Tuesday, March 10, 2015

Shep on Parasitics and Troubleshooting: "That way madness lies"

You guys really have to listen to this. This is culturally important. And it is a great follow-up to SolderSmoke 173.

In this 1965 radio broadcast, Jean Shepherd describes his teenage struggles with parasitics and other technical problems in his homebrew 160 meter transmitter.

He describes the sound of parasitics on a signal, saying that they sound as if the signal is being attacked by "debauched erotic locusts."

He really nails it in describing the scornful, dismissive tone that many hams use in telling their fellow radio amateur that there are problems with his signal. ( I have recently been on the receiving end of this kind of treatment.)

He observes that no one is more worried, "than a man who has built something and can't get it to work." Indeed.

During a date with a girl from his high school, he is so obviously pre-occupied with his transmitter trouble that she tells him that something is wrong with him and that his mother "should take him to a doctor."

And he describes the joy that comes when you figure out the problem and get the thing to work.

The REALLY good stuff begins at about the 25 minute point.

http://ia310115.us.archive.org/2/items/JeanShepherd1965Pt1/1965_01_29_Ham_Radio.mp3

Shep was quoting from King Lear: "O, that way madness lies; let me shun that; No more of that." In other words: "BASTA!" That is what I have said about my 40 meter troubles. My BITX 20/40 is now a BITX 20.

EXCELSIOR!

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

Monday, March 9, 2015

The Original BITX 20 -- Designed at 35,000 Feet in 6 hours, Built in India in 3 Days

I came across what appears to be an early version of Farhan's description of the design and initial construction of the BITX 20 (see below); this version has some interesting information on the origins of this important rig. The picture below shows the designer himself working on that first BITX20. It is from a CNN video. I know Farhan is sick of seeing this old video, so I present here only the shot of the designer's hands at work on the original transceiver.

Some thoughts from the designer, Ashhar Farhan, VU2ESE:

    This transceiver was designed during a six hour flight from Europe with paper, pencil and the basic calculator built into my cell phone. It was soldered in three sittings over three days. Very little went wrong during the construction. It was one of those easy designs. The only mistake that I made during construction was that I soldered one of transistors in reverse. The design worked as ‘advertised’. I guess that extensively using feed back amplifiers provides designers with greater repeatability. Also, I realized, a little late in life though, that detailed forethought and ‘mental’ home-brewing is important for a clean design.
    The linear chain was initially unstable. It tended to oscillate in the 14MHz band as well as around 500 KHz. I traced the 14MHz oscillations to a choke that I was using at the output of the balanced modulator. It has been removed. The 500 KHz oscillations were because of excessive gain in the driver and pre-driver stages. From 5 ohms, the emitter degeneration has been increased to 10 ohms and better bypassing on the power rail has eliminated the oscillations.The receiver is as hot as I need it to be on 20 meters. Signals from USA, Europe, South Africa and of course India were heard with clarity reminiscent of a clean Direct-conversion receiver on the first evening. The transmitter is powerful enough for local rag chew and it is a modest challenge for DX. VU2PEP has an excellent two element beam at 20 meters at about 40 feet height. DX is easy for OM Paddy who uses the rig regularly. We netted LA2FKA within the first 20 minutes of firing up the rig.
    No, I don't offer PCBs. I don't repair rigs. I don't offer kits. I might do a PCB for this rig (I hate PCBs, they hamper experimentation).
    This transceiver is dedicated to the memory of OM Juggie, SK (VU2JH) who was a great organizer of India hams, he wrote technical articles in Electronics For You magazine about amateur radio, spurring many to take on ham radio as a hobby. He organized the Millennium Ham Meet in the year 2000. He was always searching for a good and simple homebrew SSB transceiver. He died young. He gave me my first morse key.

Jagdish, VU2JH

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

Saturday, March 7, 2015

SolderSmoke Podcast 173: Pete's LBS Triumph and Bill's Tale of QRO Woe

SolderSmoke Podcast #173 is available:

http://soldersmoke.com/soldersmoke173.mp3

7 March 2015

Bench Report:   Pete's Progress on the Let's Build Something Rig:
http://www.jessystems.com/LBS_Detail.html
Ben's cool case for his LBS rig
Bill's Tale of Woe: QRO troubles with the BITX 40
    -- QRO amplifier taking off on 40 (but not 17)
    -- Criticism and public humiliation on 40
    -- Troubleshooting
    -- Suggestions from Allison
    -- A sad realization about my VFO frequency selection
    -- Exorcism needed
    -- Pete suggests a digital solution
    -- Wow, my 'scope has an FFT! Almost a spectrum analyzer!
    -- Some thoughts on trouble shooting
    -- On the meaning of "BASTA!"
The Spring 2015 Issue of Hot Iron http://www.walfords.net
More on Pete's KX3
Encouraging other hams to build

Wednesday, March 4, 2015

Video of The Moment Colin Made his First Homebrew Contact With Australia

Our British cousins are not a wildly emotional people. The word "phlegmatic" is sometimes used when describing them. Stiff upper lip and all that. But as you can see at the 51 second mark in this short video, contacting Australia whilst using a new scratch-built homebrew BITX20 on battery power from a windy English hilltop WILL get those English fists pumping and those thumbs up. The wind drowns out Colin's voice, but his gestures say it all. Well done Colin! Brilliant!

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

Tuesday, March 3, 2015

Colin's BITX DX From the Field

That has to be one of the best-looking scratch-built homebrew BITX20s. Pete and I agreed that it looks almost too good to take out into the field. But that is where Colin took it. His BITX was designed for Summits on the Air, and the radio gods rewarded him for his efforts with VK DX. Well done Colin!

Hi Bill and Pete.

Well it just worked out that weather was going to be bearable this morning but getting worse through the weekend. I'm really want to ramp up my SOTA score so I'm trying to get out as much as I can. I switched my plans to an early morning activation on one of the local hills. The hill, called Sharp Haw, is a little lump on the edge of the Yorkshire Dales, it's not very high at all, but it is worth 1pt for SOTA.

The early morning time window brought the possibility of VK QSOs via long path on 20m. I looked at the VOACAP prediction for propagation and it suggested a peak at 0800utc.

I was actually late getting up, my alarm clock batteries have decided they've had enough. Despite the late start, I still managed to get on the air by 0725, hearing a strong Australian accent on the power up frequency of the BITX, 14.200, was a good sign.

At 0737, I was called by VK1DI. I had to turn the AF gain up, but sure enough, the signal was workable and we exchanged reports, 55 for him, 33 for me. Within the space of less than 20 minutes, I had 4 VKs logged, the strongest being VK3DET, giving me a 56. The other two stations were VK3CAT and VK2IO. I also worked an Asiatic Russian station amongst others.

I'm over the moon, I might even apply for my SSB thousand miles per watt wallpaper!

I still find it magical that 25 volts into a bit of 7/0.2 wire can transport your voice across 15,000 miles! Amazing!

73, Colin, M1BUU

Monday, March 2, 2015

Patrick, F6AWY, The SSB Carpenter (Homebrew Hero)

There he is: Patrick, F6AWY, the builder of the beautiful wooden-case SSB transceiver featured here two days ago. Born in 1945, Patrick has been melting solder since age 15. This picture made me think that there must be some connection between string instruments and homebrew genius: Farhan plays guitar. So does Pete Juliano. I think it was Rick Campbell who was strumming the banjo at FDIM... More about Patrick here: http://www.araccma.com/f6awy-p821004

Here is another of Patrick's projects. He completely rebuilt an old Geloso AM transmitter. Note the markings on the front panel. Signed with a dash of F6AWY panache!
More about this project here:
http://www.araccma.com/emetteur-am-pas-a-pas-avec-f6awy-p820986

Translation tip: Open these pages in Google Chrome. Then, simply RIGHT CLICK on the page and select TRANSLATE TO ENGLISH.

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

Sunday, March 1, 2015

Homebrew Heroes at Rickreal Hamfest: W7ZOI and WA7MLH

Bob N7SUR was getting discouraged. The hams at the Rickreal Hamfest didn't seem really interested in his display about homebrewing. Then THE RADIO GODS INTERVENED! (thunder). Two TITANS of homebrew appeared at Bob's table. Keep up the good work Bob, Thanks for the e-mail and the great picture of you with Wes and Jeff.

To N2CQR, N6QW

Feb 15 2015

The Salem, Oregon, Repeater Association puts on two hamfests each year
at Rickreal. This event was mentioned in SolderSmoke #78. During the
last two events I’ve taken a “science project” display and circuit
boards to encourage more hams to experiment. The boards encourage
experimenters to use software packages to design and build their own
receiver modules. It is uncommon to see this type of material at the
event.

Audience interest has been underwhelming. Perhaps a dozen participants
have shown interest in my displays. In fact, I almost left the displays
home last Saturday.

In the course of the morning, two guys approached. The older guy had a look of
familiarity. He looked like a guy in the SolderSmoke blog. Bill,
N2CQR, was pictured sitting with him in California over coffee.

I blurted out, “are you ZOI?” He replied “yes” and I told Wes Hayward,
W7ZOI, it was nice to meet him. (That was a bit of understatement).
With Wes was Jeff Damm, WA7MLH, who built many of the circuits included
in the book “Solid State Design.” I suggested to Jeff he no longer
looked like a hippie, which is the style conveyed by his webpage. Jeff
said he had recently cut his hair.

We spent more than an hour sharing ideas and discussing various topics.
My focus was on encouraging experimentation. Kit building may be a nice
first step. I want to see builders pursuing more advanced
investigations. Wes noted the software and simulation tools available
for free it’s never been a better time to try out ideas. Wes commented
on the contribution of amateurs and how we often have fewer restrictions
to pursuing our interests. He emphasized measurement tools. I should
look more at noise figure in my receiver experiments. He was very
supportive, which contrasts with my recent experiences on various
internet groups.

Wes and Jeff were looking for Rick Campbell, KK7B, and Bob Larkin,
W7PUA. Imagine, the three authors of Experimental Methods in RF Design
(EMRFD) frequenting a little hamfest in rural Oregon. Yet, few people
knew they were there.

The experience reinforced my interest in continued experimentation.
I’ll take my updated displays back next time. Perhaps our efforts reach
a larger audience than we first realize.

Bob-N7SUR

Saturday, February 28, 2015

F6AWY's Beautiful, Colorful, Wooden Box Transceiver

I was beginning to fear that I might be the only radio amateur in the world operating a wooden-box SSB transceiver. But no! Patrick F6AWY built this MAGNIFICENT rig. Wow, I really like this one. Note the Heathkit S-meter and main tuning knob (I suspect an HW-?? carcass lies somewhere nearby). Note the colorful analog dial and speaker cover, and the classy lime-colored Dymo tape knob labels. This is really an amazing and inspirational piece of work.

The construction details are all here:
http://www.araccma.com/le-tranceiver-en-bois-de-f6awy-p820968
Yes, it is in French, but even if you can't get Google or Google Chrome to translate it (and that should be possible) you can see what he did through the great pictures and schematic diagrams.

Congratulations Patrick!

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

Thursday, February 26, 2015

Video on W4OP's Progressive Receiver (Solid State Drake 2-B)

This is so great. I saw pictures of Dale's receiver a few years ago, but somehow missed the video. I am the proud owner of a W4OP-built Barebones Superhet. And, of course, of a Drake 2B (mine has tubes!)

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

A Really Cool Idea: Use your BFO as your Arduino DDS Clock


(21)  If you add a microprocessor chip to augment some of the BITX 

functions, it might be advisable to use the 10 MHZ BFO signal to clock 

your uP.  This could help avoid unwanted 'birdies' from the uP oscillator 

getting into your BITX circuitry.
From a nice list of BITX mods: 

http://kambing.ui.ac.id/onnopurbo/orari-diklat/teknik/homebrew/bitx20/modifications/LIST%20(9-24-04).txt

N6ORS's Long-Delayed SSB Rig

We've heard of a few of these "long-delayed" projects. My own 38 year pause in the Herring Aid Five receiver project comes to mind. I like Keith's idea of a "homebrewers home frequency" but I strongly suspect it would be a very lonely place! Thanks for sending us the pictures of your rig Keith.

Bill:

This project started out about 20 years ago as
a 2 meter FM handheld, then sat in boxes for decades.
Thanks to you and Pete and your podcasts keeping
me company, it morphed into a homebrew 2 meter SSB
rig. It saw 'firstlight' last weekend. Of course
I had to operate it without the covers but I made
a short QSO, about 1 mile across town with the wife (kg6oeo).
Homebrewers should pick a "Homebrew home frequency" on
various bands to facilitate homebrew to homebrew contacts.

73,

Keith N6ORS

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

Wednesday, February 25, 2015

N0YUD's Mighty Mite (complete with harmonics)

Bill N0YUD built this really nice Michigan Mighty Mite. I like the wood base (with little feet!). And the classic black 35 mm film container. And the Vero board. Fancy connectors too! Nicely done Bill.

Bill has also wisely left space for a low pass filter. As you can see in his 'scope picture below, the MMM produces a lot of harmonics. With a low pass filter, that mess will turn into a beautiful sine wave. We'll be talking about harmonics and low pass filters in the next podcast.

Feb 20 at 3:31 PM

Hi Bill and Pete,

I just completed my Michigan Mighty Mite and am proud to announce it seems to be generating about 1 watt of what appears to be extremely harmonically challenged RF. I was worried about the ugly signal on my scope until I saw another screen shot on the blog page that looked almost exactly the same as mine.

What a fun project and lots to learn with just 7, or in my case 8, parts (I had to stack a couple of 56ohm resistors). I utilized those small pc board sockets for the coil and crystal so I can easily change bands and also left room for a low pass filter....

I am still struggling with the tank coil theory and impedance... Impedance matching is a very murky area for me!

I am looking forward to building the low pass filter. By the way, I checked for third and fifth harmonics and could not hear anything on my receiver. There's another question, why does this circuit generate odd harmonics? Fun stuff, this learning game!

I love the Podcast! Thank you for your efforts and keep them coming.

'73

Bill McMillan

N0YUD

Tuesday, February 24, 2015

TR on Homebrewing

"It is not the critic who counts; not the ham who points out how the homebrewer stumbles, or where the builder of rigs could have built them better. The credit belongs to the ham who is actually at the workbench, whose hands are scarred by solder and metal and glue; who strives valiantly; who errs, whose amp oscillates again and again, because there is no effort without error and shortcoming; but who does actually strive to build his rigs; who knows great enthusiasms, the great devotions; who spends himself in a worthy cause; who at the best knows in the end the triumph of high achievement, and who at the worst, if he fails, at least fails while daring greatly, so that his place shall never be with those cold and timid operators who neither know victory nor defeat.”

Monday, February 23, 2015

Parasitic Anguish on 40 then... Homebrew Transceiver Heard by Homebrew Receiver (with a PTO!)

Oh man, I was struggling yesterday. I guess I had been lulled into a false sense of security by the phenomenal ease with which I had put my BITX 17 on the air, then added a 120 watt amplifier, all without any sign of the dreaded feedback and parasitic oscillations that had plagued almost all of my previous projects. So when I decided to add the low pass filter and the switching/relay arrangements needed to use the amplifier with my BITX 20/40 rig, I kind of expected a similar trouble-free experience.

WRONG! And you know what? I think guys on 40 and 20 are a bit less forgiving and collegial than the folks on 17. As I struggled to exorcise the transceiver, I'd make some changes then hopefully go out onto the airwaves and call CQ, looking for a signal report. Well, I got them. Many were not accompanied by call signs. I'd be in contact with someone who was trying to help, and -- as we were trying to figure out what it might be -- we'd be bombarded with harsh, sometimes angry, anonymous commentary: "YOU'RE 20 kcs WIDE!" "Are you on AM?" "You have a CARRIER!" One fellow scornfully told me "That little QRP rig of yours is not ready for prime time." Ouch. (I didn't realize we were on prime time. Isn't this AMATEUR radio?)

Others would answer my CQ by announcing that I was "on the wrong frequency." Others would respond (off frequency) and tell me I was distorted -- I'd ask them to tune me in, then they would say, "Oh yea, you are OK -- you were just on the wrong frequency." Some of these guys seemed to be under the impression that there are "channels" on 40 meters. It was a real disheartening mess.

Then came the saving grace. I got the e-mails that appear below. WOW! My faith in ham radio was renewed! In the 18 months that I've been running the BITX rigs, I've never once worked another station using a homebrew rig. But Rick and I were 3/4 of the way there yesterday. And he was using a direct conversion receiver of his own design, with a PTO in an enclosure made from "flattened out tin-plated food tins." Fantastic! It was as if the radio gods had arranged all this to pull me out of the depths of parasitic despair! Thanks Rick! A video of his receiver picking up my BITX 20/40 appears above.

Pete and I will talk about the actual troubleshooting in the next podcast. I am HOPING to have it fixed by then. I may have to sacrifice some chickens to Papa Legba."

................

Bill,

I'm a long-time SolderSmoke podcast listener, and today one of my ham radio dreams came true.

I was listening to 40 meters today on my homebrew direct conversion receiver, and I heard your call. At first I didn't believe it was you, but there you were.

At first I just sat there dumbfounded, just listening, but soon realized that I should make a video of this "rare DX" (rare DX for me hi hi), and post it on YouTube for you to review.

My apologies for the low audio in the video. I was using my iPhone and its inboard mic leaves a lot to be desired, but the best audio of you is at 0:13, 0:50, and again at 2:12 into the video.

Heard you on 7.16 MHz, Sunday 2-22-2015 at 10:15 a.m. local east-coast time (15:15 UTC).

I'm located in Manchester Maryland (North - Central Maryland). My homebrew 40 meter rig is a PTO tuned direct conversion receiver with all discrete components. My antenna is a simple wire dipole about 6 feet above the ground just outside by workroom window.

Below are links to the YouTube video of your QSO , and the schematic the DSB transceiver that you were received on. The rig is one that I designed, based on the published works of many home-brewers from the web. I call it the Lakeside 40 (in homage to Peter Parker's Beach 40 transceiver).

So far I only completed the receiver section, and hope to complete the transmitter sometime this summer so I can use the rig at Lake Marburg (at Codorus State Park in PA), thus the "Lakeside" in the rig's name.

http://youtu.be/emsKg5n5-0c

http://www.remmepark.com/circuit6040/lakeside40.gif

73
Rick - N3FJZ

Bill,

Yes, what a coincidence with the PTO! That's the same WA6OTP PTO design
I based my PTO on.

I created a webpage tonight(very much a work in progress) so you can see
the details of how I constructed my PTO in the Lakeside 40, as well as
my rendition of a BITX 20. Click the [Permeability Tuned Oscillator], or
[My rendition of a Bitx 20] links on the left of the page.

The webpage is here:
[http://www.remmepark.com/circuit6040/index.html]

The ground plane for the Manhattan construction (and RF tight enclosure
for the PTO) are made from flattened out tin plated food cans, and the
coil-form for the PTO is cut from Masonite wall panel material with my
scroll saw.

Don't get discouraged from the less than enthusiastic response from the
others about your signal, pay them no mind; I'm sure they simply didn't
realize the significance of what it represented. To me, your signal was
the most perfect signal I have ever heard. It was perfect because I
know (from your pod-casts, and my attempts at homebrew) what it took for
it to be produced. Its existence, and the fact that I successfully
received it on my little homebrew rig too, represents the fundamental
core foundation of Amateur radio; experimentation, building equipment
with your own hands from scratch, expanding ones knowledge in the radio
art, and most important, having fun and enjoying the excitement that
comes from using gear that *you* built.

I cannot put into words how significant hearing your signal was for me
today - thank you! My biggest regret is that I didn't have a means of
transmitting yet on 40 meters, and my Bitx 20 is not ready yet,
perhaps in the future we can have homebrew to homebrew QSO's
where we can fine-tune our designs and tweak things (however we'll have
go above 7.175 MHz, or 14.225 MHz since I only hold a General ticket at
the moment).

Rick
N3FJZ.

PTO another view.

Rick's PTO

Sunday, February 22, 2015

Analog FOREVER! Menus are For Restaurants! Hardware Defined Radio! Chris's PTO

Beautiful! A Permeability Tuned Oscillator. No need for a fancy variable capacitor -- that brass screw moving into and out of the coil varies the inductance and the frequency. Collins style.

Feb 20 at 6:58 PM

I also wanted to send you a shot of what today's project has been. It's WA6OTP's PTO.
I bought the plastic tube/screw/bracket from Jim and I provided the rest.
This is a 40 meter PTO that covers the entire 40 meter band.
A little Q dope secured the windings.
Chris
KD4PBJ

WA6OTP has a very nice PTO kit:

http://www.wa6otp.com/pto.htm

And a lot more good radio info here:

http://www.wa6otp.com/radio.html

Friday, February 20, 2015

Italy, Spain, Gibraltar, a Flight to Prague, and How the Mighty Mite Really Works

Gab IZ1KSW is a true Knack-afflicted member of the International Brotherhood of Electronic Wizards: He is an Italian homebrewer who lives in Spain and works in Gibraltar. At the end of this e-mail exchange he has a great story about reading "SolderSmoke -- The Book" on a flight to Prague with his Greek girlfriend. It reminded me a bit of the problems I've had with fellow passengers while reading "Hot Iron" on the Washington DC train system.

A blog post about Gab's version of the Mighty Mite is here: http://soldersmoke.blogspot.com/2015/02/iz1ksws-italian-mighty-mite-video.html
His desire to REALLY understand the circuit is, I think, admirable. I know that my quick explanation of how the Mighty Mite circuit works isn't complete, and I'm sure that others will jump in with more details.

........................

Hi guys,

I write to you because I'm a bit lost.

Ok, the MMM is oscillating, brilliant!

Now I'd like to understand why it's working and how it's working.

I've been sitting on the workbench with the schematics in front of me and I found some resources on the internet, I've understood the concept of feedback loop but what really make me scratching my head is that I cannot match the MMM schematic with anyone of the typical oscillator design I found (Pierce, Colpitts, Hartley).

I've read online that it can be considered as a Pierce oscillator but from what I've found online I cannot find the purpose of the tapped coil. Maybe you can point me in the right direction before my GF starts complaining about the pile of schematics I'm accumulating in the living room!

Also, if you have any books to recommend, I'll be happy to go "back to the books"

Thank you and 73

Gab - IZ1KSW

.................

OK Gab. I've been meaning to do this. This little circuit needs some explanation. I'll take a shot:

Start by thinking of this circuit as an amplifier. The 27 ohm resistor from the emitter to ground (negative terminal) puts a limit on how much current will flow.

The 10K resistor from the base to the positive terminal puts a positive voltage on the base and biases it so that current will flow through the transistor.

Now the fun begins! It is an amplifier, but it has no input signal! The input signal is the output signal -- it is like a dog chasing his tail!

The crystal is very important. It is the main frequency determining element, and it is the conduit for the feedback that gets this thing oscillating. It is a piece of quartz. If you put a voltage across it, it will begin vibrating (physically) at a specific frequency. As it physically vibrates, it also creates electrical vibrations.

So, when you turn this thing on, noise in the circuit will put a bit of charge on the crystal. It will begin to ring, much like a musical tuning fork. The electrical vibrations from the crystal will go to the base. They will be amplified by the transistor and will emerge (stronger) from the collector. From the collector, they go to the 3.579 MHz tuned circuit formed by the big coil and the variable capacitor.

The coil wound on the film box serves several purposes. The portion of the coil between the positive terminal and the collector carries the 12V DC to the collector of the transistor. It also carries the amplified 3.579 MHz signal coming from the collector. This signal goes through the lower portion of the coil and causes the coil and the capacitor to resonate. The signal at the top of the tuned circuit peaks when the tuned circuit is tuned to.... 3.579 MHz.

The capacitor/coil tuned circuit (with the tapped coil) are set up so that the right amount of energy is fed back from the output to the input, and that this energy is fed back in the proper phase relationship to the signal at the input. Think of a child's swing at a park: To keep the swing oscillating, you have to push at the right moment (frequency and phase) and with the right amount of energy.

The little capacitor across the battery is to prevent "key clicks." The output coil on the main coil takes some of the energy and sends it to the antenna while converting the impedance of the antenna to a suitable "load" for the transistor.

Whew, how did I do? Lots of electronics and physics in those 7 parts!

73 Bill

................

Hi Guys,

Bills explanation is absolutely perfect –but there is some additional Math in the woodworks known as the Barkhausen criteria where kB = 1

see this http://link.springer.com/article/10.1007/s10470-008-9250-1#page-1

73’s

Pete N6QW

...............

Well, what can I say Bill? Grazie mille!!

I keep thinking that you would have been a great teacher, you have the rare ability to explain complicated concepts using simple words.

Yesterday I finished reading your book SolderSmoke GAWE (yes, you deserve an acronym too) and there have been several "eureka" moments while I was reading it. It gave me a lot of motivation to go in depth and understand what's going on in a circuit down to the physics of the components. I got the Kindle version but I'll order the paper version too, I love the hand make schematic and they're not very readable in the electronic version, plus I believe that a book about radio home brewing must be in the old fashioned paper version don't you think?

There's a funny story about the book. Few days ago I was on a flight to Prague with my YL, I was reading the book and zooming on the schematics to see them better, I was really into it and I didn't notice that the guy sitting on the seat next to me started to look at the kindle nervously, he probably though I was an bomb home brewer HI! So I decided to pass the Kindle to Angeliki so that she could read her books. She's Greek and she started reading a Greek book, written with the Greek alphabet which looks quite weird if you don't know it. At that point probably the guy thought to be sitting in the middle of some exotic terrorist... it was funny.

Wow... as most of the Italians do, I talked too much! Thanks again both for the big effort you make spreading the tribal knowledge with the podcast, the ARCI LBS articles and the books.

Siete fantastici!

IZ1KSW - Gab

Monday, February 16, 2015

SolderSmoke Podcast #172: Pete's New Rig, Bill's BITX 2040,Crystals, MMM, SNA jr.,Portable SDR, KX3!, W7ZOI at a 'fest, BANDSWEEP!

Pete and Ben's LBS Receiver

SolderSmoke Podcast #172 is available

http://soldersmoke.com/soldersmoke172.mp3

16 February 2015

Bench Reports:
Pete under the gun to finish SSB transceiver project. NEW VIDEO:
http://youtu.be/hbLXW0sHTFo
Bill fixes his BITX 2040 Oscillator (Bandsweep!)
Next: LP filter for 120 watt amp.
Bill's 13 dollar Chinese freq counter (Blue! With anti-wobble tape!)
Bill's next rig: Chipped to the Max, DDS, SBL-1s, plug in filters!
Radio Shack going under and JAN no longer making crystals.
Mighty Mite Project: Let's get them DONE!
An easy way to get Q or ESR measurements on crystals?
SI5351 as a crystal substitute.
DuWayne's Scalar Network Analyzer lights up the internet!
The Portable SDR rig -- Pete almost goes to the dumpster!
Report from the cutting edge: Pete's new Elecraft KX3.
MAILBAG: Meeting W7ZOI and WA7MLH at a hamfest.
Instant Messaging with Farhan

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

Sunday, February 15, 2015

World Radio Day! Article with Farhan

The Hindu did a nice article on World Radio Day. They wisely featured someone with a true case of The Knack, someone with a strong emotional connection to radio and radios: our friend Farhan.

http://www.thehindu.com/features/metroplus/thank-you-for-the-radio/article6886601.ece

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

Saturday, February 14, 2015

This Kid has THE KNACK TO THE MAX! And is in the International Brotherhood of Electronic Wizards! (VIDEO)

Oh man, we've all been there in one form or another. The struggle, the frustration, then, THE TRIUMPH! I love when his mother drops the plate.
Thanks to John KC0BMF

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

A Sweet Little Poem for Valentines Day

I was alone and all was dark

Beneath me and above
My life was full of volts and amps
But not the spark of love

But now that you are here with me
My heart is overjoyed
You've turned the square of my heart
Into a sinusoid

You load things from my memory
Onto my system bus
My life was once assembly code
It's now like C++

I love the way you solder things
My circuits you can fix
The voltage 'cross your diode is
much more than just point six

With your op-amps and resistors
You have built my integrator
I cannot survive without you
You're my function generator

You've changed my world, increased my gain
And made my math discreet
So now I'll end my poem here
Control, Alt, and Delete

You might not want to actually use any of that poetry today.
Sent in to us by Bob Crane, W8SX

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

Friday, February 13, 2015

SPARK FOREVER! George and Tommy Build a Spark Rig

It has been a while since I visited the Amateur Logic TV site. When I looked in last week I found George and Tommy building a spark transmitter. Pretty cool! The sparks begin to fly at about about the 23 minute point in this video. Very interesting. Way to go guys!

SPARK FOREVER! (You will see that emblazoned on the QSL cards of REAL old timers. They were railing against those newfangled Continuous Waves. There is a lesson in there for me... )

More AmateurLogic here: http://www.amateurlogic.com/downloads.htm

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

Thursday, February 12, 2015

Pete and Ben's "Let's Build Something" Reference Page

Lots of tribal knowledge here! That's the direct conversion receiver that forms phase 1 of Pete and Ben's "Let's Build Something" project. Arduinos! Si5351s! AD9850s! And it will morph into an SSB transceiver. Check it out:

http://www.jessystems.com/LBS_Detail.html

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

Wednesday, February 11, 2015

REALLY AMAZING! The Portable SDR Project! 42 Hours Left To Save It!

Holy cow! Look at that rig. The whole HF spectrum. AM, CW, SSB, Digital Modes, Waterfall display, GPS. It may even have a Vector Network Analyzer! (Deep breaths Pete Juliano, deep breaths!)

Michael KE7HIA is trying to get this project going via a Kickstarter campaign. He needs to get to $60,000 He currently has about $47,000 pledged. There are only 42 hours to go:

https://www.kickstarter.com/projects/1703258614/psdr-pocket-hf-sdr-transceiver-with-vna-and-gps

Wow, this rig would have been great for my Double A DR DX-pedition!

Features:

Coverage from 0 to 35MHz
Waterfall display that lets you see radio signals
Receives AM, USB (Upper Side Band), LSB (Lower Side Band), and Morse code (CW)
Modulates USB and LSB signals
Variable bandpass filter

Hardware:

Powerful ARM processor
Color LCD display
Dual DDS frequency Synthesizers
Quadrature Sampling Detector & Exciter
Digitally controllable instrumentation amplifiers
Morse Code key (the "Giblet" on the bottom right corner of the enclosure)
Magnitude & Phase measurement chip (for VNA and antenna analysis functions) with Impedance Bridge
Dual SMA connectors, smartphone style earphone/microphone connector, and USB port
GPS
Built in Microphone and Speaker
Internal Lithium Polymer battery with charger and high efficiency switching regulator
MicroSD slot
Pads for grabbing raw I/Q signals, both in and out.

Things it will be able to do with your help:

I designed the hardware to be capable of the following, but I can't write all the software myself. Please note that I can't guarantee when or if these functions will be added, or that they will work as desired.

Work as a full Vector Network Analyzer (VNA)
Work as a spectrum analyzer
Cover more modes, including digital modes and image modes
Work as an emergency location beacon
Antenna Analyzer
Frequency Synthesizer
Media player
E Reader / Picture viewer
Have improved audio
GPS Mapping navigation device
High end ARM development board
USB control of any features, including the possibility to operate the PSDR remotely. The USB port supports USB On-the-Go, making it possible to connect keyboards or other devices. Firmware updates will also be possible over USB.

Tuesday, February 10, 2015

Navassa Island 1972

The K1N DX-pedition is currently on Navassa Island (between Jamaica and Haiti). This made me think of one of my earliest ham radio memories: The 73 Magazine article on a 1972 operation on that island. Here is a short video on that trip. It is kind of wacky and fun.

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

Monday, February 9, 2015

Lucien's German Mighty Mite (Video)

Excellent Lucien! Thanks for sending this. I know what you mean about a project that doesn't work. It is rewarding and educational to figure out where you went wrong. I knew a guy who would ask, at a hamfest, "Does this rig work?" If the the seller admitted that it didn't, he'd reply, "Good, I pay extra for that!" He liked the challenge of fixing it. Of course, there are limits to this, and sometimes these challenges will make you wish you had taken up stamp collecting.

Hi Bill and Pete,

For me too, it's a happy day - I got the Mighty Mite working! Thank you so much for the inspiration to get into homebrewing...

I'm just licensed for a year now and this was my very first project (except for 2 basic kits that I build) and it really was a great learning experience. The best part: Since it didn't work out "plug'n play", I had to debug the thing and actually start thinking - so I put 2 caps in parallel instead of the wrong one I had used (I found them in a little box some guys at a hamfest gave me for free - never thought I would ever use something from it...). And I had to use the voltmeter to look for a short circuit. Basic stuff, but for me, this was a breakthrough!

Here are some more things I learned during this first project (don't laugh):

Where the heck do I plug stuff that's supposed to go to "ground" in? Now I know: usually to the negative pole!
When 2 lines cross in a schematic, that doesn't mean there's a connection!
How do these ready-made breadboards actually work? Had to try out...
It's important to think about the actual layout beforehand!
When debugging, trial and error doesn't help.
There's yet another crazy foreign unit called "gauge"! (I used smaller magnet wire than recommended, it still seems to work...)
9V-blocks get VERY hot when shorted for a minute or so!

Attached is an image of my ugly prototype, now I want to give it a better "home"... And here is a little video, demonstrating that it works, inspired by IZ1KSW:

https://www.youtube.com/watch?v=lxXyAb_np8I&feature=youtu.be

BTW, frequency is about 3,5793 Mhz.

Thanks again for all the great inspiration and vy 73 from Germany,

Lucien / DH7LM

IZ1KSW's Italian Mighty Mite (Video)

Hi Bill and Pete,

This is a great day for me!

I just managed to get my MMM oscillating!

This is my very first homebrew project guys and I'm so excited! I started from scratch... and when I say from scratch, I mean that I didn't even have one of the 7 components required, no PCB boards, no junkbox, nothing... just the soldering iron and the will to "build something".

Thanks to Pete suggestions I managed to put some components together and now I have a (small) junkbox (I'm very proud of it) and thanks to soldersmoke I entered the ranks of the homebrewers.

I send you also a couple of pictures, I used Manhattan style and I found it very useful to understand the circuit. It's far from being a clean and neat building but it's a first step.

I'm looking forward for the next one!

73 de
IZ1KSW / EA7JUG - Gab

Sunday, February 8, 2015

Glowing Blue Numerals! A Frequency Counter for the BITX17 (VIDEO)

These little frequency counters from China have a lot of potential. And they add a dash of digital color to an otherwise bland analog hamshack. I got mine on e-bay.

My BITX17 has now been "accessorized" with
1) A rotatable Moxon antenna (big improvment!)
2) A 120 watt Communications Concepts Linear amplifier (another big improvement) and
3) This digital frequency readout.

What next?

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

Saturday, February 7, 2015

DuWayne's Scalar Network Analyzer -- In an Altoids Tin!

DuWayne (KV4QB) has done something very cool here. He's taken an Arduino Nano, a cheap AD9850 DDS board, a small screen, and a couple of log detectors, and he has built IN AN ALTOIDS TIN a scalar network analyzer that lets you see the bandpass of a filter. (We posted an earlier version of this here: http://soldersmoke.blogspot.com/2015/01/duwaynes-ad9850-arduino-tft-swr-scanner.html ) Wow. I've been doing this by hand, changing the input freq at 100Hz increments, measuring the output, putting the results into a spread sheet, converting to log (db), creating a graph... DuWayne makes it a lot easier. DuWayne is being encouraged to write up the results, possibly for QRP Quarterly.

Hi Guys
Started playing around with the SWR scanner that I had been working on. Waned to see how hard it would be to make a very simple scalar network analyzer out of what I had. Really wanted something small to use for checking bandpass other filters. Hoped to get about 30 db. of range ,which should be enough for most filters. I have a couple of 8307 log detectors, but was afraid that it would be a pain getting it working and shielded in an Altoids tin along with the rest of the circuitry. Went with something even easier than the resistive SWR bridge I already had. Replaced the bridge with two basic diode RF probes, and changed the amplifiers so I could adjust the gain. I use one to measure the direct output of the 9850 DDS module, and the other for the output of the device under test. Kept the same control function as in the SWR scanner. A short push on the encoder button starts a sweep of the selected band. Holding it down for over a second cycles through the bands. Once a scan is done you can use the encoder to scroll through the sweep. I display the frequency and iDUT value in db relative to the output of the DDS module. The USB connector is available and different start and stop frequencies can be entered if needed when working with IF stages.

Well it worked much better than I had expected. After a simple adjustment of the amp gains with the output looped directly to the input, I was getting nearly 50 db with the loopback removed. Just using some standard value resistors, in a pi attenuator I got a very nice looking sweep that was within a couple db of the 40 db i had built it for. Since I only used standard value resistors, I though this was good enough.

Then I used ELSIE to design a 14mhz lowpass filter, again used standard values for L and C that I had on hand . Really happy with the results I got.

Finally I grabbed 3 crystals out of a bag without checking frequency or other parameters, I threw together a basic crystal filter. Used the USB interface to set the sweep range, I was really really really pleased with the results I was able to obtain.

The software still needs a little tweaking and a couple of additional functions I want to add, but I think this will be a very nice tool. Plan on giving it a try when I build Pete's Lets Build Something transceiver. Amazing what you can stick in Altoids tins, even if you have to stack two so you can include a battery pack .

Attaching some pictures of the progress so far. As you can see that with what I used to build the test fixtures, I am amazed that they even worked at all.
73 DuWayne