The Manassas Hamfest

Elisa heroically accompanied me to the Manassas Hamfest on Sunday.  We had fun.  I thought they had a good turnout of vendors and tailgaters, and it seemed like the sellers of real ham stuff were winning the battle against the encroaching computer people.  I saw many interesting old boatanchor radios, including two R-390A receivers, one HT-37, an HW-101 and several other Heathkits.

As for NEW technology, the fellows from the NOVA LABS maker space had a very interesting table, and their web site has a very kind acknowledgement that hams were "the original hackers, who organized build groups and hack labs similar to modern day makerspaces—back before people called themselves “Makers” and long before it was “cool.”  They had a 3-D printer that was doing its thing in a very impressive manner.  They also had some quadro- and octo-copters built by a group called DC Area Drone User Group.   Very cool.  Want one.

Inspired by Nick Kennedy, I have included in this post a picture of my purchases from the hamfest.  As you can see, I controlled myself.  But I couldn't resist the humungous flashlight!  I got a bunch of .1 caps (should have bought more!).  Got a Bud-box (maybe for an Arduino DDS project?)  The little circuit board with the IF cans is interesting.  I bought it (1 dollar!) for the 365 pf variable  cap, but I later realized that it is probably a complete All-American Five receiver on a single board.  I'm not crazy about tubes on PC boards, but this one may have some possibilities.  The roll of tape is supposedly coax sealer.  I also got a little 35 mm slide viewer, and a 12 volt wall wart.

I wore the "Real Radios Glow in the Dark" T-shirt that Elisa got me (on the recommendation of Rogier).  I got more positive comments on that shirt than on any other piece of clothing I've ever owned!

And we saw our first Cicadas of this 17 year cycle. 

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

OOPS! Why the AD9850 DDS Boards are So Inexpensive

N3ZI has a very plausible explanation for the low price (about 9 bucks!):

My guess is that this is a liquidation due to a design build error, since they are being sold for a price of about 1/2 the price of the DDS chip alone. The modules are assembled and tested. The design error I noticed is that the wrong output filter is used. These boards use the 9850 running at 125MHz. A 125MHz DDS should have a 50MHz LPF, but it seems that these modules have the 75MHz LPF the chip maker recommends for the AD9851 running at 180MHz. My guess is, someone just copied the wrong filter from the wrong data sheet, and it wasn't caught until they went into production.
But for amateur radio applications they work fine up to about 40MHz. You can push them to 50MHz by adding a correcting filter, which is included in my controller PCB, but the output level is low in the 40-50MHz range.

N3ZI continues to offer some really interesting microcontroller products.  He has a controller board that allows you to simultaneously control TWO AD9850 boards.  This might be exactly what we need when we have a separate receiver and transmitter with different intermediate frequencies: Set up one board with the VFO freq for the receiver and the other for the transmitter with the resulting operating freq displayed on the LCD.  Viola! No more "Spot" or "net" and zero-beat by ear! (But I may be one of the last people on the planet still doing this!)   

N3ZI's site:  http://www.pongrance.com/

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

R-390A and Homebrew TX put in Transceive Mode (VIDEO)

N8ZRY has a very nice video on his recent adventures with the legendary R-390A receiver (want one!) and his homebrew 20 meter SSB transmitter.  He manages to essentially put the receiver and transmitter into "transceiver" mode.  Very nice.  I wonder if he had previously used the old standard "spot" or "net" "zero beat by ear" method?  This video has me thinking about ways to bring my many separate receivers and transmitters closer together. The problem is that they all use different IF frequencies (the crystal filters are at different frequencies).  But using my Arduino-based DDS VFO, I guess it wouldn't be too difficult to program the thing to generate one VFO freq for transmit, and a different VFO freq on receive, in effect putting the transmitter and receiver on the same frequency. 

Both the R-390A and the homebrew transmitter look great.   Thanks Greg!


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

Dutch Knack During WWII

 

 

There is a very nice article on the MAKE blog this morning: 
http://blog.makezine.com/2013/06/06/an-early-maker-story-from-holland/
 
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

Quote of the Day: On Tinkering

Finally, some justification for my "build first, design later" method:

"Contraptions, machines, wildly mismatched objects working in harmony -- this is the stuff of tinkering.  Tinkering is, at its most basic, a process that marries play and inquiry."

from www.exploratorium.edu/tinkering   Quoted in Massimo Banzi's book "Getting Started with Arduino."

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

Alan Yates, VK2ZAY, is back in the knack!

I was getting kind of worried.  I hadn't seen any new articles on Alan's excellent web site.  But on my last visit I learned that he has moved to Seattle and is going to Maker Faires:  http://www.vk2zay.net/article/268

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

Save 20% on Knack Books

Codeword: GLOW.   Very appropriate for Grayson's Thermatron book: 



http://www.lulu.com/shop/grayson-evans/hollow-state-design/paperback/product-20987562.html


And also for mine (tubes, QRP fireflies and all that):



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