Re: [time-nuts] Alfred Loomis - an early time nut

I've just received my June Radcom which contained news of the passing of a Walter Blanchard who was involved in the development of Decca Navigator and Loran C, he also worked on a GPS forerunner navigation system called "Transit". There's an obit at www.rsgb.org/sk which may contain more detail

Re: [time-nuts] Alfred Loomis - an early time nut

t...@leapsecond.com said: > Yes, the book about Loomis by Jennet Conant is highly recommended. I thought it was a great read. There is a CSPAN author interview on youtube. Not much about time-nuttery but lots of stories about the people involved. Her grandfather was president of Harvard

Re: [time-nuts] OCXO Support Board

kb...@n1k.org said: > Probably not a big deal for a basement project. It would have stopped things > dead if we tried to run it at work. We had at least 4 layers of rules > checking that ran before the board finally went out for fab ….. Could you give a few examples of the more obscure

[time-nuts] measuring timing variation in a web conference.

A practical data source has become available for me to look at. The lab had a virtual town hall, and one of the senior managers has a pendulum clock in the background. And, there were obvious drops in the video stream, because the pendulum would "jump" (it was commented on by viewers - "That

Re: [time-nuts] Alfred Loomis - an early time nut

The Alfred Loomis story is very interesting. Thanks for bringing it up again. The PBS American Experience episode is certainly worth watching. A question for TVB (or anyone else that might know), what happened to the three Shortt clocks that he had? Also of interest would be how many still

Re: [time-nuts] f-multipliers from VHF to 10 GHz

Cesium is 9.192 GHz; use a Cs standard design as a point of departure...? Mike -Original Message- From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of Gerhard Hoffmann Sent: Thursday, May 14, 2020 20:58 To: Discussion of precise time and frequency measurement Subject:

[time-nuts] f-multipliers from VHF to 10 GHz

I have a potential project in the electron spin spectroscopy sector and I need one or two clean signal sources in the 10 GHz range. Phase noise at, say, 50 Hz offset is important, but anything below 110 dBc  does not care. That probably calls for a multiplied crystal. These Hittite PLLs from AD

Re: [time-nuts] f-multipliers from VHF to 10 GHz

Wenzel Associates (www.wenzel.com) In Austin TX can build custom rack mounted multiplied very low phase noise crystal sources. I have used their custom microwave multiplied crystal sources at my pre-retirement job (Tektronix RF Application Engineer) with a 12.5 GHz output. A few of my customers

Re: [time-nuts] OCXO Support Board

Most of the PC board manufacturers run a rules check for your board against their process capability. I have had them catch some things from time to time that the design tool missed. For commercial business, I more rules checking is always better, but for hobby and personal purposes, I think the

Re: [time-nuts] measuring timing variation in a web conference.

In message <698338c4-f4df-444e-29eb-e7e8fa3b9...@earthlink.net>, jimlux writes: >And, there were obvious drops in the >video stream, because the pendulum would "jump" (it was commented on by >viewers - "That stuttering clock was driving me crazy" ) ... or he was devious enough to have

Re: [time-nuts] OCXO Support Board

Hi Well, a full list of all the rules we ran against would run about 10 pages. I think that’s getting pretty far off topic for TimeNuts. I also, quite frankly never bothered to memorize them all. A few examples of what one *might* do: 1) “Allow” a violation. Things like courtyard overlaps

[time-nuts] FE-5680A tuning vs resonant peaks

I wonder if my FE-5680A is locking to the wrong resonance, or that I've tweaked it too far off the main one. Setup: FE-5680A Rubidium oscillator with passive support/breakout board, ostensibly regulated with an LM1084-ADJ. Trimble Thunderbolt GPSDO, feeding an HP-53131A universal counter as

Re: [time-nuts] FE-5680A tuning vs resonant peaks

Hmmm... You mention varying suply voltage by 1.5V, but from where as a starting point? It's been a while since I calibrated an FE5680A but looking back through my notes, doing it "properly" is, or was for me anyway, a non trivial exercise.I'm not familiar with the Windows software mentioned but

Re: [time-nuts] FE-5680A tuning vs resonant peaks

> Hmmm... > You mention varying suply voltage by 1.5V, but from where as a starting point? Sorry, that is a red herring.  The regulator on the support board needs enough headroom to regulate to 15V for the FE5680A.  Thus anything less than about 17V input will drag down the voltage into the unit,

Re: [time-nuts] OCXO Support Board

Thanks Mark for reminding me, spend 3 hours this morning reviewing designs to be released. Found a couple of problems. Also went back to look at the OCXO boards I released in 2018, found a problem on the board with no Amp, the SMA is not grounded. Easy to fix, but if some one wants new Gerber

Re: [time-nuts] OCXO Support Board

On 5/14/20 5:07 PM, Bob kb8tq wrote: > No, the cheap board houses don’t check for this stuff. They just build and > send it > back. If there’s a gotcha, you get it on the board. I was pleasantly surprised last week when Seeed Fusion contacted me to point out a problem where two vias were too

Re: [time-nuts] OCXO Support Board

Am 15.05.20 um 01:25 schrieb John Ackermann N8UR: On 5/14/20 5:07 PM, Bob kb8tq wrote: No, the cheap board houses don’t check for this stuff. They just build and send it back. If there’s a gotcha, you get it on the board. I was pleasantly surprised last week when Seeed Fusion contacted me

Re: [time-nuts] Teensy 4.1

It's pretty legit and can run like any other Arduino does. With 100Mbit physical Ethernet built in that's pretty big for a tiny board. It supports the precision time protocol (PTP). Also known as IEEE 1588, this protocol allows for synchronizing connected devices with sub-microsecond precision.

Re: [time-nuts] Teensy 4.1

I like the look of the 4.1 especially once they sell the Ethernet kit. I'll port my NTP/PTP server over to it as it is a lot smaller (and cheaper) than the current board that I'm using. Happily the Teensy is supported by ChibiOS which is the OS that I used before. Philip On Thu, May 14, 2020

[time-nuts] Alfred Loomis - an early time nut

> On 2020 May 14, at 14:21 , Skip Withrow > wrote: > […snip…] > > A question for TVB (or anyone else that might know), what happened to > the three Shortt clocks that he [Loomis] had? About 100 Shortt-Synchronome systems were manufactured. There is not a

Re: [time-nuts] Teensy 4.1

On 5/14/20 3:14 PM, Adrian Godwin wrote: I just saw an update to the Teensy microcontroller line. Teensys are somewhat like an arduino but generally with faster processors and more memory. The latest one, 4.1, has an ethernet interface with IEEE1588 packet timestamping.

Re: [time-nuts] Teensy 4.1

I just got a Teensy 4.0, OSHPark edition (it was $18 when I bought a set of boards a couple of weeks ago). I have not done anything with it yet but I am looking forward to. I have not looked at the differences with the 4.1. Didier KO4BB On Thu, May 14, 2020, 5:15 PM Adrian Godwin wrote: > I

[time-nuts] Teensy 4.1

I just saw an update to the Teensy microcontroller line. Teensys are somewhat like an arduino but generally with faster processors and more memory. The latest one, 4.1, has an ethernet interface with IEEE1588 packet timestamping. https://www.pjrc.com/category/news/ I'm not on pjrc's staff etc,

Re: [time-nuts] OCXO Support Board

Hi I would toss in: If you are starting from scratch, pick a program that allows you to easily enter schematics as well as PCB layouts. Take the time to learn both sides of the program. That will give you an automated check between the schematic and the layout….. It also gives you a document to

Re: [time-nuts] OCXO Support Board

Hi All, I will second Bob's comment on choosing a program with PCB - Schematic integration. I can heartily recommend Kicad. I own Altium designer, but work remotely for an American firm from Germany. The US office uses PADs. We have finally agreed on projects going forward to both use Kicad.

Re: [time-nuts] OCXO Support Board

Hi Going from “pro” layout tools to KiCad, the only big thing that seems to be missing is a “full feature” DRC (design rules check) process in KiCad. The tools I worked with in the past had much more fine grained rules checking features. Probably not a big deal for a basement project. It would