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20150124 - Direct Digital Synthesis

posted Jan 23, 2015, 4:12 PM by Onno Benschop   [ updated Jun 8, 2015, 4:19 AM ]
Denis VK6FADF shares this:
As you’ll probably know there are a range of direct digital synthesis chips on the market from Analog Devices (AD9850, 9851, …) Silicon Labs (Si570, Si5351, …) and other manufacturers.   These are typically programmed from an Arduino, Raspberry Pi, etc or even from a DIP switch and glue logic.   They output one or more channels of sinewave / squarewave with a range from several Hz to the 100MHz region.   eBay has a few and I’ve bought two of the AD9850 class but what you may be interested in is something I discovered by accident a few days ago.
There is a crowd-funding collective called Indiegogo and they run “campaigns” where someone with a bright idea gets money from interested “investors” who sign up to buy the new product.   One such here is the Si5351A Breakout Board produced by an American Ham, Jason Milldrum.   Jason sells these in various configurations including with an oven controlled crystal frequency reference and SMA connectors for US$22   WARNING – is in kit form and surface mount soldering skills are mandatory!
It could be the basis of a very tasty vector network analyser, amongst other things – personal beacon comes immediately to mind.   Okay, beyond test equipment a standard or advanced license would be called for but there is a growing group of these within F-Troop J
If interested Google for Indiegogo and search for Si5351A breakout Board
Now the SMD skills part!   To the present I have done very little in the SMD line.   One of the VHF Group members uses very successfully a hot air gun by Bosch which has an LCD temperature readout.   Another thought is to use a cheap hot plate and a simple mechanism for manipulating the board(s) such as shown here… http://vk5hse.blogspot.com.au/2013/03/50-ohm-smd-dummy-load-prototype.html   I have seen another of his blogs talking specifically about the hotplate-based SMD reflow solution.  It will be on that site somewhere….   I’m thinking to make such a jig and make it available for loan if anyone is interested.   But a few other irons in the fire at present so by the time the breakout board arrives, who knows!   I’ll also get a kit or two of SMD soldering practice boards from eBay.