Re: [time-nuts] UCCM GPSDO

Well, that actually helped a little. I dug a little further into the system documentation, and while there is only a smattering of information on the UCCM itself, I was able to find that the alarm parameters for them dictate a 5.2-5.8v supply range, so THAT finally definitively answers one of

Re: [time-nuts] UCCM GPSDO

Almost every PC Board made in the last few decades is UL 94V-0. John K1AE -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Van Horn, David Sent: Monday, December 05, 2016 3:35 PM To: Discussion of precise time and frequency measurement Subject: Re:

Re: [time-nuts] UCCM GPSDO

Yes. -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Glen Hoag Sent: Monday, December 5, 2016 12:14 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] UCCM GPSDO 94V-0 is a UL flame retardancy test, if I recall

[time-nuts] NIST in the news: new stability record

This will be showing up in the popular press. Zero dead time Ytterbium lattice clock, PR release: "NIST Debuts Dual Atomic Clock - and a New Stability Record" https://www.nist.gov/news-events/news/2016/11/nist-debuts-dual-atomic-clock-and-new-stability-record Nature article (paywall,

Re: [time-nuts] UCCM GPSDO

94V-0 is a UL flame retardancy test, if I recall correctly. Sent from my iPhone > On Dec 5, 2016, at 12:34, Tim Shoppa wrote: > > I was trying to guess what acronym (or backronym) UCCM might stand for. > Then I did an E-bay search and found all the PC boards with "94V-0" in

Re: [time-nuts] UCCM GPSDO

I was trying to guess what acronym (or backronym) UCCM might stand for. Then I did an E-bay search and found all the PC boards with "94V-0" in their part numbers for sale E-bay. Ha! Literally thousands of hits. Tim N3QE On Mon, Dec 5, 2016 at 7:42 AM, Bob Camp wrote: > Hi > >

Re: [time-nuts] Switching regulator replacement for 7805

FWIW, you can snub the switch node to dampen parasitic ringing in exchange of a loss in efficiency of a couple percent. I'm pretty sure I have seen this outlined in a few app notes. On Mon, Dec 5, 2016 at 1:22 PM, jimlux wrote: > On 12/5/16 9:13 AM, Dan Kemppainen wrote: >

Re: [time-nuts] Switching regulator replacement for 7805

On 12/5/16 9:13 AM, Dan Kemppainen wrote: Depending on the application, another possible application is to sync up the DC/DC converter to the "main" clock source. This makes the switching noise then coherent to the system, which either makes it average out completely, or possible to filter it

Re: [time-nuts] UCCM GPSDO

The UCCM modules came from Samsung WiMAX radio systems. It looks like they OEM'd the boards from both Trimble and Symmetricom. "UCCM = Universal Core Clock Module" UCCM-P = "Universal Core Clock Module - Plus". I managed to find a system description document that mentions it two or three

Re: [time-nuts] Switching regulator replacement for 7805

Depending on the application, another possible application is to sync up the DC/DC converter to the "main" clock source. This makes the switching noise then coherent to the system, which either makes it average out completely, or possible to filter it out in the digital domain using a deep

Re: [time-nuts] Switching regulator replacement for 7805

On 12/5/2016 12:00 PM, time-nuts-requ...@febo.com wrote: This is exactly the PWM to PFM mode switch I described earlier. The 850mA are probably high enough that the DC/DC converter works in PWM mode, thus switching with a constant frequency, even if the load changes. On the other hand 200mA

Re: [time-nuts] Switching regulator replacement for 7805

In my experience the term ferrite bead is used more loosely today. Most "beads" that I've designed with were 100% machine placeable surface mount parts from smallish 0402 chips on up to 10A rated honkers. Admittedly any tubular "bead on wire" is not machine placeable in a surface mount oriented

Re: [time-nuts] Switching regulator replacement for 7805

Not impressed with the PCB layout, could have been much better. Input cap is too far from regulator, connected to ground via longish (inductive) skinny trace. Input might benefit from simple PI filter to reduce input ripple current. Output caps should each have their own via, maybe even two

Re: [time-nuts] Switching regulator replacement for 7805

Hi The BLM18 gives you 300 ohms at zero current. It’s impedance at zero current per the data sheet. If you look at other parts of similar size, the impedance drops to nearly zero at the “rated current”. Great if you have a signal lead and no current. Not so great if you have an OCXO that is

Re: [time-nuts] Switching regulator replacement for 7805

Attila - I certainly do not differentiate between "ferrite bead" and "single turn toroidal choke". I think the SMT inductor manufacturers think of them in the same bucket too. what I think of as a "ferrite core for winding a multi turn inductor on", is invariably listed as a "ferrite bead" in

Re: [time-nuts] UCCM GPSDO

Hi I’d bet it’s an inventory label put on by their customer. If so a good bet would be something like China Unicom. Bob > On Dec 4, 2016, at 5:50 PM, Larry McDavid wrote: > > Does anyone know the origin of the "UCCM" designation for the Trimble GPSDO > boards recently

Re: [time-nuts] Switching regulator replacement for 7805

On Sun, 4 Dec 2016 17:07:53 -0800 jimlux wrote: > > Wouldn't it be better to use a ferrite bead instead, for this application? > > The much lower series capacitance and thus higher self-resonance frequency > > should help damping the spurs. > > > sure, if you can get enough