W2DLH's 20 meter Mighty Mite

N2CQR & N6QW,

 

I ran across a reference to the SolderSmoke book and read through it very quickly.  Through the book, I discovered the SolderSmoke podcast and have been enjoying every minute!

 

I just want to thank the two of you for the inspiration and new motivation I’ve found in a hobby I’ve loved for 25 years!  I’ve never tried homebrewing anything but that’s about to change.

 

It took me a while but we have oscillations on or about 14.060 MHz!

http://youtu.be/AUms45rwm84

I adjusted the circuit to use resistor divider biasing of the 2N2219 and changes to the biasing and coil to accommodate the 20m crystal. Also the only cap I had that worked was a 10-50pF trimmer. Aside from my placing the crystal in the wrong point in the circuit because I wasn't paying attention, this Michigan Mighty Mite needed minimal tweeting. The antenna is a 50 ohm resistor which the KX3 heard very well with its attenuator in line. 

 

Now my problem is that I listen to SolderSmoke in the car and it's bad form to take notes and drive at the same time. Also, I find myself wanting to experiment with all of the ideas from the podcast at once...  If I build your LBS in modules, Pete, then I can experiment later and swap circuits to my hearts content.

 

One question for now...where is a good source of plentiful, inexpensive crystals?

 

Thanks again, guys!

 

Darryl Hambly, W2DLH

- - - - - - - -

Grid DM78pu

G-QRP 15014
QRP ARCI 15138
SKCC 10990
- - - - - - - -http://www.qrz.com/db/W2DLH

Waco Mighty Mite Mojo!

Eric:  Wow, great news from Waco.  JOO indeed!  And I really liked the WAY you did it, liberating crystals and wire from old TVs.   That definitely adds mojo to the Waco M^3.  Bill

 

Hello Bill,

  My name is Eric Melling KD0OXY. I have, as of tonight, officially passed selection for the CLA. My Michigan Mighty Mite began oscillating tonight between 1830 and 1900 CST and I am ecstatic about it! My foray into home brewing began mid-2011 when I obtained my general class ham license (I took Technician and General at the same time taking advice from my late grandfather). The first radio I ever purchased was the Pixie II kit and boy was that frustrating. I meticulously assembled the kit and worked very hard to stuff the transceiver, volume control, options to use the on-board key or a straight key, and maybe an on-board speaker or phones.  But, to my chagrin, I was treated to the sweet wafting smell of the magic smoke long before ever getting on the air. I eventually did get on the air with my aforementioned grandfather's VHF/UHF HT and until recently, this has been the extent of my Ham career.

 

  But on the advent of my starting an MA in applied linguistics at a school in Dallas (hour and a half from home in Waco) and the rekindling of my electronics knack occurring near- simultaneously with my discovery of the SolderSmoke Podcast, I decided to give it another go. First, I got the old pixie kit to oscillate and then ripped it apart for parts to another project (non-radio). Then I procured a second Pixie kit from ebay and built that. It oscillated right away! Still no contacts; my CW is... improving.

 

  All this to say that I still had an itch that wanted scratching Enter: The Color Burst Liberation Army! Not only could I truly build something from scratch, I could follow my true calling and de oppresso liber some crystal. So I pulled some 30 (or so) gauge magnet wire from an old CRT. I had wound and rewound my coil three times (and unfortunately, the third one looks the worst) for 80m then 20m (far fewer turns) and back to 80m with N'JOO (No Joy of Oscillation) in any configuration. I am using a polyvaricon pulled form an old AM/FM transistor radio, the Mitsumi PVC-2FX which has 82 pF, 140 pF,  20 and  40 pF sections which I have wired in parallel giving me ~0-282 pF of range? And finally, I was using a MPS A42 NPN transistor. I had to run some resistors in parallel and some caps in series to get the right values, but I eventually got it all together and looking pretty smart on a 1" x 1.5" piece of perf board. Alas! Nothing!

 

  I was poking around at the circuit and realized that when I keyed the transmitter, the coil would get really hot right at the tap. I still don't know why that was, but I figured it was a good sign as it meant something was happening. I also was getting plenty of pops and clicks on the receiver. Anyway, to make a short story long, I decided that the dark mark under the transistor was a bad sign, found an NTE 123 and plugged it in instead. And oh what a wonderful day to hear the first warblings of my very first all scratch built transmitter hitting the airwaves! And here is the video: https://youtu.be/yq2M1ryMkII

  

  Probably more than you wanted to hear, but there it is. I do plan to build an SSB transceiver someday (hoping sooner than later). I feel you and Pete and your podcast have really set me out on the right foot! I hope to HB2HB with you soon!

  Sincerely,

    Eric KD0OXY

Psst... I know a guy with some caps.... Variable caps... Real beauties.... But only for Mighty Mites.

Feast your eyes my friends.   That is 400 micro-microfarads of variable capacitance.  (400 picofarads for you sophisticated young folks.)   A benefactor interested in expanding the ranks of the Color-Burst Liberation Army has stepped forward to make us an offer that is hard to resist:  He will send ELIGIBLE recipients one each of these fine electronic components for the cost of postage (approximately 6 bucks in the USA). 

He has specified that ELIGIBILITY is limited to those who need this part to build or complete a Michigan Mighty Mite.   And I have been appointed "Grand Poobah and Chief Arbiter of Capacitor Eligibility." 

So here is the deal:  Send me an e-mail telling me about your planned or stalled Michigan Mighty Mite project.  Include some information about your personal "Knack Story"  -- tell us why you share in this strange compulsion to build a largely useless 250 mW 3.579 MHz oscillator.   If I find your plans believable and your Knack Story compelling,  I will recommend you for a capacitor.  Purely aspirational MMM projects and obviously fabricated Knack Stories will not make the cut.

Supplies are limited, so act now! 

Stuart AC9LZ's Mighty Mite

FB Stuart!  Great work.  Pete is sending you info on a Low Pass filter that will clean up that harmonic-rich signal. 

Words of Wisdom for Homebrewers -- From Dave Metz, WA0AUQ

When you are done, be proud of what you have accomplished! Use it on the air and show it off to your friends an amaze them. Then clean the bench and start dreaming about your next project. 

David Metz, WA0AUQ

http://www.fpqrp.org/homebrew.html

Summary:

• Decide if its important to do
• Study the prior work of others
• Make a preliminary simple design, document everything you do!
• Round up your parts
• Build in modules! Make one module at a time work.
• Don't get discourage, ask questions, finish what you start

http://www.fpqrp.org/homebrew.html

There is a lot of tribal knowledge and homebrew wisdom in this link.  I tried to find a picture of OM Dave, but he has kept a low profile on the www.  The best I could come up with is a symbol of the club that he has been associated with.  Thanks Dave!

Here is the full document:
http://www.fpqrp.org/homebrew.html

Brazilian Minimalism: The Curruira Transmitter

Miguel PY2OHH is the Wizard of Sao Paulo. This morning I was looking at his wonderful web site and came across this little rig.  It seems a bit simpler than our beloved Michigan Mighty Mite.  And the folks down in Brazil had several of these on the air and made contacts with them.  FB.  Miguel hints they may turn this rig into a transceiver. 

Here is the Curruira:

http://py2ohh.w2c.com.br/trx/curruira/curruira.htm

 

 

The rig is named for this little bird: 

 

 

Gregory Charvat HAS THE KNACK

Gregory Charvat N8ZRY

Yesterday I was talking to Allen W5SQK on 17.  He mentioned that he been working in his shop. You don't hear that too often these days, so naturally I asked what he was working on.  Turns out that OM Allen is building a coffee can radar!   He is enrolled in the MIT Lincoln Lab's Open Courseware Project (which looks very cool).  We had a great QSO, sharing tales of woe about the release of magic smoke from (dis)integrated circuits.  These are the things that pull us together my friends!

 

On the MIT page the name of a faculty member caught my eye: Dr. Gregory Charvat N8ZRY. Greg's rigs have been discussed on this blog at least twice, but it wasn't until today that I became aware of his many other interesting technical activities.  

 

Videos: 

https://www.youtube.com/user/charvatg

 

Bio:
http://glcharvat.com/Dr._Gregory_L._Charvat_Projects/About.html

 

Greg's KNACK STORY:

http://glcharvat.com/website%20pdfs/Charvat_Interview_AEXmag_Oct2013.pdf