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/