On Mon, Jul 1, 2019 at 6:35 AM Bob kb8tq <kb...@n1k.org> wrote: > > Hi > > There are a lot of posts back in the archives about various things on Cs > standards. > > Beam current is probably the best way to see “how much is left”. On a high > performance > tube, it drops pretty fast at end of life. That makes is a bit of an iffy > measure there. If the unit has been > in storage for a while, it may take a week to pump down to even get working > ….. (and see the beam > current). > > Most Cs standards you see for sale on eBay are listed as “parts only”. They > may work, they may not work. > The price is likely to be in the $1,000 to $3,000 range delivered. As soon as > one gets listed as “working” the > price goes through the roof ( like 5x to 10X). Since there is no test for > “how much is left”, I’m not sure that is > a good price to pay. > > So your choice is to pay a silly price on one that may last a couple months ( > or may go on for years) or > to pay a low price for who knows what. On the one with the silly price, you > might be able to get some info. > On the reasonable price units, the seller is probably not going to do much. > > From time to time, they show up here on the list. In that case the seller > likely knows a bit more about > the unit than the typical eBay listing. Even so, there are no guarantees. A > unit that was working very > well on the seller’s bench may run out of steam a few months later.
Speaking of.... I've been meaning to clear out my workshop for a long time, and am finally starting to do so. I have two "Datum PRS-50 Cesium Beam Primary Reference Source" - one of them comes up and locks happily, the other logs an error which decodes to " "ionizer supply - voltage (V) across the ionizer filament" being too low (~0.5V when it should be ~1.6V). I *think* I saw some mention of failing capacitors being a common cause of this - I've been meaning to take readings from the good one, and comparing to the bad to try hunt down the issue, but I haven't had the time. I also have a FTS 4060 Cesium Time and Frequency Standard which works perfectly. These are all just sitting in my workshop, and I'm feeling guilty that they are not being loved -- and so I'm going to be selling them. They are bulky / heavy (and I'm lazy!), and so I'm going to be optimizing for someone who A: has a good use for them and B: can come pick them up (I'm in Northern VA, near Washington Dulles (IAD) airport) instead of maximizing the price... which I haven't even begun trying to figure out yet.. A random, unsorted pile of pictures is here: https://photos.kumari.net/Projects/AtomicClocks/ I'm currently traveling, but hope to get things better organized in early August... W > > Bob > > > On Jun 30, 2019, at 6:20 PM, Glen English VK1XX > > <glenl...@pacificmedia.com.au> wrote: > > > > Bob, are there any URLs you can point to, or provide advice on, if > > inspecting a Cesium for sale, is there an hour counter, or other metrics > > that can be measured in the tube department ? (I am familiar with TWTs, > > Klystrons etc so the HV doesnt bother me) in order to ascertain the level > > of life left ? > > > > that is, apart from turning it on and waiting a while and measuring ADEV > > for a week.... on the sellers premises. > > > > glen > > > > > > On 1/07/2019 7:09 AM, Bob kb8tq wrote: > >> Hi > >> > >> Based on several replacements on a “high performance” 5071 …. 6 to 7 years > >> of 24/7/365 seems to > >> be about the point things start to get flakey. Maybe not dead, but crazy > >> enough that it lets you know > >> it needs a new tube ( = ADEV is not even close to what it should be ..). > >> > >> Cost several years back for the swap out was right at $40K. The process > >> included hazmat shipping > >> silly nonsense. That part delayed the process by almost 2 months. > >> > >> Bob > >> > > > > > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. -- I don't think the execution is relevant when it was obviously a bad idea in the first place. This is like putting rabid weasels in your pants, and later expressing regret at having chosen those particular rabid weasels and that pair of pants. ---maf _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.