store. 

Become a SolderSmoke patron.  We need the help.  Homebrew is under seige!  We are one of the few sites, blogs, podcasts that are promoting it!  Help us!  

Buy stuff from Amazon and E-bay using the links on our sites. 

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

Dean's Bench: 

-- ARRL kids day -- Exhausting.

-- VWS Makers SDR receiver build.  

-- High School DC RX Build news. How to watch the videos.  

_______________________________

Pete's Bench:  

-- Hacked! 

-- Power Alternatives. 

-- Thermatron Finals

-- KWM-4. 

__________________________

Mailbag

Dave Newkirk W9BRD (son of Rod).  Great comments on homebrew radio. And a great picture. 

Derek N9TD built the DC Receiver.  FB Derek! 

Peter VK2EMU at 39C in Australia.  HOT! 

Drew N7DA -- Some great comments on kits vs. homebrew. 

Tommy SA2CLC has a nice video about fixing the cavity resonator in his HP8640.  Respect! 

Ben KC9DLM sent good presentation from India: https://github.com/kholia/talks/blob/master/Dhiru_My_RF_Homebrew_Adventures.pdf

Scott KQ4AOP and Derek N9TD offering to 3D Print PTO coil forms.  FB!  

Donnie WA9TGT on the beautiful signals from DC receivers. 

Chuck KE5HPY's FB Altoids DC receiver. 

Todd VE7BPO:  POPCORN ELECTRONICS IS BACK!  Thanks Todd.  And thanks Vasily! 

Jim KA4THC has his uBITX on the air and is making contacts!  

Farhan VU2ESE fond memories of homebrew dinner with Wes and other HB Heroes (on the blog). 

Charlie ZL2CTM -- About his new Pelican Case SSB rig. 

Walter KA4KXX.  All new hams should build a transmitter. 

Buzz W3EMD  A nice QSO on 10 and then a shout out to the Old Military Radio Net

Stations that heard my beacon and reported to RBN

Some History of Homebrew Ham Radio -- From Wikipedia and from K0IYE

Frank Harris K0IYE's Homebrew Station

From Wikipedia:  https://en.wikipedia.org/wiki/Amateur_radio_homebrew 

In the early years of amateur radio, long before factory-built gear was easily available, hams built their own transmitting and receiving equipment, known as homebrewing.^[2] In the 1930s, 40s, and 50s, hams handcrafted reasonable-quality vacuum tube-based transmitters and receivers which were often housed in their basements, and it was common for a well-built "homebrew rig" to cover all the high frequency bands (1.8 to 30 MHz). After WWII ended, surplus material (transmitters/receivers, etc.), was readily available, providing previously unavailable material at costs low enough for amateur experimental use.^[3]

Homebrewing was often encouraged by amateur radio publications. In 1950, CQ Amateur Radio Magazine announced a ‘‘$1000 Cash Prize ‘Home Brew’ Contest’’ and called independently-built equipment ‘‘the type of gear which has helped to make amateur radio our greatest reservoir of technical proficiency.’’ The magazine tried to steer hams back into building by sponsoring such competitions and by publishing more construction plans, saying that homebrewing imparted a powerful technical mastery to hams. In 1958, a CQ editorial opined that if ham radio lost status as a technical activity, it might also lose the privilege of operating on the public airwaves, saying, ‘‘As our ranks of home constructors thin we also fall to a lower technical level as a group’’.^[4]

In the 1950s and 60s, some hams turned to constructing their stations from kits sold by Heathkit, Eico, EF Johnson, Allied Radio's Knight-Kit, World Radio Laboratories and other suppliers.^[5]

From "From Crystal Sets to Sideband" by Frank Harris K0IYE https://www.qsl.net/k0iye/

Dear Radio Amateur,

 I began writing this book when I realized that my homebuilt station seemed to be almost unique on the air. For me, the education and fun of building radios is one of the best parts of ham radio. It appeared to me that homebrewing was rapidly disappearing, so I wrote articles about it for my local radio club newsletter. My ham friends liked the articles, but they rarely built anything. I realized that most modern hams lack the basic skills and knowledge to build radios usable on the air today. My articles were too brief to help them, but perhaps a detailed guide might help revive homebuilding. I have tried to write the book that I wish had been available when I was a novice operator back in 1957. I knew that rejuvenating homebuilding was probably unrealistic, but I enjoy writing. This project has been satisfying and extremely educational for me. I hope you'll find the book useful...

...My personal definition of “homebuilding” is that I build my own equipment starting from simple components that (I hope) I understand. I try not to buy equipment or subassemblies specifically designed for amateur radio. I am proud to be the bane of most of the advertisers in ham radio magazines. I still buy individual electrical components, of course. I just pretend that the electronics industry never got around to inventing radio communications. 

An irony of our hobby is that, when the few remaining homebrewers retire from their day jobs, they often build and sell ham radio equipment. These industrious guys manufacture and sell every imaginable ham gizmo. I doubt any of them have noticed that, by making everything readily available, they have discouraged homebuilding.

K0IYE's Thoughts on Homebrewing and Workshops

Click on the image for a clearer look

I like Frank Harris K0IYE's book so much that I don't mind posting about it frequently.   "From Crystal Sets to Sideband" is must-read material for all homebrewers.  

The picture above is especially significant.  I first came across it in the old pulp-style magazine called World Radio.  The picture, like Frank's book, is truly inspiring.  

This week I stumbled across a relatively new chapter in Frank's book.  Chapter 3A deals with his approach to homebrewing (Luddite, analog, HDR) and his advice on how to set up a home ham-radio workshop.  There is a lot of wisdom in this chapter.  

The opening paragraph of Chapter 3A really grabbed me.  Check it out here.  Click on the text below for a better view: 

Click on the image above for an easier read

Frank's advice on what to do when you get stuck on a problem is right on the mark, and a bit counterintuitive, but very true: Do something else for a while. 

Click  here for all of Chapter 3A:

 https://www.qsl.net/k0iye/CHAP3A.html 

Chapter 3B also looks great. 

And click here for the entire book (including a Spanish translation!) 

https://www.qsl.net/k0iye/

Thank you Frank for sharing with us all of this wisdom.  73 OM   

Building Farhan's PTO -- But Is This Really a PTO?

Farhan has a PTO in his Daylight Again transceiver.  This caught the attention of homebrewers around the world.  Walter down in Orlando built one.  Dean KK4DAS and I have built versions also. Dean has a 3D printer and made the coil support used in my version (above).  Thanks Dean! 

I had a little trouble at first because one of the capacitors I had in there was not NP0, so the device drifted a lot.  But once I straightened that out (I put in a Silver Mica cap in its place) the oscillator became very stable. Mine moves about 25 kHz with each turn of the bronze screw -- this is nicely linear tuning.  But I think I will have to use a San Jian counter to keep track of the frequency. The long plastic tube on mine is there to eliminate had capacitance effects. 

One of the guys in the Vienna Wireless Society questioned whether we should really call this a PTO.  After all, bronze has a permeability equal to that of free space. So we are not really changing the permeability.  Frank Harris points out that the bronze screw really acts as a shorted secondary.  What do you guys think?   Is this a PTO, or do we need another acronym to describe it? 

This has been a really fun project.  I never built an oscillator like this before.  I will probably follow up by building the rest of the Daylight Again rig. 

BTW  WA6OTP has a nice PTO design: http://www.wa6otp.com/pto.htm

Thanks again to Dean, and to Farhan.  

An Analog LC VFO for my 17/12 Meter SSB Transceiver (VIDEO #1)

Here's my initial work on a VFO for my 17 meter -- 12 Meter Single Conversion Dual Band SSB Transceiver. The IF (crystal filter) will be at 21.4772 MHz. On 12 meters the VFO will run from 3.5128 to 3.4528 MHz. On 17 the VFO will run from 3.3092 to 3.3672 MHz.

The transistor I am using is an SK3050 Dual Gate MOSFET. I bought a bunch of these years ago in a panic when I heard that 40673's were getting scarce.

I forgot to mention another important reference: Joe Carr's Popular Electronics VFO articles:

https://soldersmoke.blogspot.com/2017/04/vfo-tribal-design-wisdom-from-joseph.html

Thanks again to Dale K9NN for the bags of NP0 capacitors. And to Pete N6QW for the suggestion on the HT-37 main tuning cap.   Thanks to Mike WU2D for the great VFO videos, and to Frank Harris for his wonderful book on homebrewing.  And we can't forget the great reference books that guide so many of our projects: Solid State Design for the Radio Amateur and Experimental Methods in RF Design -- thanks to Wes Hayward W7ZOI and all of his co-authors.  

"From Crystal Sets to Sideband" -- A Great Book about Homebrew Radio by Frank Harris K0IYE (FREE!)

I first came across the above picture of K0IYE's inspirational, completely homebrew station many years ago in the pages of "World Radio" magazine. I have already linked to Frank's book many times over the years, but it is so good that I regularly feel compelled to write about it again. Frank updates the book. Just check out the introduction to his website. Frank even has a Spanish language version of his book. All for free. Thank you Frank.

The introduction to Frank's web site:

Over the last century amateur radio has evolved into numerous different

hobbies. Some hams enjoy weekend contests in which they try to

contact as many stations as possible. Others talk to as many of the

world's 341 call areas as possible and collect QSL cards to prove it. Other

hams just like to ragchew with friends. Still others communicate over

long distances at UHF frequencies using satellites, meteorites, aurora and

other substitutes for a sunspot-charged ionosphere. Some hams provide

communications for their communities during emergencies.

Many of us have returned to the early days of radio by building our own

equipment from scratch. Most home builders start by building QRP (low

power) transmitters. If this doesn't satisfy your urge to build something,

you can move on to build the entire station. That is what this website is about.

https://www.qsl.net/k0iye/

More Homebrew Wisdom from Frank Harris, K0IYE

In Chapter 13A, Frank Harris writes: 

The Vanishing Art 

The 1986 ARRL Amateur Radio Handbook reported that hardly anyone was building homebrew ham receivers....  Out of hundreds of contacts, so far I’ve worked four guys, George, K7DU, Mike, NØMF, Biz, WDØHCO and Jack, W7QQQ who were using homebrew receivers for the QSO. Three of these receivers were made from vacuum tubes. George's receiver is a beautifully crafted instrument that looks like a commercial design from 50 years ago. All of these receivers had no trouble hearing me on 40 meter CW. I talked to one other fellow, Gil, N1FED who told me he had just finished a vacuum tube receiver. Unfortunately, it was performing so poorly he was still using his modern transceiver on the air. Gil told me he didn’t like transistors. I guess he found printed circuit boards and those pesky oscillations too much trouble. In spite of this pessimism, you CAN build transistorized receivers that work reasonably well. I built mine because I was intrigued by mysterious circuits like “balanced mixers,” “product detectors,” “cascode amplifiers” and “crystal ladder filters.” Before this project, I could recite the purposes of these circuits, but I had no “feel” for how they worked and why receivers are designed the way they are. What better way to learn than to build one? 

Aside from the need to shield circuit blocks from one another, a homebrew receiver with a single big board full of discrete components has another problem. If you build the whole thing at once without buying a kit and pre-cut board, I guarantee it won’t work. To make homebrew stuff that works, you have to develop your own technology based on parts you can get and circuits you understand. Learning to think this way was difficult for me. Rather than “building a receiver,” I had to lower my sights and build one circuit at a time, e.g., “an oscillator,” “a mixer,” “an audio amplifier,” etc. Then I put the blocks together to complete my project. Some of these circuit blocks didn’t work the first time so I had to build a new block. There were various reasons the modules didn’t work. Usually, I wasn’t able to buy the exact parts used in the circuits I was copying. Or my craftsmanship or shielding wasn’t adequate. Sometimes I never did learn why one version of a circuit block was superior to another. By building my receiver using separate little shielded modules for each circuit block, I could replace a circuit block whenever I managed to build an improved version. Otherwise, I would have ruined the entire big board.

On rare occasions my circuits didn’t work because there were errors in circuit diagrams in QST magazine or in the handbooks. I found some serious errors in my 1979 ARRL Handbook and a minor one in my 1998 edition. Perfect editing is not possible, so we shouldn’t expect it.

GET THE WHOLE BOOK HERE (FREE!) 
http://www.qsl.net/k0iye/