Ontario Knack Story

Bill:

I think I’ve finally earned the right to contact you.  I have a really severe case of the knack.  I did not realize it until I discovered amateur radio.  My thinking is that there is no hope for those afflicted with the knack.  I believe that amateur radio helps those afflicted to deal with the condition.  It alleviates the symptoms.   

For years I wandered through the technical wilderness dabbling in physics (I have a M.Sc. in Nuclear Physics), aircraft (I was a tow pilot at a gliding club for several years), high power rockets (www.napas.net), electronics and amateur radio.  The most enjoyable part of radio is not the QSOs it’s the building and the satisfaction of a working device. 

I am relatively new to amateur radio but I’ve always had a passion for all things electronic (and technical).  I am a self-taught electronics geek and have been playing around with digital electronics (PIC microcontroller) for some time know. I starting building altimeters for high power rockets that has the capability of setting off onboard charges  to separate the rocket.  When your rocket reaches 10,000 feet, you cannot open a chute at apogee because it’s going to drift too far and you need to open the rocket at apogee (no chute) and then open the main chute at about 1000 feet to minimize drift. I routinely travel to the US to attend LDRS (large dangerous rocket ships). 

Anyway I had to get my amateur ticket for onboard video camera and trackers (beacons).  Once I got my license and got into radio, it was like a drug!! 

I am now  home brewing everything in my shack.   

When I came across Soldersmoke that was like a super drug.  I downloaded and listened to EVERY episode (seriously!).  I followed you and Mike’s journey and I learned soooo much.  I was devastated when I found out about Mike.   

You inspired me to build my own transmitter.  Earlier this year I built a 20m CW transmitter for my rocket that will eventually send telemetry (in CW from a PIC microcontroller) completely from scratch – no kits – no one’s design. Your early episodes also pushed me to learn LTSpice which I used extensively to model transmitter design of others as well as my own. I’m thinking of calling the transmitter “kaputnik”. 

My design is based on a Chinese AD9850 DDS module which generates a square wave followed by a class E amp (with a tuned circuit).  Puts out 1 watt of power with harmonics down by about 40db.  The reason I used this module with that I can easily change frequency (with mod to tuned circuit)  – after all the DDS module is programmable.  All I need to do now is clean up key clicks because the carrier is turning on too fast.  I playing around with slowly increasing the bias on the mosfet to allow the power output to increase slowly.  Any advice/tips/tricks would be appreciated. 

Next project is a remote antenna switch.   However, you have me close to tackling a SSB transceiver.

Anyway, keep up the great work and I’m looking forward to listening to another 150 episodes!! 

Take care and “stay thirsty” my friend. 

73
Dave Rajnauth, VE3OOI

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

An update from Yi Yao, VA3YAO

We did a short article on Yi Yao a while back, noting that he definitely has The Knack.   His homebrew frequency counter (above) confirms that he does.   In a recent  e-mail from him I also detect an inclination toward poetry.  April is Poetry Month, so I thought I should share the latest from Yi:

Hi Bill,

I haven't gotten around to making my first rig yet. But, after
listening to SolderSmoke since the beginning, it seems like the universal rule
of homebrewing has been to avoid regens!

I've been focusing on mechanical design for the last while. Having
spent 2 years in a heavily electrical engineering oriented
environment, I decided to try something new. Most of the smoke that
 I inhale these days is from cutting oil vaporizing as I turn something
on the lathe. Chips mean bits of metal that are created from cutting
metal. Soldering is done with a torch. The common thread with
electronics is the knackish pursuit of elegant design and beautiful
construction.

I've been thinking about getting myself a copy of SSDRA, but even
looking at online used book stores, this is costing in the
neighbourhood of some of my university textbooks. There's no shortage
of good information and ideas for homebrewing online though. I think
that's what I will use.

Cheers,
Yi


Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

VE7BPO on "Killing Q"

I'm still scratching my head a bit about HOW the resistor prescribed by Edgardo, LU1AR, cured the 250 kHz oscillation problem that was plaguing the JBOT amplifier in my 20 meter DSB rig.   Earlier I'd posted an excerpt from a CQ article in which Doug DeMaw talks about swamping and Q killing.   Last week I got a very thoughtful e-mail from esteemed homebrewer Todd,  VE7BPO.  Here is an excerpt :

Thoughts and Considerations
Let’s discuss squashing low frequency oscillations in a QRP transmitter; say at 200 KHz or so. A low value resistor across the coil (12t -- FT37-43) often works well to stop these.
Oscillations come from the transistor: gain versus frequency isn’t linear, nor is impedance at transistor ports. We’ll often add negative feedback and such to stabilize an amplifier towards unconditional status. In my Tx circuit that oscillated, no feedback was applied. 
 In the case of an inductor wound on a FT37-43 or FT50-43, the Q is already low (say 8- 15 or so). Obviously a resistor in parallel with such a coil is not going to lower Q since Q is already quite low. That R will reduce the inductor impedance and thus may serve to decrease the low frequency gain of the RF amplifier to stop any low frequency oscillations. This might not work so well with a way-high fT transistor where decoupling might be hampered if UHF oscillations are singing. 
Doug DeMaw often referred to the parallel resistor as a Q-killer. If we examine the equations describing parallel, or series resonant circuits -- if the Q of a tank is high enough, we can practically ignore the effect of resistance at resonance. Conversely if we add a resistance and make it high enough, we might even obliterate the resonant frequency or “kill the Q”. Engineers have long placed an R into a parallel-tuned circuit to drop Q and stop oscillations — they refer to it as damping. 1 example might be in old TV sets where a variable resistance was added to peaking coils to prevent a tank from ringing at a frequency determined by the coil L and distributed C. This applies to higher Q inductors and not our FT37-43 inductor. 
Decoupling
Our teacher, Wes, teaches us in EMRFD that coupling often occurs along the DC power supply lines.  Further, he’s taught us to decouple AC by placing high impedance in this path.  Often the impedance is a low-pass filter with series element(s) of a high Z and shunt element(s) with a low Z.  The filter must present a simple short circuit (or perhaps just a resistance) at low frequency so DC flows to the amplifier.    
Final 
Oscillations should likely be identified and treated according their frequency. This topic looks advanced and all RLC networks deserve more attention from us.
Todd, VE7BPO --- Feb 27, 2013  

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Eddy's "Salvage Super"

I had our friend Grayson (in Turkey) in mind when I put Eddy's messages about this "thermitron" receiver on the blog.  

Here's my version of the famed "Mate for the Mighty Midget": http://www.gadgeteer.us/erart.htm 

Hi Bill,

Many thanks for the FB note...

Well, I think my buddy VE3CSK is 99% "hooked" on the notion of making an MFTMM receiver for himself---and that's a good thing. That rascal of a rig is pretty much fool-proof, & the design sure does lend itself to no end of enhancements / improvements / changes / mods! I should know: with my set-up here I added AVC, and extra IF stage, an extra stage of AF, more pre-selection, etc. etc. etc.

As for selectivity, I simply incorporated regeneration in the 2nd IF stage: with judicious tweaking of the BFO, one can achieve a near single-signal selectivity effect that is GLORIOUS on CW. I guess one can make these things as complicated---or as simple!---as we might chose to do, yet further proof of the flexibility of this receiver.

I've taken some jpegs of my set-up here, and am attaching them herewith for your perusal. I like the notion of using these rigs on 80- and 40-meter AM, too---but am presently somewhat "distracted" with the task of re-inking my main tuning dial for my 1929-style superhet.

I think my next step in my MFTMM receiver here will be the addition of an internal 125 VDC power supply---most likely will mount the components inside, on one of the vertical sides (still LOTSA room there!). I have a FB Hammond power transformer that'd be perfect for the job, & I won't have to connect / dis-connect / re-connect its current out board power supply (that I use with other peripherals, too---a REAL pain by times).

~73~ de Eddy VE3CUI - VE3XZ

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Mates for Mighty Midgets

Hi Bill,

Gosh, we haven't exchanged e-mails for---literally---years now...! You may recall me from those heady days of yore when we both worked on / built / modified / boast of our respective MFTMM receivers...

A good friend of mine---Bill, VE3CSK---is in the process of collecting parts for an HB receiver, & I've been trying to sell him on the idea of an MFTMM: I keep telling him it's an excellent "foundation" receiver, & that it'll prove to be much more than a toy, or pleasant diversion, if he leaves enough room on the chassis & the front panel for future mods. I think I may be finally winning him over: he's asked me for the references to the rig, & has placed an order for a National-brand slide rule dial with a fellow Stateside!

Do you still have your receiver, Bill...? If so, do you have any nuggets of info that might be worth sharing re. it, that I could pass onto Bill...?

I've since built yet another superhet here---in keeping with my interest in 1929-ish radios, I built this thing, & have been having a ball ever since: http://www.superhets.info/page9.html

This rascal can REALLY play---but it's a LOT larger than my MFTMM rig!

~73!~ de Eddy VE3CUI - VE3XZ

-------------------------------------
Hello Eddy!  Great to hear from you.  I like you FB page on the Super Hets.  Beautiful. 

Yes, I still have my MMRX.  Haven't used it for a while, but I am thinking of putting it back in operation -- I am now getting active on 75 and 40 AM, and it would be fun to use this RX. 

Here is an idea:   The 455 kc filter crystals are now un-obtanium.  But I'm thinking that we could substitute some 455 kc ceramic filters, which are readily available.

I like the receiver.  A lot.  So far it is my only real tube HB project.  Encourage your friend to give it a go!  

Keep me posted!  73  Bill  

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

VE3ICH's Ugly Weekender

Wow Jeff -- thanks for the kind words in the credits.

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics"http://soldersmoke.com/book.htmOur coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmokeOur Book Store: http://astore.amazon.com/contracross-20

Yi Yao has The Knack!

Hi Bill,

I discovered SolderSmoke a few years ago by listening to another pod
cast. Ever since, I have been hooked on this podcast and listen to it
whenever I have time. I have finally caught up and finished episode
142 today. I love the enthusiasm and spirit of discovery and creation
that goes into the stories in SS.

The first time I heard about amateur radio was in high school. It
seemed to be a overly nerdy thing at the time and I wasn't sure what
it was. However, after I started listening to SS, I discovered that
this is something that I wanted to do. So, on New Years Eve with the
kind help of a local examiner (Ori, VA3XW), I wrote my basic and
advanced exam and passed with honours. In Canada, we only have 3
categories: basic, advanced and morse code. I am very excited about
this and I am glad that SS made me make the jump.

You know, every time the word knack comes up, it is portrayed in a
negative way. Someone is "afflicted" with the knack or shows knackish
"symptoms" as if it was a horrible disease. I would like to change
this perspective.

I hereby declare myself blessed with the knack. Ever since I was a kid,
I disassembled various electronics around the house (to the dismay of
my parents). I knew when I was doing something right when I could put
something back together and it worked, or later, it worked better than
before. Despite my parents' persuasion to pursue other branches of
non-technical studies, I made up my mind to study electrical
engineering (must have been a teenage rebellion thing). Nonetheless
I finished school and found a job doing electronics design which I
love. Some of the people that you meet in this field are just
phenomenal. It has been a good career decision and I think it is truly
amazing. Thus, I see the knack as being a gift which I was fortunate
enough to hold.

I think one of the most important aspect of the knack is the desire to
understand and have self reliance on what we use on a daily basis. I
repair my own bikes and I've never bought a ready made computer.
Having a home machine shop greatly helps in this regard too. My first
oscilloscope I designed and built myself:
http://yyao.ca/projects/oscilloscope/
I have also resolved to build my first rig instead of buying one.
However, work is really busy these days, and it doesn't look like I
will be able to do this soon. One of these days, I will construct my
own rig and wiggle the ether.

I am currently visiting Silicon Valley here in California. There is
much to visit and do here. For example, the De Anza Flea Market
happens every 2nd Saturday (which is my first introduction to a swap
meet):
http://www.electronicsfleamarket.com/

The Computer History Museum is amazing:
http://www.computerhistory.org/

For a limited time, you can see Jim William's work bench at the
museum. If you thought your workbench was messy, you haven't seen
anything:
http://www.eetimes.com/ContentEETimes/Images/EELife/williams%20desk.jpg

Now, imagine having the world's most smartest electronics engineers
having dinner together. That's what the Analog Aficionados Party is about:
http://www.edn.com/blog/Anablog/41523-Analog_Aficionados_party_Feb_18_2012.php

On top of that, there are a lot of trade shows which you can go to
check out the latest and greatest of test equipment. They don't have
the same feel as some of my analog oscilloscopes, but they are shiny.
As you can see, this is a paradise for anyone blessed with the knack.

Anyhow, this email is long enough and I hope your eyes haven't glazed
over yet. My best regards to you, Billy, Maria and your wife.

73,
Yi Yao
VA3YAO
Our book: "SolderSmoke -- Global Adventures in Wireless Electronics"http://soldersmoke.com/book.htmOur coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmokeOur Book Store: http://astore.amazon.com/contracross-20