Re: [time-nuts] noise sources Re: Re. DIY atomic "resonator"

On 4/12/17 6:33 PM, Bob kb8tq wrote: Hi Back in the day (1960’s) noise diodes were quite a bit more expensive than they are today. Even today, a miniature lightbulb is quite a bit less expensive than a noise diode. You don’t go that way because it’s better. You go that way because it’s cheap

[time-nuts] Mini-circuits ZFSC-8-1 a a reference distribution

My UCT-2008 rubidium reference uses the same splitter. It is driven by a LPRO rubidium through an amplifier circuit which also drives a divider chain for producing several TTL level frequencies. One issue to be aware of with splitters can be poor reverse isolation of the outputs. I have not

Re: [time-nuts] Mini-circuits ZFSC-8-1 a a reference distribution

Hi A lot depends on what you are trying to do. The disadvantage of power splitters is isolation. A dirt cheap logic IC based distribution amp will easily beat them in this regard. That said, the splitters are quite easy to find and hook up.They also are pretty much indestructible (at least I’ve

Re: [time-nuts] OCXO Soft-Start

10.9 MHz is likely the B-mode of the SC cut. (It's a different mode, not a different overtone). This mode has a tempco of 20 ppm and is used to do thermometry. IMHO, there is NO excuse for the oscillator designer to design an oscillator that doesn't oscillate unconditionally in the right mode.

Re: [time-nuts] Re. DIY atomic "resonator"

Typically External Cavity diode lasers use either the Littrow or the Littman-Metcalf configurations. A typical Littrow configuration is: http://www.moglabs.com/uploads/2/4/2/1/24212474/manual_ecd_rev4.20.pdf Alternatively a cat eye external cavity can be used:

Re: [time-nuts] noise sources Re: Re. DIY atomic "resonator"

Hi Back in the day (1960’s) noise diodes were quite a bit more expensive than they are today. Even today, a miniature lightbulb is quite a bit less expensive than a noise diode. You don’t go that way because it’s better. You go that way because it’s cheap …. Bob > On Apr 12, 2017, at 7:04 PM,

[time-nuts] Mini-circuits ZFSC-8-1 a a reference distribution

Hello all, Reading the list so long I thought I was a member until I tried to post today. I recently purchased the subject device, Mini-circuits ZFSC-8-1 , for distributing the 10Mhz reference from my Lucent

Re: [time-nuts] OCXO Soft-Start

Hi A SC cut crystal has multiple resonance “modes” in can operate on. This is in addition to the normal set of fundamental, third overtone, fifth overtone and so on. For various interesting reasons the SC modes are called A, B and C. On a normal 10 MHz crystal, the “main mode” is the C mode.

Re: [time-nuts] Re. DIY atomic "resonator"

One of the challenges with todays new WiFi standards i.e. 802.11ac/ad/ax is the doppler from office fluorescent lighting systems so much so that channel emulators like the Anite Propsim F8 emulate it at various pseudoranges to the AP and STA That said old school noise sources were indeed gas

[time-nuts] noise sources Re: Re. DIY atomic "resonator"

On 4/12/17 1:23 PM, Bob kb8tq wrote: Hi *All* incandescent lamps emit RF ….. They are a resistive device that is heated to well above room temperature. People do use them in simple noise figure meters. The inductance of the filament in a typical bulb restricts the bandwidth a bit. The are

[time-nuts] OCXO Soft-Start

Hello, I wanted to see if I could soft-start a used OCXO (Trimble 34310) during warm-up. By default with an appropriately rated 12 VDC supply, the OCXO starts the heater at about 8 W, and eventually settles down to 2 W for 20-25 degC ambient temperature. Figure Attached. The good news is it does

Re: [time-nuts] Re. DIY atomic "resonator"

Hi There are papers from the mid 90’s talking about improving the GPS Rb’s. Those parts are as far as I know the best “production” Rb’s out there. The main comment seems to be that phase noise (in it’s various forms) is a major contributor to the stability of the Rb’s…. Bob > On Apr 12,

Re: [time-nuts] Re. DIY atomic "resonator"

Many decades ago, QST had an article about the "Monode" RF noise generator. No it wasn't an April Fools joke; the Monode is simply a light bulb. You can probably download the article from the arrl.org web site. HP used to sell a fluorescent tube embedded in a waveguide as a noise source.

Re: [time-nuts] UltrAtomic® Clock

My long-time (and accurate) 12-inch analog kitchen clock (24 years) dropped to floor in March, as I was adjusting for Daylight Savings Time. Of course, the polycarbonate lens cover cracked and I could not find a replacement. The manufacturer, General Time of Athens, GA (handled Seth Thomas,

Re: [time-nuts] Car Clock drift - the lowly 32kHz tuning fork

> I'm actually speaking with one of Ed Boyden's students today who is > interested in biosecurity! Small world, but I'm getting used to that for things like this. "biosecurity" gets interesting when you have probes directly into the brain. Do you know if the folks working on electronics to

Re: [time-nuts] Re. DIY atomic "resonator"

Hi *All* incandescent lamps emit RF ….. They are a resistive device that is heated to well above room temperature. People do use them in simple noise figure meters. The inductance of the filament in a typical bulb restricts the bandwidth a bit. The are designs from at least the 1960’s

Re: [time-nuts] Re. DIY atomic "resonator"

Looking back at the dialog I started on Rb’s and the repeated returns to that subject allow me to make some comments, observations and recommendations.. I stayed on purpose away from participating but learned a lot. It also resulted in some off list dialogs with members working on the

Re: [time-nuts] Re. DIY atomic "resonator"

On Wed, Apr 12, 2017 at 11:18:00AM -0700, jimlux wrote: > Yep. There's been a fair amount of work over the past decades on using > modulated reflectors for measuring antenna patterns (e.g. on phased > arrays). You can have a diode/dipole suspended by resistive leads (with > an impedance of

Re: [time-nuts] Re. DIY atomic "resonator"

Some incandescent lamps can emit RF. http://www.rexophone.com/?p=1081 http://www.radiomuseum.org/forum/rustika_lightbulb_fm_measurements.html On Tue, 11 Apr 2017 18:09:52 +, you wrote: >Apparently fluorescent tubes continuously emit a lot of other microwave >signals. I once built a

Re: [time-nuts] Car Clock drift - the lowly 32kHz tuning fork

I worked on a project once where a part was temperature sensitive. Another engineer, not me stuck a Peltier device on the part along with a temperature sensor and a crude servo using an op amp. This was not complex, a simple design and it held to about 1/2 degree C.Basically made an

Re: [time-nuts] Re. DIY atomic "resonator"

On 4/12/17 10:28 AM, Dave B via time-nuts wrote: On 12/04/17 17:00, jimlux wrote: Subject: Re: [time-nuts] Re. DIY atomic "resonator" Message-ID: Content-Type: text/plain; charset=utf-8; format=flowed On 4/11/17 11:09 AM, Mark Sims wrote:

Re: [time-nuts] Re. DIY atomic "resonator"

On 12/04/17 17:00, "Tom Van Baak" wrote: > It turns out that OP (Andre) would like the readings of his vintage Black > Star (UK) Nova 2400[X] 8-digit 2.4 GHz bench frequency counter to be accurate > and stable to the 8th digit. That's all. The internal XO or TCXO is not good > enough for that

[time-nuts] Ground state: Hans Dehmelt

In the news today... Hans Dehmelt (1922 - 2017) passed away a few weeks ago. He shared the 1989 Nobel prize in Physics with Wolfgang Paul for his work on trapped ions, which have application in ultra-stable ion atomic clocks. While many of us still play with rubidium vapor or cesium beam

[time-nuts] Three-cornered hat on timelab?

It was mentioned that Timelab can do a three-cornered hat.  I can't find it.  Is this something that can only be done with multiple Timepods connected, or is there an option that I'm missing?  Or is there some other tool that needs to be used?  For the record, I want to create the 3c-hat from

Re: [time-nuts] Re. DIY atomic "resonator"

On 12/04/17 17:00, jimlux wrote: > Subject: Re: [time-nuts] Re. DIY atomic "resonator" > Message-ID: > Content-Type: text/plain; charset=utf-8; format=flowed > > On 4/11/17 11:09 AM, Mark Sims wrote: >> Apparently fluorescent tubes continuously

Re: [time-nuts] a link to a explanation of Rb vs Cs?

Hi, On 04/12/2017 12:15 AM, Richard (Rick) Karlquist wrote: The "magic" of Rb in a gas cell standard is that you can make an optical filter cell out of radioactive Rb87 isotope that allows you to selectively optically pump to the quantum level you need. It is just "luck" that the absorption

Re: [time-nuts] Re. DIY atomic "resonator"

Hi According to the data sheet the X version of the 2400 has a TCXO in it. The “not an X” has an XO. “Setability” of the XO is <0.5 ppm and the TCXO is rated at 0.2 ppm. Maximum resolution on the device occurs with a 20 MHz input. That gives you +/- 0.05 ppm. The 200 MHz range is scaled by 10

Re: [time-nuts] Re. DIY atomic "resonator"

I investigated police radar stuff a long time ago, and for a while had an old X band unit shaped just like a searchlight, with analog meter. What I learned then was that even on the newer units, the tuning fork was specified to provide an independent means to verify the accuracy of the unit in

Re: [time-nuts] Re. DIY atomic "resonator" 6GHz synthesizer from ADI

But it is as Richard said and after he sent it I remembered reading about it in the "Quantum beat". The trick is to get that accurate frequencies sideband to land on the RB or CS frequency. Just 1 sideband. So using a large step synthesizer and then another to get the finer detail is a reasonable

Re: [time-nuts] Re. DIY atomic "resonator"

On 4/11/17 11:09 AM, Mark Sims wrote: Apparently fluorescent tubes continuously emit a lot of other microwave signals. I once built a homodyne doppler "speed" radar kit (used a coffee can for the antenna). The way you calibrated it was to point it at a florescent tube and and adjust the

Re: [time-nuts] Re. DIY atomic "resonator"

An update about this thread... It turns out that OP (Andre) would like the readings of his vintage Black Star (UK) Nova 2400[X] 8-digit 2.4 GHz bench frequency counter to be accurate and stable to the 8th digit. That's all. The internal XO or TCXO is not good enough for that last digit or two.

Re: [time-nuts] a link to a explanation of Rb vs Cs?

A little of the thinking, and a bit of the history of the rb v cs is in "CESIUM AND RUBIDIUM FREQUENCY STANDARDS STATUS AND PERFORMANCE ON THE GPS PROGRAM" http://www.stanson.ch/files/GPS/Vol%2027_14.pdf Ole > Den 12. apr. 2017 kl. 08.41 skrev Hal Murray : > > >

Re: [time-nuts] a link to a explanation of Rb vs Cs?

Hi If you take a look at the standard weekly publications, the GPS system runs on Rb’s. There is always one sat that has a Cs turned on. That’s been true as long as they have been running the system. The simple answer for that choice is that the Rb’s are easier to predict (better short term to

Re: [time-nuts] TAPR TICC boxed (input protection)

They are relevant when a high input impedance buffer is used making it easier to add series/shunt overload protection. Protecting against 400 volts and higher is feasible this way. Adding overload protection to a 50 ohm input is an interesting challenge but it can be done. Precede the 50 ohm

[time-nuts] Re. DIY atomic "resonator"

Apparently fluorescent tubes continuously emit a lot of other microwave signals. I once built a homodyne doppler "speed" radar kit (used a coffee can for the antenna). The way you calibrated it was to point it at a florescent tube and and adjust the reading to a specific value.

Re: [time-nuts] a link to a explanation of Rb vs Cs?

jim...@earthlink.net said: > If there's nothing folks are aware of, I'll probably see if I can find some > nice schematic pictures of a Cs Beam, a gas cell, and an Hg ion trap, and > then a AVAR plot or something. I think the GPS satellites have 3 Cs and 2 Rbs. There might be an interesting