Re: [time-nuts] Anyone Know What The Models Were In This NIST Paper?
John the problem is the NIST does not endorse one brand vs another. They go to great lengths to stay neutral. But if knowledge of the products used sheds light on the research it is not a usually a problem. I would say an educated guess the 6 and 8 channel receivers were oncores, and the rubidium oscillators were LPRO's. Thomas Knox From: j...@westmorelandengineering.com Date: Tue, 29 Oct 2013 19:06:25 -0700 To: time-nuts@febo.com Subject: Re: [time-nuts] Anyone Know What The Models Were In This NIST Paper? Bob, Yes - well, it is a little dated - so I would think the chance for a competitive edge would have expired. Maybe not for models C and D but I would certainly think so for Models A B. There must be some sort of technical statute of limitations, correct? ;) Regards, John Westmoreland On Tue, Oct 29, 2013 at 6:31 PM, Bob Camp li...@rtty.us wrote: Hi That’s always one of those “we can only tell you if you work for the US government” sort of things. If anybody knows it’s one of those “you better not tell” things. Bob On Oct 29, 2013, at 8:40 PM, John C. Westmoreland, P.E. j...@westmorelandengineering.com wrote: Hello, Does anyone know what Models A, B, C, and D were in this paper? Or maybe had a good idea? http://www.nist.gov/customcf/get_pdf.cfm?pub_id=50196 Thanks! John Westmoreland ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Anyone Know What The Models Were In This NIST Paper?
Hi I believe that Jim is more or less right. There seems to be an agreement not to name names. I’m sure it’s partly to keep everybody happy when the paper is presented. It also does relate to some sort of rules and regs. Bob On Oct 30, 2013, at 3:00 AM, Tom Knox act...@hotmail.com wrote: John the problem is the NIST does not endorse one brand vs another. They go to great lengths to stay neutral. But if knowledge of the products used sheds light on the research it is not a usually a problem. I would say an educated guess the 6 and 8 channel receivers were oncores, and the rubidium oscillators were LPRO's. Thomas Knox From: j...@westmorelandengineering.com Date: Tue, 29 Oct 2013 19:06:25 -0700 To: time-nuts@febo.com Subject: Re: [time-nuts] Anyone Know What The Models Were In This NIST Paper? Bob, Yes - well, it is a little dated - so I would think the chance for a competitive edge would have expired. Maybe not for models C and D but I would certainly think so for Models A B. There must be some sort of technical statute of limitations, correct? ;) Regards, John Westmoreland On Tue, Oct 29, 2013 at 6:31 PM, Bob Camp li...@rtty.us wrote: Hi That’s always one of those “we can only tell you if you work for the US government” sort of things. If anybody knows it’s one of those “you better not tell” things. Bob On Oct 29, 2013, at 8:40 PM, John C. Westmoreland, P.E. j...@westmorelandengineering.com wrote: Hello, Does anyone know what Models A, B, C, and D were in this paper? Or maybe had a good idea? http://www.nist.gov/customcf/get_pdf.cfm?pub_id=50196 Thanks! John Westmoreland ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Surface Mount OCXO Questions
Hi There are a *lot* of SMT OCXO’s out there. A J lead part is SMT, but identical to it’s through hole counterpart. It will mount pretty much same / same…. Bob On Oct 29, 2013, at 10:18 PM, John C. Westmoreland, P.E. j...@westmorelandengineering.com wrote: Hello, I was wondering if I could get some recommendations on surface mount OCXO's vs. the traditional through hole. I was also wondering on the board layout - if you found it necessary to leave a thermal moat so to speak - and what worked best. Maybe the OCXO has an internal air barrier that maybe would make this unnecessary - not sure. Your input and experience appreciated. Thanks, John Westmoreland ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Surface Mount OCXO Questions
John: All SMT OCXO's will either have a recommended PCB footprint in the spec sheet or will refer you to a recommended footprint in another document. Some don't care about a ground plane under the part, some require it with no crossing signals, some require an open thermal hole underneath the oven. I have seen all three cases. As usual, it is suggested that you read the [] manual. Best regards, --- Graham / KE9H == On 10/29/2013 9:18 PM, John C. Westmoreland, P.E. wrote: Hello, I was wondering if I could get some recommendations on surface mount OCXO's vs. the traditional through hole. I was also wondering on the board layout - if you found it necessary to leave a thermal moat so to speak - and what worked best. Maybe the OCXO has an internal air barrier that maybe would make this unnecessary - not sure. Your input and experience appreciated. Thanks, John Westmoreland ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Anyone Know What The Models Were In This NIST Paper?
Hi, They have learned the hard way that they can't do that easily. They can, if they add the necessary mentioning of vendor X and their product Y does in no way means an endorsement. I've seen presentations starting with a non-endorsement statement so that they can then say Oh, this is the boxes we have chosen to use, which tends to just render spread of information and sharing of experience amongst the users. I expect them (NIST and other publicly funded institutions) to act like this. It is a bit annoying when you just want to know what they where using, but it's understandable. It is even more understandable as they start to list miss-features of device A, B and C, but not device D. It's a balance to share information which can be very useful, but not cause people to be upset by being left out or feeling discredited. When working on the commercial side of things, I try to respect this restriction and assume it's usage, while trying to find a suitable compromise at times. The same goes when writing standards. Cheers, Magnus On 10/30/2013 12:12 PM, Bob Camp wrote: Hi I believe that Jim is more or less right. There seems to be an agreement not to name names. I’m sure it’s partly to keep everybody happy when the paper is presented. It also does relate to some sort of rules and regs. Bob On Oct 30, 2013, at 3:00 AM, Tom Knox act...@hotmail.com wrote: John the problem is the NIST does not endorse one brand vs another. They go to great lengths to stay neutral. But if knowledge of the products used sheds light on the research it is not a usually a problem. I would say an educated guess the 6 and 8 channel receivers were oncores, and the rubidium oscillators were LPRO's. Thomas Knox From: j...@westmorelandengineering.com Date: Tue, 29 Oct 2013 19:06:25 -0700 To: time-nuts@febo.com Subject: Re: [time-nuts] Anyone Know What The Models Were In This NIST Paper? Bob, Yes - well, it is a little dated - so I would think the chance for a competitive edge would have expired. Maybe not for models C and D but I would certainly think so for Models A B. There must be some sort of technical statute of limitations, correct? ;) Regards, John Westmoreland On Tue, Oct 29, 2013 at 6:31 PM, Bob Camp li...@rtty.us wrote: Hi That’s always one of those “we can only tell you if you work for the US government” sort of things. If anybody knows it’s one of those “you better not tell” things. Bob On Oct 29, 2013, at 8:40 PM, John C. Westmoreland, P.E. j...@westmorelandengineering.com wrote: Hello, Does anyone know what Models A, B, C, and D were in this paper? Or maybe had a good idea? http://www.nist.gov/customcf/get_pdf.cfm?pub_id=50196 Thanks! John Westmoreland ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Anyone Know What The Models Were In This NIST Paper?
On 10/30/13 3:46 PM, Magnus Danielson wrote: Hi, They have learned the hard way that they can't do that easily. They can, if they add the necessary mentioning of vendor X and their product Y does in no way means an endorsement. I've seen presentations starting with a non-endorsement statement so that they can then say Oh, this is the boxes we have chosen to use, which tends to just render spread of information and sharing of experience amongst the users. I expect them (NIST and other publicly funded institutions) to act like this. It is a bit annoying when you just want to know what they where using, but it's understandable. It is even more understandable as they start to list miss-features of device A, B and C, but not device D. It works both ways, when you have a device that you're particularly proud of, and it performs well in the tests, you want them to say Jim Lux's fabulous device performed orders of magnitude better than all other devices tested, particularly the unusually poor performance from the device from Magnus Danielson grin. But there are also other forces at work. There are cases where IEEE and authors were sued because of a paper that essentially said that a particular product not only didn't work, but that underlying physics guaranteed that it couldn't work. (early streamer emission devices, and a paper by Mousa, in particular) It would be an amusing story, if all the litigation hadn't happened. For instance, Mousa reports on one installation where the lightning eliminator was completely destroyed by a lightning stroke. The traffic controllers at Tampa saw a flash of light during a storm, heard thunder and observed a shower of sparks drop past the tower window. A later visit to the rooftop revealed that a part of the charge dissipater array of Manufacturer “A” had disappeared. that would tend to drive authors to such circumlocutions as Brand X, etc. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Anyone Know What The Models Were In This NIST Paper?
On 10/31/2013 12:14 AM, Jim Lux wrote: On 10/30/13 3:46 PM, Magnus Danielson wrote: Hi, They have learned the hard way that they can't do that easily. They can, if they add the necessary mentioning of vendor X and their product Y does in no way means an endorsement. I've seen presentations starting with a non-endorsement statement so that they can then say Oh, this is the boxes we have chosen to use, which tends to just render spread of information and sharing of experience amongst the users. I expect them (NIST and other publicly funded institutions) to act like this. It is a bit annoying when you just want to know what they where using, but it's understandable. It is even more understandable as they start to list miss-features of device A, B and C, but not device D. It works both ways, when you have a device that you're particularly proud of, and it performs well in the tests, you want them to say Jim Lux's fabulous device performed orders of magnitude better than all other devices tested, particularly the unusually poor performance from the device from Magnus Danielson grin. No need to write that, as it is common knowledge that MD's device is not only of inferior quality and performance, but the residue of a hedgehog nest, at best. grin But there are also other forces at work. There are cases where IEEE and authors were sued because of a paper that essentially said that a particular product not only didn't work, but that underlying physics guaranteed that it couldn't work. (early streamer emission devices, and a paper by Mousa, in particular) It would be an amusing story, if all the litigation hadn't happened. For instance, Mousa reports on one installation where the lightning eliminator was completely destroyed by a lightning stroke. The traffic controllers at Tampa saw a flash of light during a storm, heard thunder and observed a shower of sparks drop past the tower window. A later visit to the rooftop revealed that a part of the charge dissipater array of Manufacturer “A” had disappeared. that would tend to drive authors to such circumlocutions as Brand X, etc. Oh yes. But we do these things over at this side of the pond, without having the use of the legal system, as seems customary on your side of the pond. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Surface Mount OCXO Questions
Graham and Time Nuts, (thanks for the answers.) I have another question - I am looking at a part from MTI. I wanted to use one of their 3.3V parts. They are telling me to use the 12V part because the 3.3V part can have an issue with ground loops due to the higher current requirements at that voltage for the oven. Have any of you experienced this? Makes me wonder a little why they offer the 3.3V part. It would seem good layout can control any possibility of ground loops becoming a problem. Thanks and Regards, John W./AJ6BC On Wed, Oct 30, 2013 at 6:54 AM, Graham / KE9H time...@austin.rr.comwrote: John: All SMT OCXO's will either have a recommended PCB footprint in the spec sheet or will refer you to a recommended footprint in another document. Some don't care about a ground plane under the part, some require it with no crossing signals, some require an open thermal hole underneath the oven. I have seen all three cases. As usual, it is suggested that you read the [] manual. Best regards, --- Graham / KE9H == On 10/29/2013 9:18 PM, John C. Westmoreland, P.E. wrote: Hello, I was wondering if I could get some recommendations on surface mount OCXO's vs. the traditional through hole. I was also wondering on the board layout - if you found it necessary to leave a thermal moat so to speak - and what worked best. Maybe the OCXO has an internal air barrier that maybe would make this unnecessary - not sure. Your input and experience appreciated. Thanks, John Westmoreland __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Surface Mount OCXO Questions
Hi Consider that microvolts matter on the EFC. Unless you have a separate return for the oven current it’s going to be tough to keep everything separate. One might ask “why no separate return”. Well when you design one in, and then go look at people’s layouts - you might as well not have designed it in ….. Bob On Oct 30, 2013, at 8:37 PM, John C. Westmoreland, P.E. j...@westmorelandengineering.com wrote: Graham and Time Nuts, (thanks for the answers.) I have another question - I am looking at a part from MTI. I wanted to use one of their 3.3V parts. They are telling me to use the 12V part because the 3.3V part can have an issue with ground loops due to the higher current requirements at that voltage for the oven. Have any of you experienced this? Makes me wonder a little why they offer the 3.3V part. It would seem good layout can control any possibility of ground loops becoming a problem. Thanks and Regards, John W./AJ6BC On Wed, Oct 30, 2013 at 6:54 AM, Graham / KE9H time...@austin.rr.comwrote: John: All SMT OCXO's will either have a recommended PCB footprint in the spec sheet or will refer you to a recommended footprint in another document. Some don't care about a ground plane under the part, some require it with no crossing signals, some require an open thermal hole underneath the oven. I have seen all three cases. As usual, it is suggested that you read the [] manual. Best regards, --- Graham / KE9H == On 10/29/2013 9:18 PM, John C. Westmoreland, P.E. wrote: Hello, I was wondering if I could get some recommendations on surface mount OCXO's vs. the traditional through hole. I was also wondering on the board layout - if you found it necessary to leave a thermal moat so to speak - and what worked best. Maybe the OCXO has an internal air barrier that maybe would make this unnecessary - not sure. Your input and experience appreciated. Thanks, John Westmoreland __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Surface Mount OCXO Questions
Bob, OK - that makes sense. If you follow good analog/digital layout rules then this may not be a problem. But your point about the EFC sensitivity is well taken. But, that is always a problem. Yes, do a lot of people violate good analog/digital layout rules, especially on the ground planes - yep. This is exactly why I am asking these questions. Even in manufacturer's recommended layout instructions you can find mistakes. Unless you have a dev board that you have used and have the gerbers from that board so you know exactly how that part behaves with that layout - you cannot know for sure you have a sound layout for your design. You also have to be careful with board material, dielectrics, and copper weight, not to mention controlled impedances. Remember the early days of DC/DC converters? Thanks! John / AJ6BC On Wed, Oct 30, 2013 at 5:52 PM, Bob Camp li...@rtty.us wrote: Hi Consider that microvolts matter on the EFC. Unless you have a separate return for the oven current it’s going to be tough to keep everything separate. One might ask “why no separate return”. Well when you design one in, and then go look at people’s layouts - you might as well not have designed it in ….. Bob On Oct 30, 2013, at 8:37 PM, John C. Westmoreland, P.E. j...@westmorelandengineering.com wrote: Graham and Time Nuts, (thanks for the answers.) I have another question - I am looking at a part from MTI. I wanted to use one of their 3.3V parts. They are telling me to use the 12V part because the 3.3V part can have an issue with ground loops due to the higher current requirements at that voltage for the oven. Have any of you experienced this? Makes me wonder a little why they offer the 3.3V part. It would seem good layout can control any possibility of ground loops becoming a problem. Thanks and Regards, John W./AJ6BC On Wed, Oct 30, 2013 at 6:54 AM, Graham / KE9H time...@austin.rr.com wrote: John: All SMT OCXO's will either have a recommended PCB footprint in the spec sheet or will refer you to a recommended footprint in another document. Some don't care about a ground plane under the part, some require it with no crossing signals, some require an open thermal hole underneath the oven. I have seen all three cases. As usual, it is suggested that you read the [] manual. Best regards, --- Graham / KE9H == On 10/29/2013 9:18 PM, John C. Westmoreland, P.E. wrote: Hello, I was wondering if I could get some recommendations on surface mount OCXO's vs. the traditional through hole. I was also wondering on the board layout - if you found it necessary to leave a thermal moat so to speak - and what worked best. Maybe the OCXO has an internal air barrier that maybe would make this unnecessary - not sure. Your input and experience appreciated. Thanks, John Westmoreland __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nuts https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nuts https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] GPSDO choices
Is this JL LC_XO at around $300 going to supress the used Trimble/Zwhatever market price? I hope so. I think I would have put out the $ for this one rather than a 10 or more year old used piece of equipment. I still may do it. I just need to justify it somehow. Dave N3DT ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] New NTBW50AA
I've been living with this Nortel unit for over a month now and moved the antenna all over the place, plus made a different antenna and nothing seems to change as far as the Osc ppt/div. So I'm giving up and just going to install the antenna where it seems to get the best signal strength. I think at some point I may take the unit somewhere it's got a good view of the sky with no trees/leaves/antennas/etc to the view and see what it does. Otherwise it seems to be stable enough as far as I can tell. Dave N3DT ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO choices
Dave, I have an LC_XO and a GPSDO, both from Jackson Labs. There are more than just a few of us also that are a part of the OpenHPSDR effort that have evaluated the units (GPSDO) for over 1 year now (I have a project that is a bit overdue...but that is another story...) But, I haven't seen one single negative comment from anyone regarding these units. For the money - it is a good/great deal. I just bread-boarded the LC_XO I have for a test and it worked fine. I have one of those connector kits from Samtec and one of those breakout kits from FTDI, plus power supply - and that was it to get a nice evaluation going. I am working on a PCB this unit fits into - it is near completion - but that is for the HPSDR project. It will run standalone and on batteries. But, the board is 'feature-rich' and goes beyond just something to have the LC_XO on. 73's, John AJ6BC On Wed, Oct 30, 2013 at 6:11 PM, quartz55 quart...@hughes.net wrote: Is this JL LC_XO at around $300 going to supress the used Trimble/Zwhatever market price? I hope so. I think I would have put out the $ for this one rather than a 10 or more year old used piece of equipment. I still may do it. I just need to justify it somehow. Dave N3DT ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Surface Mount OCXO Questions
Hi You may have a good layout on your board, but they have to get the current to that pin / pad somehow. In all likelihood the amps of current through the pad it’s self are going to cause issues. Also remember that the ground is likely an RF return as well. Multiple rules and layout issues all collide at that pin….. Bob On Oct 30, 2013, at 9:02 PM, John C. Westmoreland, P.E. j...@westmorelandengineering.com wrote: Bob, OK - that makes sense. If you follow good analog/digital layout rules then this may not be a problem. But your point about the EFC sensitivity is well taken. But, that is always a problem. Yes, do a lot of people violate good analog/digital layout rules, especially on the ground planes - yep. This is exactly why I am asking these questions. Even in manufacturer's recommended layout instructions you can find mistakes. Unless you have a dev board that you have used and have the gerbers from that board so you know exactly how that part behaves with that layout - you cannot know for sure you have a sound layout for your design. You also have to be careful with board material, dielectrics, and copper weight, not to mention controlled impedances. Remember the early days of DC/DC converters? Thanks! John / AJ6BC On Wed, Oct 30, 2013 at 5:52 PM, Bob Camp li...@rtty.us wrote: Hi Consider that microvolts matter on the EFC. Unless you have a separate return for the oven current it’s going to be tough to keep everything separate. One might ask “why no separate return”. Well when you design one in, and then go look at people’s layouts - you might as well not have designed it in ….. Bob On Oct 30, 2013, at 8:37 PM, John C. Westmoreland, P.E. j...@westmorelandengineering.com wrote: Graham and Time Nuts, (thanks for the answers.) I have another question - I am looking at a part from MTI. I wanted to use one of their 3.3V parts. They are telling me to use the 12V part because the 3.3V part can have an issue with ground loops due to the higher current requirements at that voltage for the oven. Have any of you experienced this? Makes me wonder a little why they offer the 3.3V part. It would seem good layout can control any possibility of ground loops becoming a problem. Thanks and Regards, John W./AJ6BC On Wed, Oct 30, 2013 at 6:54 AM, Graham / KE9H time...@austin.rr.com wrote: John: All SMT OCXO's will either have a recommended PCB footprint in the spec sheet or will refer you to a recommended footprint in another document. Some don't care about a ground plane under the part, some require it with no crossing signals, some require an open thermal hole underneath the oven. I have seen all three cases. As usual, it is suggested that you read the [] manual. Best regards, --- Graham / KE9H == On 10/29/2013 9:18 PM, John C. Westmoreland, P.E. wrote: Hello, I was wondering if I could get some recommendations on surface mount OCXO's vs. the traditional through hole. I was also wondering on the board layout - if you found it necessary to leave a thermal moat so to speak - and what worked best. Maybe the OCXO has an internal air barrier that maybe would make this unnecessary - not sure. Your input and experience appreciated. Thanks, John Westmoreland __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nuts https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nuts https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO choices
Hi The Jackson Labs part has been around for a while. It seems to have no impact at all on the auction market prices for GPSDO’s. They seem to simply be driven by supply and demand for this or that very specific box. Even the availability of the NTBW parts at $135 has had no noticeable impact on the upward spiral in prices for the older equivalent parts. Bob On Oct 30, 2013, at 9:11 PM, quartz55 quart...@hughes.net wrote: Is this JL LC_XO at around $300 going to supress the used Trimble/Zwhatever market price? I hope so. I think I would have put out the $ for this one rather than a 10 or more year old used piece of equipment. I still may do it. I just need to justify it somehow. Dave N3DT ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Surface Mount OCXO Questions
John: Look at the ppm (or however they express it) as to the sensitivity of the frequency stability of the OCXO relative to Voltage input. Say the oven power drops from 3 watts to 1 Watt as the oven comes up to temperature. At 3 Volts, relative to 12 Volts, for a given resistance, it is four time the Voltage change due to the higher currents, and an additional four times the percentage of the operating Voltage as a ratio. So additional design consideration for Voltage control/stabilization is needed. If you have a solid (wide, thick, multi-layer) ground, then that can work. To reduce the voltage drop feeding the OCXO, you might consider putting a dedicated LDO regulator, right at the OCXO, that shares the ground reference with the OCXO, so any voltage drop in the feed side is removed, as well as any Voltage variability with current in the ground system. As to why they are selling the 3.3V part, they probably started selling it before they had some customers get into performance issues per the above. But once offered, they have to continue to support their customers. I think they are just telling you that it is somewhere between 4 and 16 times easier to get the full performance out of the part with a 12 Volt power feed than a 3 Volt power feed, not that you can't get full performance with a 3.3V feed. I am sure their parts meet specs, you just need to understand them. P.S. - I would stick with linear regulators feeding the OCXO, not a switcher. --- Graham == On 10/30/2013 7:37 PM, John C. Westmoreland, P.E. wrote: Graham and Time Nuts, (thanks for the answers.) I have another question - I am looking at a part from MTI. I wanted to use one of their 3.3V parts. They are telling me to use the 12V part because the 3.3V part can have an issue with ground loops due to the higher current requirements at that voltage for the oven. Have any of you experienced this? Makes me wonder a little why they offer the 3.3V part. It would seem good layout can control any possibility of ground loops becoming a problem. Thanks and Regards, John W./AJ6BC On Wed, Oct 30, 2013 at 6:54 AM, Graham / KE9H time...@austin.rr.comwrote: John: All SMT OCXO's will either have a recommended PCB footprint in the spec sheet or will refer you to a recommended footprint in another document. Some don't care about a ground plane under the part, some require it with no crossing signals, some require an open thermal hole underneath the oven. I have seen all three cases. As usual, it is suggested that you read the [] manual. Best regards, --- Graham / KE9H == On 10/29/2013 9:18 PM, John C. Westmoreland, P.E. wrote: Hello, I was wondering if I could get some recommendations on surface mount OCXO's vs. the traditional through hole. I was also wondering on the board layout - if you found it necessary to leave a thermal moat so to speak - and what worked best. Maybe the OCXO has an internal air barrier that maybe would make this unnecessary - not sure. Your input and experience appreciated. Thanks, John Westmoreland ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Surface Mount OCXO Questions
Graham, Good points - yes, I have this part currently in the design: TPS75833KTTT (LDO from TI) - putting another one down (just) for the OCXO isn't a problem. And a nice 12V rail isn't a problem either since this is for a radio with a nice 12V source. Could I boost the 3.3V rail to 12V or maybe 5V to 12V - sure - but your point about the switcher is well taken and I agree. Having a nice, fat, analog ground plane isn't a problem either. And, this is just a 'dev' board so we can do what we need to make the OCXO work as good as possible. From their spec sheet: '... the supply voltage sensitivity and load sensitivity is 5E-11 for a 5 % change in voltage or load impedance.' Thanks, John On Wed, Oct 30, 2013 at 6:47 PM, Graham / KE9H time...@austin.rr.comwrote: John: Look at the ppm (or however they express it) as to the sensitivity of the frequency stability of the OCXO relative to Voltage input. Say the oven power drops from 3 watts to 1 Watt as the oven comes up to temperature. At 3 Volts, relative to 12 Volts, for a given resistance, it is four time the Voltage change due to the higher currents, and an additional four times the percentage of the operating Voltage as a ratio. So additional design consideration for Voltage control/stabilization is needed. If you have a solid (wide, thick, multi-layer) ground, then that can work. To reduce the voltage drop feeding the OCXO, you might consider putting a dedicated LDO regulator, right at the OCXO, that shares the ground reference with the OCXO, so any voltage drop in the feed side is removed, as well as any Voltage variability with current in the ground system. As to why they are selling the 3.3V part, they probably started selling it before they had some customers get into performance issues per the above. But once offered, they have to continue to support their customers. I think they are just telling you that it is somewhere between 4 and 16 times easier to get the full performance out of the part with a 12 Volt power feed than a 3 Volt power feed, not that you can't get full performance with a 3.3V feed. I am sure their parts meet specs, you just need to understand them. P.S. - I would stick with linear regulators feeding the OCXO, not a switcher. --- Graham == On 10/30/2013 7:37 PM, John C. Westmoreland, P.E. wrote: Graham and Time Nuts, (thanks for the answers.) I have another question - I am looking at a part from MTI. I wanted to use one of their 3.3V parts. They are telling me to use the 12V part because the 3.3V part can have an issue with ground loops due to the higher current requirements at that voltage for the oven. Have any of you experienced this? Makes me wonder a little why they offer the 3.3V part. It would seem good layout can control any possibility of ground loops becoming a problem. Thanks and Regards, John W./AJ6BC On Wed, Oct 30, 2013 at 6:54 AM, Graham / KE9H time...@austin.rr.com wrote: John: All SMT OCXO's will either have a recommended PCB footprint in the spec sheet or will refer you to a recommended footprint in another document. Some don't care about a ground plane under the part, some require it with no crossing signals, some require an open thermal hole underneath the oven. I have seen all three cases. As usual, it is suggested that you read the [] manual. Best regards, --- Graham / KE9H == On 10/29/2013 9:18 PM, John C. Westmoreland, P.E. wrote: Hello, I was wondering if I could get some recommendations on surface mount OCXO's vs. the traditional through hole. I was also wondering on the board layout - if you found it necessary to leave a thermal moat so to speak - and what worked best. Maybe the OCXO has an internal air barrier that maybe would make this unnecessary - not sure. Your input and experience appreciated. Thanks, John Westmoreland __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
