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MFJ-868 SWR/Wattmeter
On 9/8/2011 1:30 PM, Jim Lux wrote:
And, you can take ESD hits that degrade, but don't destroy, the part. I've got some LNAs in my desk drawer that appear to work just fine, except the NF is a bit higher than it used to be. How do you know it was ESD that caused the degradation? |
#2
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MFJ-868 SWR/Wattmeter
On Thu, 08 Sep 2011 14:12:20 -0500, John S
wrote: On 9/8/2011 1:30 PM, Jim Lux wrote: And, you can take ESD hits that degrade, but don't destroy, the part. I've got some LNAs in my desk drawer that appear to work just fine, except the NF is a bit higher than it used to be. How do you know it was ESD that caused the degradation? "How often have I said to you that when you have eliminated the impossible, whatever remains, however improbable, must be the truth?" Sir Arthur Conan Doyle, The Sign of the Four, chap. 6. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#3
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MFJ-868 SWR/Wattmeter
On 9/8/2011 12:27 PM, Jeff Liebermann wrote:
On Thu, 08 Sep 2011 14:12:20 -0500, John wrote: On 9/8/2011 1:30 PM, Jim Lux wrote: And, you can take ESD hits that degrade, but don't destroy, the part. I've got some LNAs in my desk drawer that appear to work just fine, except the NF is a bit higher than it used to be. How do you know it was ESD that caused the degradation? Oh.. I don't know on the ones in the drawer that's what did it (because they still work, after a fashion), but on some other ones where we did failure analysis, you can see the damage on the SEM photos. We've got whole books full of pictures of this kind of thing. That's partly why industry has gone from marking just sensitive things to marking everything ESD, including nuts and bolts. It's just too easy to get damage without any obvious signs. Consistent practices reduce the possibility, which increases yield. The concern is the "weakening" or "partial damage without causing outright failure" kind of scenario, especially in a hi-rel situation. There's a lot of interest in figuring out a way to test for this kind of thing, as you can imagine. And there's even evidence that the damage can heal (anneal), much like radiation damage (both are basically deposition of energy in the wrong place and the wrong time, right), but the mechanics of the process is poorly understood. http://www.fainstruments.com/PDF/eosesd93.pdf http://eed.gsfc.nasa.gov/562/ESD_Failures.htm http://trs-new.jpl.nasa.gov/dspace/b.../1/00-1338.pdf |
#4
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MFJ-868 SWR/Wattmeter
On 9/8/2011 4:18 PM, Jim Lux wrote:
On 9/8/2011 12:27 PM, Jeff Liebermann wrote: On Thu, 08 Sep 2011 14:12:20 -0500, John wrote: On 9/8/2011 1:30 PM, Jim Lux wrote: And, you can take ESD hits that degrade, but don't destroy, the part. I've got some LNAs in my desk drawer that appear to work just fine, except the NF is a bit higher than it used to be. How do you know it was ESD that caused the degradation? Oh.. I don't know on the ones in the drawer that's what did it (because they still work, after a fashion) That's the reason I asked. Thank you. |
#5
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MFJ-868 SWR/Wattmeter
On 9/8/2011 4:12 PM, John S wrote:
On 9/8/2011 4:18 PM, Jim Lux wrote: On 9/8/2011 12:27 PM, Jeff Liebermann wrote: On Thu, 08 Sep 2011 14:12:20 -0500, John wrote: On 9/8/2011 1:30 PM, Jim Lux wrote: And, you can take ESD hits that degrade, but don't destroy, the part. I've got some LNAs in my desk drawer that appear to work just fine, except the NF is a bit higher than it used to be. How do you know it was ESD that caused the degradation? Oh.. I don't know on the ones in the drawer that's what did it (because they still work, after a fashion) That's the reason I asked. Thank you. Yeah.. the guy or gal who figures out a good non-destructive, no disassembly required way to detect latent ESD damage is going to be a hero for those of us building one-off high-rel gear. There have been some partial solutions for specific parts, but no generalized way, yet. |
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