Hi Indeed back at Motorola, a lot of that stuff got transferred into the engineering stock room after a while. Just how that worked out budget wise …. one wonders ….
Bob > On Dec 24, 2018, at 11:53 AM, jimlux <[email protected]> wrote: > > On 12/24/18 5:36 AM, Bob kb8tq wrote: >> Hi >> The gotcha is - if you have a very unique part in a device and it goes away, >> how >> many years of stock do you buy on the “last chance” order? >> In the case of the 5071, I’d bet a pretty good brand of six pack that nobody >> on the >> planet would have guessed 20 years ago that it still would be in production >> today. > > EOL buys for a product line are plausible. But if you're building one-off > (or limited quantity)- maybe not. At work (JPL) there's a whole aspect to > sparing that's kind of subtle - you get funded per mission, and it has a cost > cap at the proposal stage. > > Buying extra parts "just because" cuts into your budget - what do you give up > because you bought extra parts, maybe some engineering hours? or test time? > - it's easy to say "oh what's a few parts here and there", but pretty soon, > it's getting to be a big part of your budget. > > So you buy enough parts to build what you're going to launch, plus enough > maybe for an EM or breadboard, and then a few spares in case there's some > assembly errors, or you need to scrap a board. If the problem happens early > enough, you've got time to burn some reserves and order more. > > The other problem in the space business is that there is a lot of desire to > re-use known good designs. That part may have been a long way from EOL when > it was first used, but now, 5-10 years later, maybe it's EOL, and there's no > obvious "drop in" replacement. Do you redesign, or do you buy the last > remaining stock and hope for the best? > > This tends to be a cascading issue - mission A designs and uses part X, and > has spares. Smaller Mission B uses the spares to build their widget using > the Mission A design. They buy a few spares too. Smaller Mission C does the > same thing. Now we're 10 years in, in some cases still using spare parts > bought by original Mission A. > > I am still using spare connectors and such from Cassini (launched in 1997) in > things like breadboards at work. > > > >>> On Dec 24, 2018, at 1:59 AM, Hal Murray <[email protected]> wrote: >>> >>> >>> [email protected] said: >>>> and the "market lifetime" of parts today is much shorter. There are lots >>>> of >>>> parts from Hittite that were essentially "run on this line only", and when >>>> they moved geometries, they're never to be seen again. >>> >>> Most vendors make a lot of noise before they pull the plug on a part. The >>> usual deal is that they fill all orders placed by a specified date - >>> lifetime >>> buy. Distributors typically send a note to anybody who has purchased them, >>> or >>> maybe only purchased significant quantities. >>> >>> If a part isn't expensive, you can afford to buy extras beyond what you >>> expect >>> to need to cover some what-ifs. That probably doesn't cover something like >>> the 5071 being in production for 30 years. But it could give you a few >>> years >>> warning - maybe enough time to find a substitute and/or redesign that >>> section. >>> > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
