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#1
February 29th 04, 02:12 AM
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Which DDS chip?
I like to experiment with the Analog Devices DDS for a receiver.
Anyone have a favorite one with good features and least hassle? |
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#2
February 29th 04, 02:27 AM
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The 9850 seems to be pretty popular. You can plunk one down on a DDS
daughtercard from NJQRP or get one of the Far Circuits boards (although in my experience their quality is a tad spotty). The Tayloe mixer can be fed with a 9854 and that looks like a fun experiment but the 9854 only seems to be available in impossible packages. ... "SWbeginner" wrote in message ... I like to experiment with the Analog Devices DDS for a receiver. Anyone have a favorite one with good features and least hassle? |
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#3
February 29th 04, 02:27 AM
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The 9850 seems to be pretty popular. You can plunk one down on a DDS
daughtercard from NJQRP or get one of the Far Circuits boards (although in my experience their quality is a tad spotty). The Tayloe mixer can be fed with a 9854 and that looks like a fun experiment but the 9854 only seems to be available in impossible packages. ... "SWbeginner" wrote in message ... I like to experiment with the Analog Devices DDS for a receiver. Anyone have a favorite one with good features and least hassle? |
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#4
February 29th 04, 09:25 PM
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"xpyttl" wrote in message ... The 9850 seems to be pretty popular. You can plunk one down on a DDS daughtercard from NJQRP or get one of the Far Circuits boards (although in my experience their quality is a tad spotty). The Tayloe mixer can be fed with a 9854 and that looks like a fun experiment but the 9854 only seems to be available in impossible packages. The packaging is not "impossible" - it just takes some different techniques to do the soldering - read the QEX article on a DDS/PLL synthesiser in the latest issue of QEX and check out the SMT stuff on the ARRL website ... DIPs are all but gone - that is the reality, and other "through hole" parts are getting (and will continue to get more and more) scarce and expensive, as industry has gone to SMT in a BIG way because: 1) it's better (preformance, due to reduced parasitics from leads, also more reliable if done right ...) 2) it's cheaper 3) it allows things to be build smaller 4) it doesn't eat up space on all the layers of the PCB for through holes 73, Carl - wk3c |
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#5
February 29th 04, 09:25 PM
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"xpyttl" wrote in message ... The 9850 seems to be pretty popular. You can plunk one down on a DDS daughtercard from NJQRP or get one of the Far Circuits boards (although in my experience their quality is a tad spotty). The Tayloe mixer can be fed with a 9854 and that looks like a fun experiment but the 9854 only seems to be available in impossible packages. The packaging is not "impossible" - it just takes some different techniques to do the soldering - read the QEX article on a DDS/PLL synthesiser in the latest issue of QEX and check out the SMT stuff on the ARRL website ... DIPs are all but gone - that is the reality, and other "through hole" parts are getting (and will continue to get more and more) scarce and expensive, as industry has gone to SMT in a BIG way because: 1) it's better (preformance, due to reduced parasitics from leads, also more reliable if done right ...) 2) it's cheaper 3) it allows things to be build smaller 4) it doesn't eat up space on all the layers of the PCB for through holes 73, Carl - wk3c |
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#6
February 29th 04, 11:32 PM
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"Carl R. Stevenson" wrote in message
... The packaging is not "impossible" - it just takes some different techniques to do the soldering - read the QEX article on a DDS/PLL synthesiser in the latest issue of QEX I'm pretty comfortable with SOP's and can get along with a TSSOP's, although I can't say I like it. In that article, he used TQFP's which, although I haven't yet had the need, I suspect I can deal with. I use the same technique for TSSOP's that he describes in the article. But when I tried to order samples of 9854's the other day, the only choice was BGA's. I have no clue how to deal with them. Yeah, solder paste and an oven MAYBE, but without machine placement seems like a crap shoot. ... |
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#7
February 29th 04, 11:32 PM
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"Carl R. Stevenson" wrote in message
... The packaging is not "impossible" - it just takes some different techniques to do the soldering - read the QEX article on a DDS/PLL synthesiser in the latest issue of QEX I'm pretty comfortable with SOP's and can get along with a TSSOP's, although I can't say I like it. In that article, he used TQFP's which, although I haven't yet had the need, I suspect I can deal with. I use the same technique for TSSOP's that he describes in the article. But when I tried to order samples of 9854's the other day, the only choice was BGA's. I have no clue how to deal with them. Yeah, solder paste and an oven MAYBE, but without machine placement seems like a crap shoot. ... |
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#9
March 1st 04, 12:06 AM
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In article ,
says... "Carl R. Stevenson" wrote in message ... The packaging is not "impossible" - it just takes some different techniques to do the soldering - read the QEX article on a DDS/PLL synthesiser in the latest issue of QEX I'm pretty comfortable with SOP's and can get along with a TSSOP's, although I can't say I like it. In that article, he used TQFP's which, although I haven't yet had the need, I suspect I can deal with. I use the same technique for TSSOP's that he describes in the article. Actually, the 16-pin PLL chips are TSSOPs, while the AD9852/AD9854 packages I used are considered "LQFP" packages. These are a little thicker than TQFP but are otherwise pretty similar. The DDSes have the same spacing between pins as the TSSOPs (0.5 mm) but more of 'em (80). But when I tried to order samples of 9854's the other day, the only choice was BGA's. I have no clue how to deal with them. Yeah, solder paste and an oven MAYBE, but without machine placement seems like a crap shoot. That's not good news. BGAs really *are* the end of the world for homebrewing as far as I'm aware. I have not heard of any techniques for soldering them by hand. Interestingly, though, having just checked FindChips.com, Digi-Key appears to be selling both AD9852ASQs (http://www.digikey.com/scripts/DkSea...ame=AD9852ASQ- ND&Site=US) and ADF4112 PLLs (http://www.digikey.com/scripts/DkSea...sus.dll?PName? Name=ADF4112BRU-ND&Site=US). That *is* good news. I'll have to go update the article page. -- jm ------------------------------------------------------ http://www.qsl.net/ke5fx Note: My E-mail address has been altered to avoid spam ------------------------------------------------------ |
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#10
March 1st 04, 03:49 AM
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"xpyttl" wrote in message ... "Carl R. Stevenson" wrote in message ... The packaging is not "impossible" - it just takes some different techniques to do the soldering - read the QEX article on a DDS/PLL synthesiser in the latest issue of QEX I'm pretty comfortable with SOP's and can get along with a TSSOP's, although I can't say I like it. In that article, he used TQFP's which, although I haven't yet had the need, I suspect I can deal with. I use the same technique for TSSOP's that he describes in the article. But when I tried to order samples of 9854's the other day, the only choice was BGA's. I have no clue how to deal with them. Yeah, solder paste and an oven MAYBE, but without machine placement seems like a crap shoot. With BGAs you HAVE to reflow solder ... however if the prep is right, they should "self-center" (as do most SMDs) on the pads if you're close enough - it's interesting to watch manually placed SMD resistors, caps, etc. actually move an center themselves up on the pads due to surface tension effects when the solder reflows ... IF the pads are well-designed and balanced. 73, Carl - wk3c |
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