Re: [time-nuts] Tbolt issues

On 9/1/16 5:51 PM, Charles Steinmetz wrote: Nick wrote: On a theoretical basis, can one speak of the limit of the frequency observed as tau approaches zero? Might that in some way be the "instantaneous frequency" which people often think of? That is (or is "something like") what it *would*

Re: [time-nuts] Tbolt issues

Nick wrote: On a theoretical basis, can one speak of the limit of the frequency observed as tau approaches zero? Might that in some way be the "instantaneous frequency" which people often think of? That is (or is "something like") what it *would* be, but a little thought experiment will

Re: [time-nuts] Tbolt issues

Hi Unfortunately if you read a typical text on FM modulation, "instantaneous frequency" comes up pretty fast. In that context it has a valid meaning. Once out of context, it gets you in trouble. That point is never made when the term is introduced. Bob > On Sep 1, 2016, at 8:51 PM, Charles

Re: [time-nuts] Tbolt issues

Bert wrote: maybe some one smarter than us can working with the parameters that Tbolt makes available better performance can be achieved I am quite sure of that the frequency is being changed to compensate for time Yes, the PPS is steered by making slight adjustments to the OCXO

Re: [time-nuts] Tbolt issues

Hi Frequency is a "change over time". If delta time is zero it is undefined. As you observe it in shorter time periods, the accuracy / stability gets worse. Since the error bars expand there isn't much of a limit as you go shorter. They are not quite the same thing, but they are related. Bob

Re: [time-nuts] Tbolt issues

Tom wrote: No, again it sounds like you have a bad TBolt. Or something is wrong (antenna? reception? time constant? environment? China resoldered parts?). I appreciate that Juerg did lots of testing -- do you happen to have his ADEV plot? Your claim of 1e-10 is order(s) of magnitude worse

Re: [time-nuts] Tbolt issues

Hi The problem with absolute frequency is the one they ran into in the 60’s (and before): There is no really good way to measure it. You certainly can take data. The data can have lots of resolution. That part has always been fairly easy. The problem is that the more carefully you look,

Re: [time-nuts] Tbolt issues

maybe some one smarter than us can working with the parameters that Tbolt makes available better performance can be achieved but it is a fact that the frequency is being changed to compensate for time and Tom's frequency data matches our's and we do not care about ADEV, we care about the

Re: [time-nuts] Tbolt issues

For us it is absolute Frequency, to me it is a measure of true performance. In a message dated 9/1/2016 4:52:35 P.M. Eastern Daylight Time, kb...@n1k.org writes: Hi I think one issue here is that ADEV is being used by one “lab" and absolute frequency is being used by the other. They

Re: [time-nuts] Tbolt issues

Hi I think one issue here is that ADEV is being used by one “lab" and absolute frequency is being used by the other. They very much are *not* the same thing. There isn’t even a really simple way to convert one to the other. There will always be a big delta between those two measures. For

Re: [time-nuts] Tbolt issues

On Thu, September 1, 2016 11:54 am, Bert Kehren via time-nuts wrote: > All the power work will not improve the frequency performance > of the unit because the frequency is constantly changed > to correct time. Can't you control that to a large extent with the damping and time constant

[time-nuts] Tbolt issues

We have been following the Tbolt power discussions but what I am missing is the main problem with Tbolts. All the power work will not improve the frequency performance of the unit because the frequency is constantly changed to correct time. Tbolt is an excellent time device but not good for

Re: [time-nuts] Anybody want a Thunderbolt power supply?

James wrote: Is there a problem running more than one Thunderbolt off of the same linear supply (assuming the supply can support the current demands) or does each Thunderbolt require its’ own separate linear supply? I do not anticipate that multiple Tbolts would interact in a negative

Re: [time-nuts] Anybody want a Thunderbolt power supply?

Jim, I use a HP 6236B triple power supply to drive 2 each T'Bolts. Works fine after the T'Bolts warm up, with limitations on a cold start up. But once they warm up all is OK. Using a common outside puck antenna and a HP RF distribution block I can run 3 T'Bolts and get essentially the same

Re: [time-nuts] Anybody want a Thunderbolt power supply

Am 01.09.2016 um 16:36 schrieb jimlux: On 8/31/16 10:24 PM, Gerhard Hoffmann wrote: Am 01.09.2016 um 06:07 schrieb Bruce Griffiths: I have a quad LT3042 PCB that I must get around to assembling.One potential issue with the LT3042 is the relatively high noise at low frequencies when the

Re: [time-nuts] Anybody want a Thunderbolt power supply?

Hi The easy answer for a couple dozen Tbolts is a +15 V high current linear supply and a low power -15 V linear. Wire them to regulators mounted on chunks of perf board. Bob > On Sep 1, 2016, at 12:24 AM, DaveH wrote: > > Someone could come out with a circuit

Re: [time-nuts] Anybody want a Thunderbolt power supply?

Hi The gotcha is that an OCXO acts as a negative resistance load (current goes up as voltage goes down). That makes wiring up multiple units problematic. It is not impossible to do, but you can get in trouble. Putting regulation at each device eliminates the problem. It may be overkill, but

Re: [time-nuts] Anybody want a Thunderbolt power supply

On 8/31/16 10:24 PM, Gerhard Hoffmann wrote: Am 01.09.2016 um 06:07 schrieb Bruce Griffiths: I have a quad LT3042 PCB that I must get around to assembling.One potential issue with the LT3042 is the relatively high noise at low frequencies when the capacititve bypassing of the resistor that sets

Re: [time-nuts] Anybody want a Thunderbolt power supply

Dave wrote: The problem on eBay is "tested" means something quite different to what I know as "tested' Well, yes, but that's well-known. Ebay is what it is and ebay sellers are what they are. No use grousing about it, just deal with it. The important thing is to make sure you have a

Re: [time-nuts] Anybody want a Thunderbolt power supply?

Hi For multiple TBolts, the simple answer is local regulation. LT1764’s work fine for the +12 and +5 side. A well bypassed 79L12 can do the trick for the -12. Feed them all of of a bulk +15 (high current) llinear supply and a -15 with the lowest output you can find. The gotcha is that if you

Re: [time-nuts] Anybody want a Thunderbolt power supply?

Is there a problem running more than one Thunderbolt off of the same linear supply (assuming the supply can support the current demands) or does each Thunderbolt require its’ own separate linear supply? Jim Robbins ___ time-nuts mailing list --

Re: [time-nuts] Anybody want a Thunderbolt power supply

Mike wrote: I use the TAPR HPSDR LPU I was unfamiliar with the LPU, so I took a look at the docs. It develops several voltages, all from a +13.8v source. This means that the -12v supply necessarily is a switching supply (to get the polarity reversal). It is unfortunate that the power

Re: [time-nuts] Anybody want a Thunderbolt power supply

On 2016-09-01 05:35, Charles Steinmetz wrote: Bruce wrote: Low noise regulators for the +12V and +5V outputs would also be useful. Very true. By focusing on the -12v supply, I did not intend to suggest that low noise is unimportant on the +12v and +5v supplies. The suggestion to use

Re: [time-nuts] Anybody want a Thunderbolt power supply

Am 01.09.2016 um 07:44 schrieb Charles Steinmetz: The datasheet shows both NPN and PNP current multipliers. Just curious -- did you choose the NPN circuit for theoretical considerations, and if so what was your reasoning -- the lower open-loop output impedance? More belly feeling. The PNP

Re: [time-nuts] Anybody want a Thunderbolt power supply?

Original message From: Charles Steinmetz Date:09/01/2016 06:07 (GMT+00:00) To: time-nuts@febo.com Subject: Re: [time-nuts] Anybody want a Thunderbolt power supply? Randall wrote: > Tested and guaranteed samples of all of these can be bought for $25-100 if you are

Re: [time-nuts] Anybody want a Thunderbolt power supply

Bruce wrote: It will show up if the value of the voltage setting bypass capacitor is reduced. Both the Johnson and excess noise in this resistor coupled with the current source flicker noise should become evident. The datasheet graphs indicate that the Johnson noise of the voltage setting

Re: [time-nuts] Anybody want a Thunderbolt power supply?

Post should have been: Acts like noise current flowing in the voltage setting network (R || C).Flicker noise appears to kick in below 1Hz or so. Bruce On Thursday, 1 September 2016 8:23 PM, Bruce Griffiths wrote: Acts like current  noise flowing in the

Re: [time-nuts] Anybody want a Thunderbolt power supply

I wrote: I have converted a number of them by replacing the DC-DC converters and feeding the circuitry from a mains-operated linear DC supply This should read, "I have converted a number of them by *removing* the DC-DC converters and feeding the circuitry from a mains-operated linear DC

Re: [time-nuts] Anybody want a Thunderbolt power supply

Gerhard wrote: I have made a stamp-sized layout for LT3042 + external npn power transistor as shown in the data sheet. Not fabricated, let alone tested. Nice! The datasheet shows both NPN and PNP current multipliers. Just curious -- did you choose the NPN circuit for theoretical

Re: [time-nuts] Anybody want a Thunderbolt power supply?

Randall wrote: Wow, given all the responses about the cleanliness of the power into a Thunderbolt, I would be even more interested in a power supply that did *not* leave the "last mile" up to me. I would be more interested in a "pretty clean" power supply that I could just plug in and go.

Re: [time-nuts] Anybody want a Thunderbolt power supply

Dave wrote: Getting the required Thunderbolt supply rails from a nominal 12v dc supply of doubtful cleanliness is an issue that also needs to be addressed. I'm still mulling over that one. (and using a triple output switcher from an inverter backed mains supply meantime!) The ex-telco GPSDOs

Re: [time-nuts] Anybody want a Thunderbolt power supply

It will show up if the value of the voltage setting bypass capacitor is reduced. Both the Johnson and excess noise in this resistor coupled with the current source flicker noise should become evident. The datasheet graphs indicate that the Johnson noise of the voltage setting resistor(33k2