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Wednesday, May 7, 2014

Parts Cost for BITX in India: $5 US (that's buying all the parts!)


I knew that in India you could build a BITX for a few bucks, but I thought that this cost estimate assumed a fairly well-stocked junk box.   Not true!  This morning an e-mail from Farhan points out that even if an Indian ham has to BUY all the parts, he can get all of them for the equivalent of 5 dollars U.S.:

"Less than half a cent per resistor, less than a cent per capacitor, two cents per npn transistor and 50 cents for the IRF510. We use 'tv baluns' and tap washers for coils."

And, from the original BITX design page:

 "The purpose is to address the need among Indian hams in particular for an SSB rig that is easily and cheaply built. My original aim was to keep the price under Rs. 1000. The current design brings the cost to well under Rs.300 (less than 7 dollars)."

Now, when you are talking to someone using a new $10,000 Yaesu/Icom/Kenwood rig, it might be a bit unkind to mention that your rig can be had for $5. 


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Saturday, May 3, 2014

The Guy who Invented the LED

I'm a big fan of Ira Flatow's "Science Friday" radio program (recommended!)
This week, while digging through the archives, I found this gem:

http://www.sciencefriday.com/segment/10/12/2012/fifty-years-ago-a-bright-idea.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

Friday, May 2, 2014

Bert's EMRFD Direct Conversion Receiver



Very nice Bert.  Sounds great.  I like the pill bottle coil core.  Lew McCoy used them in his designs. I do think that air core coils do provide better stability than ferrites or iron powder.   I kind of like the SW broadcast background music.  I also like the internal 9V battery.  Glad to see someone else resurrecting an old DC RX project.  


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, May 1, 2014

VFO for BITX 20/40


Here's the VFO I use in my BITX 20/40.   IF is obviously 11 MHz.   VFO normally tunes 3697-3859 kHz for 40 meters.  Switching in that 220 pf cap lowers the range to 3292-3189 kHz for 20 meters.  It workd very well.   The coil is wound on a cardboard tube from a coat hanger.  I will put this in the appropriate file on the BITX group site.    I like the 20/40 band combination:  Good DX possibilities on 20, with provisions (40!) for the low sunspot counts to come.

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, April 30, 2014

Manhattan meets Hyderabad: Pad Pattern for my BITX 20/40


A rough guide to how I laid out the isolation pads on my BITX 20/40 board.   The copper-clad board is 8 inches x 11 inches (22 cm x 28 cm).  I just cut out the pads as needed using tin shears and scrap pieces of copper clad board.  Gorrilla SuperGlue is my preferred adhesive.  I will put this in the appropriate file on the BITX 20 yahoo group site.


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, April 28, 2014