Re: [time-nuts] OCXO housings - Why copper and not iron/steel?

On 10/30/2020 5:05 PM, Bob kb8tq wrote: Hi Gradients are a really big deal in an OCXO. Thermal mass works against you if you are after quick warmup …. Bob I'll take this opportunity to plug my 1997 FCS paper: "The Theory of Zero Gradient Ovens" explaining how we got thermal gain over 1

Re: [time-nuts] OCXO housings - Why copper and not iron/steel?

Not true The Wiedemann-Franz gives the ratio of the thermal conductivity to electrical conductivity of a metal: ( pi^2 / 3 ) * ( (k/e)^2 ) * T Bruce > On 31 October 2020 at 12:49 "Dr. David Kirkby" > wrote: > > > On Fri, 30 Oct 2020 at 22:17, Luiz Alberto Saba wrote: > > > My bad...

Re: [time-nuts] OCXO housings - Why copper and not iron/steel?

Hi Gradients are a really big deal in an OCXO. Thermal mass works against you if you are after quick warmup …. Bob > On Oct 30, 2020, at 6:23 PM, Attila Kinali wrote: > > On Fri, 30 Oct 2020 17:58:24 -0400 > Bob kb8tq wrote: > >> Simple answer: conductivity. You don’t get much heat capacity

[time-nuts] OCXO housings - Why copper and not iron/steel?

And (if I remember the numbers properly) Isotopically pure diamond has twice the thermal conductivity of natural diamond. There are places that make diamond-like carbon thermal pads. Also places that make actual diamond ones (which are not as expensive as you would think),

Re: [time-nuts] OCXO housings - Why copper and not iron/steel?

Diamond, graphite and graphene are all forms of the element carbon. They all can have more conductivity than silver. Rick N6RK On 10/30/2020 3:25 PM, Andy Talbot wrote: Actually, diamond has five times better thermal conductivity than silver, so is the most conductive element, although

Re: [time-nuts] OCXO housings - Why copper and not iron/steel?

On Fri, 30 Oct 2020 at 22:17, Luiz Alberto Saba wrote: > My bad... copper is the second, losing only to silver, as a thermal > conductor. > I think you are mistaken. Copper is second to silver for *electrical* conductivity, but I doubt that is so for thermal conductivity. I think diamond,

Re: [time-nuts] OCXO housings - Why copper and not iron/steel?

Heat capacity is essentially a measure of how much heat a material can hold (to a first approximation). Thermal conductivity is a measure of how well a material moves heat between two different temperatures mechanically connected to the material. When using a material as a heat sink, one wants

Re: [time-nuts] OCXO housings - Why copper and not iron/steel?

Actually, diamond has five times better thermal conductivity than silver, so is the most conductive element, although graphene is suspected to be better still. Andy www.g4jnt.com Virus-free.

Re: [time-nuts] OCXO housings - Why copper and not iron/steel?

On Fri, 30 Oct 2020 17:58:24 -0400 Bob kb8tq wrote: > Simple answer: conductivity. You don’t get much heat capacity either way. Ah.. so it is more important to have less temperature gradients than having high capacity? Attila Kinali -- The bad part of Zurich is

Re: [time-nuts] OCXO housings - Why copper and not iron/steel?

My bad... copper is the second, losing only to silver, as a thermal conductor. Enviado do meu iPhone > Em 30 de out. de 2020, à(s) 19:06, Luiz Alberto Saba > escreveu: > > If my memory serves me, copper has the better conductivity of all the > periodic table... > > Enviado do meu iPhone >

Re: [time-nuts] OCXO housings - Why copper and not iron/steel?

Hi Simple answer: conductivity. You don’t get much heat capacity either way. Bob > On Oct 30, 2020, at 5:49 PM, Attila Kinali wrote: > > Moin, > > I have been looking at heat capacities of different materials > lately. One thing that struk me odd is, that the volumetric > heat capacity of

Re: [time-nuts] OCXO housings - Why copper and not iron/steel?

If my memory serves me, copper has the better conductivity of all the periodic table... Enviado do meu iPhone > Em 30 de out. de 2020, à(s) 18:56, Attila Kinali escreveu: > > Moin, > > I have been looking at heat capacities of different materials > lately. One thing that struk me odd is,

[time-nuts] OCXO housings - Why copper and not iron/steel?

Moin, I have been looking at heat capacities of different materials lately. One thing that struk me odd is, that the volumetric heat capacity of copper, which is the thing that most people use when building something that needs to have high heat capacity to get stable temperature, has only a

Re: [time-nuts] "When you google word ..."

t...@leapsecond.com said: > Right, OCXO are not stable enough at the desired tau to do a blueshift > experiment. So that's why atomic (and now, optical) clocks are used. But > note that many experimental confirmations of general relativity, from > planets to black holes, do not involve clocks,

[time-nuts] Changes in commercial GPS clocks over the decades

During my telco career I was responsible for Network Synchronization and witnessed several generations of clock designs. Post-telco I now manufacture and sell Network synchronization systems. Here are a few observations from legacy and modern topologies: 1. BITS clocks used to consume an

Re: [time-nuts] "When you google word ..."

Azelio, Right, OCXO are not stable enough at the desired tau to do a blueshift experiment. So that's why atomic (and now, optical) clocks are used. But note that many experimental confirmations of general relativity, from planets to black holes, do not involve clocks, per se. See, for

Re: [time-nuts] HP 5345A Noise Floor

Hi Ummm ….. er …… not so much :) The time base of the counter is only just so good. I would guess that there is a glitch somewhere in the data transfer / data file formatting. Bob > On Oct 30, 2020, at 1:14 PM, Giorgio Barinetti wrote: > > Hi Bob, > > > > The current setup is: >

[time-nuts] HP 5345A Noise Floor

Hi Bob, The current setup is: Counter locked ( 10 mhz in ) to the Cesium. Same 10 mhz signal from the Cesium feeds both the inputs and counter is running in “phase difference” so time A-B. That means the resolution will be hiher, I guess, since the counter is counting the

Re: [time-nuts] "When you google word ..."

The NIST seminars are interesting, but if you attend multiple years the material is nearly always the same. db -Original Message- From: time-nuts On Behalf Of Bob kb8tq Sent: Friday, October 30, 2020 7:56 AM To: Discussion of precise time and frequency measurement Subject: Re:

Re: [time-nuts] "When you google word ..."

Was the blueshift only ever tested by using atomic clocks? OK, OCXOs alone are not stable enough to try and we can't go that far from our planet with the necessary equipment. On Fri, Oct 30, 2020 at 2:27 PM Bob kb8tq wrote: > > Hi > > So there might be a reason (other than NIST) to believe that

Re: [time-nuts] Frequency Counter Choice

Just for reference, I have an HP5334 that is missing the entire display assembly and it works just fine over GPIB. Try it, it would most likely work. Didier KO4BB On Thu, Oct 22, 2020, 9:46 AM Mark Spencer wrote: > I am just curious how viable would it be to use a 531xx series counter > with

Re: [time-nuts] "When you google word ..."

Hi So there might be a reason (other than NIST) to believe that frequency and gravity are related to each other ? :) Bob > On Oct 30, 2020, at 7:28 AM, Tom Van Baak wrote: > > > Time Too Good to Be True, Daniel Kleppner > > Physics Today, March 2006, page 10 > >

Re: [time-nuts] SiTime Stratum 3E DCOCXO

Hi Indeed, they are pretty amazing for a tiny little part. Ultimately physics does catch up with them. The resonator in the heart of the device has it’s limitations compared to a big chunk of quartz. Things like ADEV or phase noise aren’t their strong suit when compared to a good OCXO. Note

Re: [time-nuts] "When you google word ..."

> Time Too Good to Be True, Daniel Kleppner > Physics Today, March 2006, page 10 > https://physicstoday.scitation.org/doi/10.1063/1.2195297 An adventure in relative time-keeping, Tom Van Baak Physics Today, March 2007, page 16 https://physicstoday.scitation.org/doi/10.1063/1.2718741 /tvb

[time-nuts] SiTime Stratum 3E DCOCXO

Does anyone have any knowledge of the suitability of these silicon vs quartz frequency sources for TimeNuts applications? https://www.sitime.com/products/stratum-3e-dcocxos/sit5721 The published specs seem quite remarkable for a device that is 5 x 7 x 9mm You have to request a data sheet,

Re: [time-nuts] "When you google word ..."

I am not sure why they would be discouraged.  We have known of the gravitational red-shift for a while and it is of course part of GPS calculations.  The Mossbauer effect, which involves a very narrow nuclear resonance, was used to demonstrate it in 1959 over a height of 22.5 meters (the

Re: [time-nuts] "When you google word ..."

fiber.g...@fiber.guru said: > One thing that was pretty cool is that NIST developed a fountain clock that > is so accurate it is influenced by altitude. They had to raise the clock > once to install a new floor beneath and when they raised the clock it > impacted the frequency. Originally