Hello Gill Doing reliability calculations to MIL 217 was very instructive many years ago and it taught me that operating well under the limits extended MTBF a lot. Some military customers instructed that specs were 60% or more degraded to achieve longer service life. What was your experience of that? It amazes me that amateur psus last so long! Then, again, they are rarely continuously operated 24/7. 73 David G3UNA/G6CP
> On 16 April 2020 at 15:19 Gill via Elecraft <elecraft@mailman.qth.net> wrote: > > > As Harlan pointed out - I was an engineer for the FAA until retirement - > We changed electrolytics as part of normal PM's on critical systems > usually every 5 years or so. CDE (Cornell Dubilier) indicates expected > life (MTBF) of devices operated within rated voltage & temp specs to be > about 80-100 thousand hours. Most failures occur quickly around the end > of that period. For 24/7 operated systems, that translates to around > 8-10 years before rapid EOL failures begin to occur. Electrolytics can > be thought of like incandescent lamps - they have a finite useful life > and the fail quickly around the end of that time. ESR (Equivalent Series > (AC) resistance) increases which reflects in higher ripple currents in > power supplies are a main culprit. Check out: > https://www.cde.com/resources/technical-papers/reliability.pdf > 73 Gill W4RYW > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to d.cut...@ntlworld.com ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
