SolderSmoke #171 DC RX in QQ, Power Supplies, Small Screens, 12 Buck Counters, HW8 Error?, KX3 RX

SolderSmoke Podcast #171 is available: 

http://soldersmoke.com/soldersmoke171.mp3

Bench Report: 
Pete's Small Screens (in Color!) 
Si5351s
Bill's Graph Paper Frequency Readout
Bill's Broadened Barebones Barbados RX.  DIGITIZED! 
Another AD9850 DDS using M0XPD Kanga UK Shield
New 13 dollar Color Display (Prettier than Graph paper!) 

Pete and Ben's Article in QRP Quarterly Available free here: 
http://www.qrparci.org/qqsample/qqsample.pdf

The DEEP SPIRITUAL REWARDS of DC Receivers 
The Importance of Good Power Supplies
SPRAT Article on HW8 Design Error
Latest Edition of Hot Iron
Elecraft KX3 -- Has one of the best receivers in the world  

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

15% Off on SolderSmoke and other books at Lulu This Weekend

All three of my books are here:  

http://www.lulu.com/spotlight/soldersmoke

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

More Glowing Numerals! BIG! BLUE! $13!

Even though my pencil and graph paper frequency readout for the BITX rigs has its own undeniable charm, this little device could get me to go digital.  I heard about it from Chuck Adams and the folks on the qrp-tech mailing list.  13 dollars.  It covers .1 MHz to 2.4 GHz.  You just hook up a 9 volt source and the RF input.   It also does IF offset.  The construction looks great and it would be very easy to put into (or aside) any rig.   Here is where I got mine: 

http://www.ebay.com/itm/400732593471?_trksid=p2060778.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

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

Beagle 2 Found On Mars

I was one of the millions of people who woke up that Christmas morning in 2003  thinking not of Santa Claus but of Colin Pillinger's Mars Lander, the Beagle 2.  We were in London by then, and later on I got to meet Colin Pillinger.  I still have the books about Beagle 2 that he gave to me.   Wow, it looks like they came very close.  Too bad Colin did not live to see these pictures. 

The Planetary Society has a very good article on all this:  

http://www.planetary.org/blogs/emily-lakdawalla/2015/01160800-beagle-2-found.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

Back Into the Digital Morass

Using a very nice M0XPD AD9860 shield from Kanga-UK and software by Richard AD7C I put together another little DDS VFO.  This one went together without a lot of hair pulling.  I put the LCD, brightness control and rotary controller on one piece of vero board -- this will also serve as the front panel.  

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

The Battery That's Been Working for 175 Years

In case you missed this.  Makes you think, doesn't it?  I'm thinking of a QRPp QRSS transmitter that would just keep on going.  Battery designed by Giuseppe Zamboni.  

http://motherboard.vice.com/read/this-battery-has-lasted-175-years-and-no-one-knows-how

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

New Analog Frequency Readout for BITX17 VXO

I've been getting tired of being in the dark about the frequency on which my BITX17 was operating.  So I pulled out some graph paper, my frequency counter, and a pencil.  You will see two frequencies at each point -- that's because  I use two crystals, switched by the black knob on the left.  I realize this paper and pencil approach is hopelessly out of date, but I see it as "appropriate technology" for a discrete component all-analog transceiver.  

Pete set me straight on how to come up with the numbers: VXO frequency minus  ACTUAL carrier oscillator/BFO freq.  After doing this I took great delight in going on the air and asking guys with fancy "glowing numerals" rigs to compare their freq readout with my pencil and graph paper readouts: they were painfully close.    

But I am not slipping completely into stubborn Luddite-ism; this weekend I worked on a DDS-based AD9850/Arduino VFO with I-Q output based on Paul M0XPD's Kanga-UK Arduino Shield.   STAY TUNED! 

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

Jailed for The Knack: Gerry Wells, Homebrew Hero

Thanks to Thomas of the "SWLing Post" for alerting us to the story of UK radio legend Gerry Wells. As Thomas said in his post, you really need to drop what you are doing and listen to this great BBC program about Gerry: 

http://swling.com/blog/2011/02/radio-documentary-the-wireless-world-of-gerry-wells/

The poor fellow was actually JAILED for his "radio obsession."  Wow.  That was kind of harsh.  But Gerry overcame adversity and had a very happy life in radio.  

Thomas has more on Gerry here: 

http://swling.com/blog/2014/12/jonathans-interviews-with-gerry-wells/

Thanks Thomas!  And thanks to the BBC. 

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

VE3MKC's Teensy Si5351 SDR Receiver with a Tiny Color Screen (video)

From: Rich 

To: "soldersmoke@yahoo.com"  
Sent: Thursday, January 22, 2015 9:22 AM
Subject: Cheap, open source Arduino SDR project

Bill

First, thanks for Soldersmoke and all you do for us QRP hackers around the world. I'm a big fan!

I've detected you are getting sucked into the world of microcontrollers of late. I know you are not really that excited about SDR but this is a radio that combines Arduino, the currently popular SI5351 and a Softrock to make a very functional SDR. I started this project last year which uses the fabulous Teensy 3.1 and companion audio shield. I recently packaged it all up and it looks like a QRP radio now. Still doesn't transmit but as I like to say thats "just a small matter of software".

There are several posts about it on my blog. The most recent:

http://rheslip.blogspot.ca/2015/01/teesy-sdr-project-update.html

There's a link to a video and a link to the code in that post.

Rock on Bill!

73, Rich Heslip

VE3MKC

From: solder smoke

Sent: Friday, January 23, 2015 4:09 AM

To: 

Subject: Re: Cheap, open source Arduino SDR project

Wow Rich that is really beautiful.  Amazing!   I am also sending this to Pete Juliano, but I was at first hesitant about this because I feared that your combination of Si5351 and TFT display might be TOO exciting for him. Deep breaths Pete...  

73 and Thanks,  Bill 

From: jessystems@verizon.net
To: soldersmoke@yahoo.com; 
Subject: Re: Cheap, open source Arduino SDR project
Date: Fri, 23 Jan 2015 06:03:40 -0800

Hi Rich & Bill,

Wow –really exciting project Rich! Congratulations and Bravo!

This is so exciting, for all hams, as this just shows the power of the available low cost technology that is now on the market. Your project is really tempting as I have a V6.2 15M softrock sitting in a box (somewhere). I was somewhat put off with the Power SDR as the opposite sideband rejection is not too good –it is clear you have cracked that nut.

Thanks for sharing Rich and yes Bill I am taking very deep breaths.

73’s

Pete N6QW

  

• Jan 23 at 9:27 AM

• Pete Juliano
• me

Thanks guys! When I saw the Teensy 3.1 with the companion audio codec board the first thing that came to mind was a portable SDR. Since its Arduino compatible I am able to leverage the SI5351 library, encoder library etc so its mostly just putting software blocks together. The digital filter design is a bit tricky but Loftur VE2LJX did quite a bit of work on that and now it works really well.

I hope to add CW decoding and PSK31 at some point. I've used less than half the flash on the Teensy so lots of room for new features. I'm hoping if the word gets out I won't have to do this all myself!

Pete - too bad you missed the Black Friday sale - Teensy 3.1 and the audio shield for $18. Deep breaths... 

: )

73, Rich

VE3MKC

---

---

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DuWayne's AD9850 Arduino TFT SWR Scanner

This is really nice.   DuWayne KQ4VB, has been talking to Pete about his use of digital chips, Arduinos and TFT displays in homebrew SWR analyzers.   Obviously these techniques could be used to measure the passband of crystal filters.  (Far superior to my pencil and paper procedures.)  Nice work DuWayne!

Pete
Looks good, I did some playing with the TFT board I have.  Did a board for the antenna analyzer using the TFT and a 9850 DDS module insted of the NOKIA and si5351.  Wanted to see if there was much difference between a sine wave out and the square wave from the 5351.  Appears to be very nearly the same from a couple of quick tests I have done.  Want to try some different diodes and change some values for amplifier gain.
Will keep you informed. DuWayne

Earlier... (4 November 2014)

Pete
Really enjoy listening to you on Solder-Smoke.  Saw the link to your
xcvr with the Adafruit si5351 board.  I got a couple of them and have
been playing with code for them.  Have been spending most of my time
working on an antenna analyzer based on the one by K6BEZ. Pleased to see
your article in the latest QQ.  I have used basically the same circuit,
except am using  the little NOKIA LCD display. The resolution is not the
greatest  but works well for this application.  I am using some of the
original code from K6BEZ to talk with his existing PC program.  For
stand alone I have 2 modes, a straight tune mode where I can select the
frequency and read the SWR.  Also implementing a sweep mode that scans
the whole band and after it is finished you can tune across and see the
frequency and SWR.  I am attaching a couple of pictures of what I have
so far. Waiting on the correct op amp to arrive and making some changes
to the amp gain to get better results on the higher band where the
output of the DDS drops off.
Thanks for all the inspiration you give to us home builders and tinkerers
out here.
73 DuWayne   KV4QB

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

Interesting Propagation Web Site

CONUS HF BAND CONDX

1/22/15 --- 10:45:00 GMT --- REPORT # 1289

160 80 40 30 20 15 10

I think this is a really interesting and useful way to gather and present information on propagation conditions.   Check it out.   The "instructions" page gives some background info on the technique used. 

http://www.bandconditions.com/ 

The author, Biz, K5BIZ seems like a very FB ham: http://www.qrz.com/db/K5BIZ

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

Star City Antique Radio's Beautiful Workshop

Dale Cook of Star City Antique Radios and Test Gear has a really nice site with great pictures of his workbenches and test gear.  Inspirational stuff.  Take a look: 

http://plymouthcolony.net/starcity/radios/pages/compact.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

All of the Shortwave Spectrum LIVE on Web Waterfall Display

It's been a while since I checked in with this site.  They have made a lot of improvements.  It is very impressive.  I had trouble with it using Internet Explorer, but it worked right away using the Google Chrome browser.   Play with it a bit.  Zoom in on 40 meters.  Listen to the LSB contacts.  Very nice. 

http://websdr.ewi.utwente.nl:8901/


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When Your Local Oscillator Could Sink Your Ship!

Thomas KK6AHT is the intrepid radio amateur from France who moved to California and successfully built a Minima as his first homebrew project.  Yesterday we got additional evidence that Thomas definitely has THE KNACK.  It seems that he has been looking through really old radio magazines (clearly a symptom).  He sent us this add from 1942.  Yikes!  Imagine getting your ship sunk because your Local Oscillator is not quite local enough!  

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

Hey!

I thought you would get a kick out of this 1942 ad. Sounds like those guys had a some good reasons to fight QRM ... Who knew the important role played by the FCC during the war?

Now tell me: why were the receivers so noisy at the beginning of the war? What did they change? Happy new year to you both! May the gods of radio (and digital) bring you much fun on the air.

73, Thomas  

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

Good to hear from you Thomas.  Long time no hear -- I was beginning to fear that you had grown disillusioned with homebrewing and had switched to stamp collecting or something else less frustrating.

As for the ship radios, two things come to mind.  Some of them may still have been using regens at the start of the war.  If so, that was kind of suicidal -- regens radiate!  The detector moves in and out of oscillation (sometimes staying in oscillation) at the receive freq.  The Germans were quite good at detecting and direction-finding these signals, on land and at sea.   So the regens would have to go.

Superhets are not quite as bad, but they too can radiate.  My Bitx spills out a bit of signal at 23 MHz (VFO) and at 5 MHz (BFO).  Without adequate shielding, these sigs could also be detected and triangulated.   Looks like the radio in the picture had lots of shielding. 

We watched a French movie last night:  The French Minister.  A comedy about life in the French Foreign Ministry.   It was kind of fun.

What are you working on?   I am listening to 17 meters using an OLD superhet in which I have replaced the VFO with an Arduino/DDS generator.   Works great but the display is making lots of noise. 

73  Bill 

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

Hi Thomas,

Well Thomas, I will dip my toe into some very deep water and attempt an answer for you which also is an important clue about QRP operations.

1. Today we have many many signals co-existing in the radio spectrum. During the war there was much less radio garbage and the military lit up the ether with transmissions very sparingly. But that is on the transmit side. That said the local oscillators (much like you have with the Si-570 on your Minima) used in receivers also produce RF that unless is minimized in some fashion is passed right through to the antenna and can be detected. Regenerative receivers are especially prone to this. Yes some military equipment used regenerative receivers. In fact the famous Paraset had to be constantly moved so it would not be detected.
2. This receiver generated RF into the antenna was addressed by companies like Scott by shielding everything. That receiver in the photo probably weighed about a 100 pounds or more. Much attention was paid to RF bypassing and grounding. The cheap table top radios were RF generators par excellence.
3. There was another approach developed in WWII to solve that problem and forms the basis of what makes work that little device sitting in your pocket. The odd part it was invented by a famous movie star. Look up Heddy Lamar in wikipedia. She and a co-inventor came up with the concept of frequency hopping and spread spectrum technology. By jumping frequencies it would be hard to pinpoint a transmitting station. That concept forms the backbone of our cellphone system
4. Now the QRP part – if the RF output from a receiver local oscillator (milliwatts) can be detected from afar – then it follows QRP works!

Have fun. 

Pete

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Digitizing the Barebones Superhet

I did this for Pete.  And I did it to start out the new year with something different.  And because I needed the crystal for my beloved BITX and didn't want to buy more crystals. 

After successfully broadening the filter in my Barebones Barbados Superhet (originally built by Dale Parfiit W4OP) I decided to replace the VXO with an outboard Arduino/DDS device. Nothing new in that  (I was playing with this back in October), but in what I think is a symbolically significant twist, I pulled out the tuning cap for the VXO and, in the hole left by the tuning control, replaced the knob with a BNC connector.  That connector now carries DDS signals into the receiver.  The crystal was at around 23.125 MHz -- that's why the LCD display is showing 23 MHz.  

It works great.   I was listening to the DX station in Iran this morning.  

Here is a video of the October 2014 experiments: 


   

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Colin Finishes His BITX

Wow, that is one beautiful BITX.  Nicely done Colin.  But I must say that you are exhibiting an almost inhuman degree of patience!  Who needs a case?  Fire that thing up and make the traditional "still-on-the-workbench" initial contact. 

Hi Guys,

I loved the last SolderSmoke, it was another great episode. It really does amaze me, that a few years ago, hams were saying that it was too difficult to build your own gear that would be anywhere near to the commercial stuff, but here we are with Arduinos etc bringing powerful functionality to the masses. I couldn't have imagined building an SSB rig with a pretty and functional LCD screen when I started in ham radio.

Bill, first regens, now SDRs? Amazing! I exchanged a few words with George Dobbs about your change of heart towards regenerative receivers, he seemed genuinely pleased. :)

Pete, your Si5351 work with the pretty displays is cool, I can see me getting pretty hooked! I have the Si5351 board, Paul M0XPD advised me to buy it. I'd love to build another SSB rig in a smaller box for regular SOTA activating. I must look into the pretty little displays and have a play with the Si5351. I notice that Hans Summers has now put out a cheap Si5351 based kit, handy for us guys in Eu. http://www.hanssummers.com/synth.html

I finished building my BITX board yesterday but wanted to have a sleep before applying power! Today I carefully checked the circuit for errors and found none, phew! I fired the rig up gently, watching the current carefully. I wound up the TX bias to 50mA as stated in the MKARS80 instructions, all went well. I plugged in the mic and spoke - BANG! - Everything went off. Oops - I had used a 500mA fuse for initial safety and forgot to swap it for the bigger one! I fitted a 1.6A fuse and hey presto, all was fine. I was absolutely amazed and to be honest, rather proud of myself. I think the TX is a little bit too hot, my meter is showing about 6W on voice peaks- eek! The rig seems to be perfectly behaved though, no wierd effects seem to be happening. I can just turn the bias down a bit, right?

Anyway, I was happy with my progress so I finished for the day. I still need to investigate and probably tweak the carrier suppression.

I spent a short while talking into a dummy load, using my FT817 to monitor the transmission. My 2yr old son was interested in my voice coming out of the 817'sspeaker!

Thanks for all the guidance and help along the way, I'm elated that I've built a voice rig that works! I've attached a pic of my finished board, I only just squeezed the circuit on, but isn't she pretty? :-)

Can't wait to get the rig built into it's case and score that first QSO.

73, Colin, M1BUU

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Kansas Mighty Mite

Greetings Bill

I have been a bit ill,  but finally found some time to work on my Meara Mighty Mite, which i wish to call it as it was by the grace of Bill Meara that I am able to play a part in the Colorburst Revolution could begin.

I just wanted to share some pictures from the bench of my progress, which is not yet fit for the ether.

I originally wanted to build a really unique design. I have a tendency to complicate things. The more simple it is, the more complicated I tend to make it. After a lot ambitious failed starts, I decided that the best thing to do is to keep it simple. In fact, I would say that I was "over-noodling" this one. So I just started building.

I use copper clad PCB, which I get for very cheap from an ebay seller named abcfab. I use a tool I made to cut islands by hand. Information can be found about this method on my blog.

I am almost embarrassed to share photos of my build, especially after seeing such wonderful designs as you have featured on the webpage. But the excitement is just to great, so here it goes:

I build ugly circuits and I'm proud of it.

I haven't build the LPF yet and wouldn't put it on the air without one. 

Thanks for all the great inspiration and for inspiring a revolution of colorburst liberation!

I want to share something from Solid State Design for the Radio Amateur, W7ZOI & W1FB, page 19

"All of the circuits shown are aimed at reasonable stability, but have relatively low output power. It is possible to bias many of these circuits higher to obtain outputs of up to perhaps 1/4 watt. However, thermal stability is often severely degraded, chirp is introduced if the oscillator is keyed, and the user stands a chance of damaging the crystal from excessive rf current. It is not recommended that a single oscillator stage be used as a simple transmitter. The addition of an amplifier is so straightforward, and the system efficiency is so much better, that the minimal simplicity is not of value."

That may be true, but the Mighty Mite is for learning and getting our feet wet. Still it may be interesting to point the above out or talk about it.

Also, I'm curious to know which schematics everyone is using. The famous Easy QRP transmitter on the QSL page, perhaps DeMaw's from QRP notebook (available on archive.org in pdf form for free).

73, keep your iron hot and stay fluxy,

-KE0BFF, Lawrence KS.

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Pete's Beautiful Tiny Color Display

Oh man, this is the kind of thing that lures me ever deeper into the digital morass.  That would be hard to do with my beloved discrete analog circuits!    Be sure to note the size (it is sitting on the top from a pill bottle -- you can also look at the pen for a size reference). It is 1.25 inches by 1.25 inches.  Pete has it working with the Si5351 software.  As you can see there is still room at the bottom of the display.  Pete notes that an SWR readout is possible.  And Pete got this device for FIVE BUCKS! 

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

Broadening the Barebones Barbados Receiver

I've been working on the crystal filter of the Barbados Barebones Superhet receiver.  This was designed by Doug DeMaw in 1982.  This one was built by Dale Parfitt W4OP and then repeatedly modified by me.  It is now on 17 meters with a crystal-switchable VXO.    Earlier I had made a very crude attempt to broaden the filter from its original very narrow CW configuration.    This week I did this again, but this time I actually characterized the crystals and used Wes's LDA and GPLA software (from EMRFD) to design the filter.  

I played with the capacitor values and finally got the 3 kc bandwidth I wanted, but I'm having trouble getting rid of the ripple.   I know this is dependent on the impedances at the two ends.  The programs say I need 2000 ohms.   

I'm kind of puzzled about how Doug DeMaw did this with his original design.  For his crystals and his 250 Hz (!) bandwidth he said he needed 450 ohms.   He used 4.7:1 turns ratio transformers at either end and said that by putting 10k resistors across these transformers he got the needed impedance.  I can see how this would work looking into the gate of the 40673 IF amp, but looking back at the drain of the 40673 mixer, I'm not so sure that that would yield 10k. (See schematic below.)

But who am I to doubt Doug?   So I assumed he was correct about the 10K and I re-wound the transformers with a 2:1 turns ratio, thinking that would get me closer to the needed 2k.   But the ripple is still there.  I guess I could use a return loss bridge at this point... 

I don't know whether this is worth messing with anymore.  The receiver sounds nice.  The 3kHz bandwidth gives it a nice sound, and the ripple doesn't seem to be noticeable  That FAR circuits board is tightly packed and difficult to work with.  So, should I leave good enough alone, or should I proceed with fanatical ripple eradication.  Any advice?

BTW:  Why is it that receivers always seem to sound better when opened up (as above) on the workbench?  

 

 


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Kai's Redwood Mighty Mite with Poker-Chip Hacksaw Key

And Check out Kai's homebrew key:

Hi Pete,

 

  Thanks for your kind words.  I really enjoyed the MMM project, first analog oscillation .  Your right about the homebrew key being a hacksaw blade and a few pieces of plywood.  The knob is an old poker chip.  You can adjust the spring tention by moving the blade in and out of the plywood.  Travel can be adjusted by raising and lowering the bolt under the blade.  I needed something for CW and wanted to stick to the ham maker thing.  As for me sending lefty, I do that so I can switch when the right gets tired or I need to hold ipod for video.  Thanks for what you add to soldersmoke.  73.

 

Kai

Ps I will send picture of key.

On Monday, January 12, 2015, Pete Juliano <jessystems@verizon.net> wrote:

Hi Bill,

 

Wow –so cool! I was impressed with not only his M^3 but the homebrew key and sending with his left hand.

 

It would be nice for Kai to send us his details for the key.  It looked like a hacksaw blade sandwiched between some plywood blocks of wood and some sort of plastic tuning knob from a defunct transistor radio as the key knob. Now that is what I call homebrew –elegant and it works well!

 

73’s

Pete N6QW

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

SolderSmoke Podcast #170 Double A DX-pedition, SI5351, Mighty Mites, Phasing Dreams

SolderSmoke Podcast #170 is available: 

http://soldersmoke.com/soldersmoke170.mp3

Bill's Double A, DSB, Dipole, Dominican DX-pedition.  
             Living the "How's DX?" Dream
Seeing the Southern Cross with Soviet Binoculars
Pete goes remote 
SI5351 a chip with a lot of potential
Pete's experiments with Nokia LCD displays 
Michigan Mighty Mites around the world
               The Postal Stream Roller
Steve Silverman's very kind variable cap offer
MOXON modeling with EZNEC
Aspirations for 2015

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

"Gentlemen, We have Oscillation!" Jacob's California Mighty Mite

Bill and Pete,

I bring news of the California Mighty Mite as Bill dubbed it.

I repeated the steps as documented in version two with Pete's parts. I had one hiccup. I was winding L1 with Pete's red wire when, on turn 42, I ran out. Luckily a search of the workroom revealed the last two coils of radio shack magnet wire that I bought with the Gold wire. I checked the thickness of the Green-coated wire and found it to be one gauge smaller than Pete's wire. To be ready in time for the podcast, the green wire would have to do. It was fussier that the larger gauge wires, but with my trusty electrical tape, the L1 coil stayed on the coil-form quite neatly. Using a scrap of gold wire, I wound L2 making sure to tape it evenly spaced.

Next I remeasured each of the parts to be soldered and arranged them in according to the Schematic. With the Soldering iron hot from warming while I would the coil, I detached the 365pf varicap from the MMv2. I strapped on the heatsink to the 2N3058 transistor and soldered the 27Ohm resistor to the Emitter. I attached one pole of the Colorburst crystal to the solder tab on the varicap along with the stripped end of L1 coil. I soldered the Collector to the Tap-2 of the L1 coil, then the Base to the other pole of the crystal. I then attached the 10k resistor to the base and attached another red-magnet wire to the side of the varicap. Almost done I looped a 47nF ceramic capacitor to the  2 power posts of a DC connector, then wrapped the Tap-1, 10k, and the lead from the varicap into the pin (positive) solder tab of the DC connector. I took a second red scrap and stripped the ends, stuck it in the sleeve (negative) solder tab.

Two applications of solder later, the multimeter was back out for a final continuity check. After checking across every joint, I plugged in my power supply to the Mighty Mite. Reaching over to the shortwave I leaned in the power button and tapped in the Colorburst frequency, 3-5-7-9. Static filled the room as I made sure the radio was how I left it earlier that week. SSB mode, attenuator off, and volume up. My finger tingled as caressed the straight key, now wired to the resistor and negative line. I was scared something would melt or flame up when I keyed down. Well no way to find out, except to do.

 The key spring resisted, but I felt metal below as the key bottomed out. The radio let out a sound like rubber going down a slide and faded as I held down the key.

Gentlemen, we have Oscillation.

Revision 3 was a success. Version 1 being breadboard and Version 2 being Bill's crystal and what I had on hand.

I tried tapping out CQ, but was faced with the chirping fact that I haven't practiced in a year. I don't even know TEST let alone CQ CQ KK6JTL TEST. I turned the varicap to see if the sick squeal got any better with adjustment. It did and the pitch out of the radio changed after a bit. I must be changing frequencies! I spun around and fired up the computer. The RTL-SDR would show me what I was doing and who may respond, along with who I might be interfering with.

With the waterfall display zoomed in, showing about 5kHz around 3579kHz, I went back to the Mighty Mite. I saw one CW QSO going on in 3575kHz and two other spikes at 3576-3578kHz. Any guess at what those are? I knew since Sunday night I had been listening to JT65-HF. I reached over and held the key down. A big red spike went up at 3576.5kHz

I waited for quiet and keyed down. I turned the varicap to lower the capacitance. The spike moved to a higher frequency. When the varicap was half out, the squeal began to sound like a tone again. Problem was I was still at 3578kHz and still stepping on the JT65 signals. I called my wife in in excitement to show her and asked her to help me tune the circuit to the official frequency. I'm going to leave the varicap there for now. So I start it at 3577 and have to dial it back to 3579 to operate. I can almost go to 3580 with this little Mighty Mite.

Finally I was curious. I had forgotten to check the output of the transistor Pete sent me on my LC meter. So I got the datasheet from the Internet. The BC547A I had used in Versions 1 & 2 were rated for 325mW. The 2N3058 is rated for 5W. Pete, how much power does this put into an antenna when fed with 12V? Apparently not enough to wake my Radioshack SWR/Power meter. But that thing is hungry. It needs more than 2 Watts for it to function correctly.

Pictures attached. The transistor heatsink looks like it it touching the varicap in the pictures but I made sure there is plenty of gap. Too bad none of the pictures of that gap turned out. The wiggle in the waterfall picture is due to me turning the varicap to show range. Pete left a grounding wire on the case of the crystal. I chose not to remove it, but did not attach it to anything.

Congratulations Jacob!  You really hung in there, overcoming obstacles including the US Postal Service's Crystal-Crushing Steam Roller.  The rig looks great! 



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Irish Mighty Mite

Hi Bill and Pete,

I couldn't stand it any longer, listening to you guys on the podcast and seeing all the Mighty Mites being built I had to have a go myself.  Concerned that I might plunge Soldersmoke into receivership if I asked for a free crystal to be posted to Ireland I used a 3.560MHz one, recently purchased from the GQRP club store.

2 amazing things happened when I was building it.

1) for the first time ever I had all the parts I needed in my junk box.  Since getting my licence in 2012 I've been gradually collecting and buying components.  It's so much easier when you find everything you need.

2) for the first time ever it worked straight away.  When I finished the last component I heard this voice from over my shoulder, it was Pete saying "Now go and noodle through the circuit and check your work"  Sure enough I'd missed one of the connections and everything else checked out ok.

So I plugged it in, hid behind the shack chair and turned it on.  Success!!!

Keep up the good work both of you!

73 de Chris EI6KH
Licensed since November 2012
Fists UK Member #15966
G-QRP Member #13730
Phoenix Radio Club Member
IRTS Member
MLS: IO63jk

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

W5RST's Mighty Mite + CQ article on Super Mite

I think Mike's MMM looks fine!   The CQ article he refers to has some very interesting ideas.   Here it is:  http://soldersmoke.com/SuperMite.pdf

Hi Bill (and Pete),

Well, mine is not as pretty as Chuck’s, but I put one together last weekend, too.  Before I added the lowpass filter, the output looked pretty ugly on the scope, but afterwards it was OK.  Mine puts out about 200 mW on 80 M. I’m thinking of trying the power modification from CQ to boost the power a bit (attached):  when you’re competing with W1AW on 3.5815, it can’t hurt! Sorry for the iPhone quality pictures...

73,

Mike

Michael McShan W5RST

Oklahoma City, OK

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