Re: [time-nuts] A question from a newbie

Daniel, There's simple C code at http://leapsecond.com/tools/adev_lib.c that does ADEV / MDEV / TDEV / HDEV. A sample ADEV program using that code is: http://leapsecond.com/tools/adev1.htm There are Python versions on the web if you're into Python and its ecosystem. If you want a QBASIC version

[time-nuts] A question from a newbie

I was directed to this group when I asked this question of another group. However, after reading some of the emails I am a real novice when it comes to this stuff. I worked with cesium and rubidium oscillators as Primary Reference clocks in the telecommunication industry. When I was there I wrote

Re: [time-nuts] Datum PRS-50 ionizer voltage supply

AFAIK, the Cesium unit in the PRS-50 is a 5045A module. You mentioned a '4201A module' so this info might not apply. A couple of years ago, I helped a guy on eevblog fix a Datum 4040A which used the same 5045A module as my 4065A Cesium. It turned out that most of the capacitors in his 5045A

Re: [time-nuts] Fw: Helium and MEMS oscillators don;t mix well

This one definitely sounds more like the large induced voltages you get when the magnetic fields are ramped. Could be the same with the earlier report but that does have a few more features that are plausibly helium - the recovery of the devices particularly. On Thu, Nov 1, 2018 at 9:10 PM David W

Re: [time-nuts] Helium and MEMS oscillators don;t mix well

In message , Wayne Holder writes: >The curious thing to me is that some iPhones are said not to recover from >exposure to helium but, as an essentially mechanical device, I can think of >no reason that the SiT1532 would not recover from exposure to helium after >the gas had migrated out

Re: [time-nuts] Helium and MEMS oscillators don;t mix well

In message <04055a33-5f2b-8aff-f9b0-526c9478d...@earthlink.net>, jimlux writes: >> To get to relevant He levels via the Radon route, we are talking >> deep unventilated mineshaft kind of concentrations... >> >> Hydrogen is a lot more plausible in my view. > >Yeah, but in concentrations t

Re: [time-nuts] Helium and MEMS oscillators don;t mix well

Hi As much fun as this is, once it moves over to wireless charging as the likely issue ….. that’s getting pretty far from TimeNuts main focus….. Bob > On Nov 1, 2018, at 5:08 PM, David Witten wrote: > > Ok, one last try: > > From AuntMinnie.com, free but subscrip[tion-based newslettter for c

[time-nuts] Fw: Helium and MEMS oscillators don;t mix well

Ok, one last try: >From AuntMinnie.com, free but subscrip[tion-based newslettter for clinical radiologists and related staff: November 1, 2018 -- A second imaging facility is reporting problems with Apple devices that appear to be related to the operation of the center's MRI scanner. Nearly 10 l

Re: [time-nuts] Datum PRS-50 ionizer voltage supply

Dirk Kind of a good and bad thing. Shame it doesn't work, oh boy now you get to dig in. Nothing to lose so the fun begins. I am of the belief ionizers are low ohms. Maybe not that low but low. If its actually shorted somehow to the case then as Bob suggests you might float it with an independent su

[time-nuts] 2nd MRI center reports problems with Apple devices

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Re: [time-nuts] Datum PRS-50 ionizer voltage supply

Hi Just as a guess, it would be rare for a “heated wire” type of thing to have much over a 10:1 ratio between hot and cold. Most have ratios that are less. (think of a light bulb …) If you suspect the ionizer, I’d suggest working out just what it’s resistance is. If it’s down below 0.1 ohms

[time-nuts] Datum PRS-50 ionizer voltage supply

Hi, I acquired a PRS-50 Caesium beam frequency standard in more-or-less working order back in 2011. The manufacture date was February 2001, so the tube was probably exhausted by this stage, but it did still achieve lock so may have been in storage for some time rather than run for the whole of its

Re: [time-nuts] Helium and MEMS oscillators don;t mix well

Hi If you take an IC package up to fairly high pressure for a few hours (and it’s defective) you can pretty well fill it with helium and have it well above 1 ATM internal pressure. It will then leak out (maybe over a few years) until it gets back down to one atmosphere internally. In some r

Re: [time-nuts] Helium and MEMS oscillators don;t mix well

The oscillator mentioned in the article is a SiT1532 made by SiTime . It's sold in a chip scale package that's only 1.5mm x .9mm, which means it'a no much more than a chip of silicon with some solder balls attached. The data sheet indicates there is a "polymer" coating on the back

Re: [time-nuts] Helium and MEMS oscillators don;t mix well

Hi Now, getting back to the original issue. MEMS oscillators of some types have really tiny structures in them. They mount them as close to being in “free space” as they can. The idea is no different than a crystal. A properly shape lump running in free space has higher Q. Higher Q is normally

Re: [time-nuts] Helium and MEMS oscillators don;t mix well

Please pardon my usual incompetence posting to mailing lists... 2nd MRI center reports problems with Apple devices Aunt Minnie is a newsletter/site targeting clinical radiologists and technical staff. Dave

[time-nuts] Fwd: Delivery Status Notification (Failure)

2nd MRI center reports problems with Apple devices Aunt Minnie is a newsletter/site targeting clinical radiologists and technical staff. Dave ___ time-nuts mailing list -- tim

Re: [time-nuts] Helium and MEMS oscillators don;t mix well

Hi A mil standard leak test works like this: First you run a bubble leak, generally in something like hot synthetic oil. If the leak is too big, you will not catch it with a helium test. Next you put the parts in a pressure vessel and pressurize it with helium (or possibly a gas mix). How hi

Re: [time-nuts] Helium and MEMS oscillators don;t mix well

kb...@n1k.org said: > Helium leak testing is a *very* common thing in the oscillator industry. I’d > bet it also is done in the MEMS oscillator business as well. How does that test work? It seems obvious how to test stuff that is designed to hold Helium - put the Helium in and sniff the surr

Re: [time-nuts] Helium and MEMS oscillators don;t mix well

Hi Helium leak testing is a *very* common thing in the oscillator industry. I’d bet it also is done in the MEMS oscillator business as well. A normal oscillator can fail leak testing. I’ve never seen one that stoped working as a result of the test. Bob > On Nov 1, 2018, at 12:14 PM, jimlux

Re: [time-nuts] Helium and MEMS oscillators don;t mix well

On 11/1/18 8:52 AM, Poul-Henning Kamp wrote: In message , Bob kb8tq writes: A lot of Radon and *really* poor ventilation…. Yup. But a LOT of Radon is not without interesting "side-effects", such as much easier ionization due to the alpha radiation. To get to relevant He levels via

Re: [time-nuts] Helium and MEMS oscillators don;t mix well

On 11/1/18 8:47 AM, Bob kb8tq wrote: Hi A lot of Radon and *really* poor ventilation…. There are a lot of ways for He to show up. In normal use, issue is hanging on to it. It tends to run away from its source very quickly. Maintaining a measurable concentration in something like a normal room

Re: [time-nuts] Helium and MEMS oscillators don;t mix well

In message , Bob kb8tq writes: > A lot of Radon and *really* poor ventilation…. Yup. But a LOT of Radon is not without interesting "side-effects", such as much easier ionization due to the alpha radiation. To get to relevant He levels via the Radon route, we are talking deep unventila

Re: [time-nuts] Helium and MEMS oscillators don;t mix well

Hi A lot of Radon and *really* poor ventilation…. There are a lot of ways for He to show up. In normal use, issue is hanging on to it. It tends to run away from its source very quickly. Maintaining a measurable concentration in something like a normal room …. not very easy at all. Bob > O

Re: [time-nuts] Question about the PLL of Trimble Thunderbold

Hi Tom, On 10/31/18 10:45 PM, Tom Van Baak wrote: >> I have in mind a project which consists in synchronizing two or more stable >> clocks (OCXO) disciplined by GPS. >> >> However, would be great to have the option to disable the GPS on both sides >> at a given time and to synchronize them in a Ma

Re: [time-nuts] Helium and MEMS oscillators don;t mix well

In message , "Richard (Rick ) Karlquist" writes: >According to Jack, radon emits alpha particles, AKA helium nuclei. >These capture stray electrons and become helium atoms. So the >presence of helium is a marker for radon. The fact that the half >life is a few days supports this hypothe