[time-nuts] 32.768Khz Crystal/Resonator suggestions.
Hi all, I've got a project upcoming that will require a frequency of 32.768 Khz in a harsh environment (Imagine a thousand G's at 100Hz with 150 Deg C temperatures). Also, this thing needs to be small, 2mmx1.5x1.5mm or so. It also has to be low power. Frequency stability is probably less of a concern than just surviving (some frequency error vs. temp can be trimmed out with other smarts in the design. In the past, crystals just haven't liked surviving due to the construction. Have had good luck with ceramic resonators at higher frequencies (50Mhz and up). I've also looked at silicon oscillators, which will work in the application, however with the chip and associated resistors/caps they get a little bigger that what I was hoping for. Is anyone aware of a frequency source (crystal/resonator or other) in a small package that is robustly mounted? Or are there any ceramic resonators available that are in small packages in those low frequencies? I checked the big distributors, and did not have any luck. Dan ___ 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] 32.768Khz Crystal/Resonator suggestions.
Hi Dan, I beg your pardon for being so curious, but where do you have to put electronics in a thousand G's at 100Hz? Thank you Volker Am 01.11.2013 17:30, schrieb Dan Kemppainen: Hi all, I've got a project upcoming that will require a frequency of 32.768 Khz in a harsh environment (Imagine a thousand G's at 100Hz with 150 Deg C temperatures). Also, this thing needs to be small, 2mmx1.5x1.5mm or so. It also has to be low power. Frequency stability is probably less of a concern than just surviving (some frequency error vs. temp can be trimmed out with other smarts in the design. In the past, crystals just haven't liked surviving due to the construction. Have had good luck with ceramic resonators at higher frequencies (50Mhz and up). I've also looked at silicon oscillators, which will work in the application, however with the chip and associated resistors/caps they get a little bigger that what I was hoping for. Is anyone aware of a frequency source (crystal/resonator or other) in a small package that is robustly mounted? Or are there any ceramic resonators available that are in small packages in those low frequencies? I checked the big distributors, and did not have any luck. Dan ___ 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] wwvb d-psk-r updated general purpose reciever
When I was messing with my SkyScan WWVB clocks to determine if something that WWVB's signal had done broke them, preventing them from setting properly and so-doing, I wanted to see what the receiver module was seeing. (Spoiler: They didn't - they just break if the date is something later than approx. August, 2012 - I mentioned this some months ago on this list, providing a link to a blog entry where this was discussed in detail.) What I did to see what the clock chip was seeing via a 'scope was to hang a JFET source follower on the narrow (downstream) side of the 60.003 kHz bandpass filter crystal coupled with a small value cap and a with a 10 meg resistor from the gate to ground: That didn't seem to adversely affect performance, and I could see the phase flopping back and forth. (The signal was pretty low - but usable.) At that point the AM was still present, so the key up portions of the waveform were expectedly weaker - but it seemed to me at the time that I could have used it for something more complicated down the line. What I was thinking at the time, were I to proceed farther, would have been to take that buffered signal off-board, amplify it a bunch and then run it through a limiter. In theory, this - along with the demodulated time code - would have provided both the amplitude and phase components. Clint KA7OEI On Fri, 1 NOV 2013 saul swed said: Hello to the group. It has been a while since I have sent anything. The last was the wwvb regenerator for time clocks. However I have been working on a general purpose wwvb receiver. One that is inexpensive, uses parts available today, is inexpensive, single supply, low power, and uses parts I don't need a microscope for. There are lots of older designs out there and at least one quite nice design is by one of our fellow time-nuts that started me thinking. But many of the designs use inductors that have become difficult to obtain. As much as I would have loved to hack one of the one chip wwvb clock chip wonders they simply did not work out. They are hot receivers actually because there was no way to pull the amplified wwvb signal out. Tried a number of schemes like 2 chips in parallel. One detecting the AM signal and providing AGC control to chip 2 that had no AGC or demod caps. snip ___ 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] 32.768Khz Crystal/Resonator suggestions.
Kind of scratching my head on that also some blade? Regards Paul On Fri, Nov 1, 2013 at 5:50 PM, Volker Esper ail...@t-online.de wrote: Hi Dan, I beg your pardon for being so curious, but where do you have to put electronics in a thousand G's at 100Hz? Thank you Volker Am 01.11.2013 17:30, schrieb Dan Kemppainen: Hi all, I've got a project upcoming that will require a frequency of 32.768 Khz in a harsh environment (Imagine a thousand G's at 100Hz with 150 Deg C temperatures). Also, this thing needs to be small, 2mmx1.5x1.5mm or so. It also has to be low power. Frequency stability is probably less of a concern than just surviving (some frequency error vs. temp can be trimmed out with other smarts in the design. In the past, crystals just haven't liked surviving due to the construction. Have had good luck with ceramic resonators at higher frequencies (50Mhz and up). I've also looked at silicon oscillators, which will work in the application, however with the chip and associated resistors/caps they get a little bigger that what I was hoping for. Is anyone aware of a frequency source (crystal/resonator or other) in a small package that is robustly mounted? Or are there any ceramic resonators available that are in small packages in those low frequencies? I checked the big distributors, and did not have any luck. Dan ___ 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] wwvb d-psk-r updated general purpose reciever
Clint Like you I considered that and easy enough to do. But by that point you have built well over half the receiver. So I just said to heck with it and built the whole thing. The other issue is getting those pesky chips. There is one fellow time-nut that has a stash of CME chips he offered. Never heard that anyone accept me took him up on them. I built the regenerator with the cme and another with the 8160 chips just to insure they would both work for any time-nut that wanted to try. So by all means give it a shot isolate your new gain chain and use lots of limiting. The two I mention should deliver 50-70db worth. But the fact is the 3356 is at 50 db and the ad806 is no place close but sure puts out one nicely limited signal. I would believe simply a fet driving one of these chips would do the trick. Regards Paul. On Fri, Nov 1, 2013 at 6:06 PM, Clint Turner tur...@ussc.com wrote: When I was messing with my SkyScan WWVB clocks to determine if something that WWVB's signal had done broke them, preventing them from setting properly and so-doing, I wanted to see what the receiver module was seeing. (Spoiler: They didn't - they just break if the date is something later than approx. August, 2012 - I mentioned this some months ago on this list, providing a link to a blog entry where this was discussed in detail.) What I did to see what the clock chip was seeing via a 'scope was to hang a JFET source follower on the narrow (downstream) side of the 60.003 kHz bandpass filter crystal coupled with a small value cap and a with a 10 meg resistor from the gate to ground: That didn't seem to adversely affect performance, and I could see the phase flopping back and forth. (The signal was pretty low - but usable.) At that point the AM was still present, so the key up portions of the waveform were expectedly weaker - but it seemed to me at the time that I could have used it for something more complicated down the line. What I was thinking at the time, were I to proceed farther, would have been to take that buffered signal off-board, amplify it a bunch and then run it through a limiter. In theory, this - along with the demodulated time code - would have provided both the amplitude and phase components. Clint KA7OEI On Fri, 1 NOV 2013 saul swed said: Hello to the group. It has been a while since I have sent anything. The last was the wwvb regenerator for time clocks. However I have been working on a general purpose wwvb receiver. One that is inexpensive, uses parts available today, is inexpensive, single supply, low power, and uses parts I don't need a microscope for. There are lots of older designs out there and at least one quite nice design is by one of our fellow time-nuts that started me thinking. But many of the designs use inductors that have become difficult to obtain. As much as I would have loved to hack one of the one chip wwvb clock chip wonders they simply did not work out. They are hot receivers actually because there was no way to pull the amplified wwvb signal out. Tried a number of schemes like 2 chips in parallel. One detecting the AM signal and providing AGC control to chip 2 that had no AGC or demod caps. snip __**_ 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] 32.768Khz Crystal/Resonator suggestions.
Hi There are several possibilities, each of them pretty well tells you what industry is looking for the crystal. Bob On Nov 1, 2013, at 7:25 PM, paul swed paulsw...@gmail.com wrote: Kind of scratching my head on that also some blade? Regards Paul On Fri, Nov 1, 2013 at 5:50 PM, Volker Esper ail...@t-online.de wrote: Hi Dan, I beg your pardon for being so curious, but where do you have to put electronics in a thousand G's at 100Hz? Thank you Volker Am 01.11.2013 17:30, schrieb Dan Kemppainen: Hi all, I've got a project upcoming that will require a frequency of 32.768 Khz in a harsh environment (Imagine a thousand G's at 100Hz with 150 Deg C temperatures). Also, this thing needs to be small, 2mmx1.5x1.5mm or so. It also has to be low power. Frequency stability is probably less of a concern than just surviving (some frequency error vs. temp can be trimmed out with other smarts in the design. In the past, crystals just haven't liked surviving due to the construction. Have had good luck with ceramic resonators at higher frequencies (50Mhz and up). I've also looked at silicon oscillators, which will work in the application, however with the chip and associated resistors/caps they get a little bigger that what I was hoping for. Is anyone aware of a frequency source (crystal/resonator or other) in a small package that is robustly mounted? Or are there any ceramic resonators available that are in small packages in those low frequencies? I checked the big distributors, and did not have any luck. Dan ___ 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] The 5MHz Sweet Spot
A while ago I mentioned 5MHz oscillators were used in most metrology applications compared to the more commonly available 10MHz because 5MHz was a sweet spot for quartz. At the time I didn't know why. I finally had a chance to ask the person I learned this from why. The main reason is simply physical size. The larger crystal lattice allows many manufacturing advantages that allow for a higher Q. He also explained I was wrong in an earlier statement, metal/quartz migration on quartz oscillator was not a major problem even after decades, but could become more of a factor if driven hard. That does not mean the deposition and lead bonding has no negative effect. The BVA solves this by capacitive coupling the quartz rather then direct metal deposition. Thomas Knox ___ 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?
I do not have any say in it but I voiced the groups concerns to a few affiliates at NIST today. One Senior Researcher told me he has been making an effort for some time now to document all the equipment used related to a research project, adding the standard disclaimer that it was not an endorsement or recommendation. I tried to reach one of the papers author to see if they were comfortable releasing more GPS product data but missed him. I will try again Monday, but it is really up the authors what they feel comfortable with. I will also inquire as to what configuration of GPS they currently use for Time and Freq. Whether they use L1, or L1/L2, Carrier Phase or what the current thinking is of state of the art. Thomas Knox Date: Thu, 31 Oct 2013 00:33:28 +0100 From: mag...@rubidium.dyndns.org To: time-nuts@febo.com Subject: 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. ___ 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] The 5MHz Sweet Spot
Hi If you pick one holder, 5 MHz will be “best”. If you pick another holder, 2.5 MHz will be “best”. Pick another one and it will be 20 MHz …. Bob On Nov 1, 2013, at 10:12 PM, Tom Knox act...@hotmail.com wrote: A while ago I mentioned 5MHz oscillators were used in most metrology applications compared to the more commonly available 10MHz because 5MHz was a sweet spot for quartz. At the time I didn't know why. I finally had a chance to ask the person I learned this from why. The main reason is simply physical size. The larger crystal lattice allows many manufacturing advantages that allow for a higher Q. He also explained I was wrong in an earlier statement, metal/quartz migration on quartz oscillator was not a major problem even after decades, but could become more of a factor if driven hard. That does not mean the deposition and lead bonding has no negative effect. The BVA solves this by capacitive coupling the quartz rather then direct metal deposition. Thomas Knox ___ 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] The 5MHz Sweet Spot
On 11/1/2013 7:12 PM, Tom Knox wrote: A while ago I mentioned 5MHz oscillators were used in most metrology applications compared to the more commonly available 10MHz because 5MHz was a sweet spot for quartz. At the time I didn't know why. I finally had a chance to ask the person I learned this from why. The main reason is simply physical size. The larger crystal lattice allows many manufacturing advantages that allow for a higher Q. He also explained I was wrong in an earlier statement, metal/quartz migration on quartz oscillator was not a major problem even after decades, but could become more of a factor if driven hard. That does not mean the deposition and lead bonding has no negative effect. The BVA solves this by capacitive coupling the quartz rather then direct metal deposition. Thomas Knox A lot of issues conflated together here. 1. There is a theoretical QF product for quartz. Being at 5 MHz basically doubles your Q, all other things being equal. 2. Having a higher Q reduces the contribution of the sustaining amplifier, but only within the 3 dB bandwidth. With the Q being in the millions, this is only a few Hz. 3. In general, the sustaining amplifier is not a player in a well designed quartz oscillator in the first place. 4. Q probably has a negative correlation with flicker noise, meaning higher Q is associated with lower flicker noise. However, the correlation is not strong. There is no theory that says that Q puts a bound on flicker noise. 5. So that leaves us with the larger physical size. Perhaps it allows higher Q, but again it is unclear how this is connected with flicker noise. 6. You didn't mention the theory that more total atoms of quartz provides averaging flicker noise over a large population. 7. You didn't mention the notion that larger physical size permits higher drive level. Since the Q is also large, perhaps it doesn't. Also, a higher drive level is probably only going to help with far out noise. 8. Many, or maybe most, 5 MHz resonators are made with undersized blanks which are enabled by energy trapping. So we don't have a simple scaling of all 3 dimensions. What is the effect of this cheating? If someone can shed additional light on this, please jump in and educate us. Rick Karlquist N6RK ___ 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] The 5MHz Sweet Spot
HI If you doubled the diameter of the blank each time you cut the frequency in half, all sorts of nice things might happen. If you start with a 1/2” blank in at 10 MHz that goes to 1” at 5 MHz and 2” at 2.5 MHz. Around 1 MHz you would get to a 5” blank. Good luck finding high grade quartz bars to cut 5” (or even 1”) blanks out of. You are going to have to go back to the autoclave fixtures at the very least. Since growth is (at best) linear you cost of quartz will scale with the size of the blank. I’d bet it scales a bit more than that if you want to keep the material at a high level of performance. Then you need to cut it / lap it / polish it. All of that gear scales with blank size. That’s the easy part. Now you need to build a cold weld package that will accept your 5” blank. Then you need a proper press to seal it. The ones for the little blanks come in around $2-$3M each. First one you make (with all the back and forth) probably costs you 2X that to develop. Figure the cost will scale with the size of the package. That’s at least straightforward. Its just money. If you have a 5” blank, your OCXO scales around it. Yes you can do some neat things, but the package is getting bigger. You now need to convince people to buy OCXO’s that are bigger than anything they have seen since the 1960’s. In most cases that OCXO will be 2 to 10 times larger than their entire sub-system. That’s going to be a tough sell. No customers = no money to pay for all the fun stuff. Bob On Nov 1, 2013, at 10:56 PM, Richard (Rick) Karlquist rich...@karlquist.com wrote: On 11/1/2013 7:12 PM, Tom Knox wrote: A while ago I mentioned 5MHz oscillators were used in most metrology applications compared to the more commonly available 10MHz because 5MHz was a sweet spot for quartz. At the time I didn't know why. I finally had a chance to ask the person I learned this from why. The main reason is simply physical size. The larger crystal lattice allows many manufacturing advantages that allow for a higher Q. He also explained I was wrong in an earlier statement, metal/quartz migration on quartz oscillator was not a major problem even after decades, but could become more of a factor if driven hard. That does not mean the deposition and lead bonding has no negative effect. The BVA solves this by capacitive coupling the quartz rather then direct metal deposition. Thomas Knox A lot of issues conflated together here. 1. There is a theoretical QF product for quartz. Being at 5 MHz basically doubles your Q, all other things being equal. 2. Having a higher Q reduces the contribution of the sustaining amplifier, but only within the 3 dB bandwidth. With the Q being in the millions, this is only a few Hz. 3. In general, the sustaining amplifier is not a player in a well designed quartz oscillator in the first place. 4. Q probably has a negative correlation with flicker noise, meaning higher Q is associated with lower flicker noise. However, the correlation is not strong. There is no theory that says that Q puts a bound on flicker noise. 5. So that leaves us with the larger physical size. Perhaps it allows higher Q, but again it is unclear how this is connected with flicker noise. 6. You didn't mention the theory that more total atoms of quartz provides averaging flicker noise over a large population. 7. You didn't mention the notion that larger physical size permits higher drive level. Since the Q is also large, perhaps it doesn't. Also, a higher drive level is probably only going to help with far out noise. 8. Many, or maybe most, 5 MHz resonators are made with undersized blanks which are enabled by energy trapping. So we don't have a simple scaling of all 3 dimensions. What is the effect of this cheating? If someone can shed additional light on this, please jump in and educate us. Rick Karlquist N6RK ___ 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] The 5MHz Sweet Spot
On 11/1/2013 8:28 PM, Bob Camp wrote: HI If you doubled the diameter of the blank each time you cut the frequency in half, all sorts of nice things might happen. If you start with a 1/2” blank in at 10 MHz that goes to 1” at 5 MHz and 2” at 2.5 MHz. Around 1 MHz you would get to a 5” blank. Good luck finding high grade quartz bars to cut 5” (or even 1”) blanks out of. You are going to have to go back to the autoclave fixtures at the very least. Since growth is (at best) linear you cost of quartz will scale with the size of the blank. I’d bet it scales a bit more than that if you want to keep the material at a high level of performance. You've explained the excuses vendors give for not making full size crystals. But the question is, given these realities, does this reduce the theoretical advantage of the lower frequency and by how much? Rick Karlquist N6RK ___ 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] The 5MHz Sweet Spot
1. There is a theoretical QF product for quartz. Being at 5 MHz basically doubles your Q, all other things being equal. Doesn't that Q gain from the QF product go away if you have to PLL it up to 10 MHz or 100 MHz which is what you really want? [I was about to ask why not go to 1 MHz, but Bob Camp answered that already.] -- These are my opinions. I hate spam. ___ 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] The 5MHz Sweet Spot
If you have a 5” blank, your OCXO scales around it. Yes you can do some neat things, but the package is getting bigger. You now need to convince people to buy OCXO’s that are bigger than anything they have seen since the 1960’s. In most cases that OCXO will be 2 to 10 times larger than their entire sub-system. That’s going to be a tough sell. Does it become more susceptible to microphonics with larger blanks? Bob ___ 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] The 5MHz Sweet Spot
In a free running (non crystal controlled) oscillator, the oscillator with the highest Q (regardless of frequency) will have the best phase noise, if all oscillators are normallized to the same frequency by ideal multiplication. So the Q gain doesn't go away in that sense. Having said that, in crystal oscillators, Q doesn't determine noise in the first place, so the point is moot. Rick Karlquist N6RK On 11/1/2013 8:48 PM, Hal Murray wrote: 1. There is a theoretical QF product for quartz. Being at 5 MHz basically doubles your Q, all other things being equal. Doesn't that Q gain from the QF product go away if you have to PLL it up to 10 MHz or 100 MHz which is what you really want? [I was about to ask why not go to 1 MHz, but Bob Camp answered that already.] ___ 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] The 5MHz Sweet Spot
Hi The real answer is that nobody knows. The economics essentially make finding out very expensive. Q most certainly goes up, I don’t think anybody disputes that. The questions about flicker / ADEV all revolve around small blank parts with major edge sensitivity issues. They also probably were not running in a very good oven. Unless somebody with very deep pockets decides they need to find out, it’s going to be an un-answered question. Bob On Nov 1, 2013, at 11:41 PM, Richard (Rick) Karlquist rich...@karlquist.com wrote: On 11/1/2013 8:28 PM, Bob Camp wrote: HI If you doubled the diameter of the blank each time you cut the frequency in half, all sorts of nice things might happen. If you start with a 1/2” blank in at 10 MHz that goes to 1” at 5 MHz and 2” at 2.5 MHz. Around 1 MHz you would get to a 5” blank. Good luck finding high grade quartz bars to cut 5” (or even 1”) blanks out of. You are going to have to go back to the autoclave fixtures at the very least. Since growth is (at best) linear you cost of quartz will scale with the size of the blank. I’d bet it scales a bit more than that if you want to keep the material at a high level of performance. You've explained the excuses vendors give for not making full size crystals. But the question is, given these realities, does this reduce the theoretical advantage of the lower frequency and by how much? Rick Karlquist N6RK ___ 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] The 5MHz Sweet Spot
HI There’s no real reason why you would have more microphonic issues with a scaled larger blank. The bigger blank is likely to have a lower mechanical resonance (mount springs to blank mass) so it’s not going to be a star performer in vibration. Bob On Nov 1, 2013, at 11:50 PM, Bob Stewart b...@evoria.net wrote: If you have a 5” blank, your OCXO scales around it. Yes you can do some neat things, but the package is getting bigger. You now need to convince people to buy OCXO’s that are bigger than anything they have seen since the 1960’s. In most cases that OCXO will be 2 to 10 times larger than their entire sub-system. That’s going to be a tough sell. Does it become more susceptible to microphonics with larger blanks? Bob ___ 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] The 5MHz Sweet Spot
This all seems to be forgetting that the crystals are usually operated at 3rd or 5th harmonic. The crystal in a 10811A is 10 MHz/3rd overtone. A high quality 5 MHz/5th overtone crystal is really a 1 MHz fundamental, a large piece of quartz. Running at a harmonic greatly reduces the influence of the package. David On 11/2/13 1:07 AM, Bob Camp wrote: Hi The real answer is that nobody knows. The economics essentially make finding out very expensive. Q most certainly goes up, I don’t think anybody disputes that. The questions about flicker / ADEV all revolve around small blank parts with major edge sensitivity issues. They also probably were not running in a very good oven. Unless somebody with very deep pockets decides they need to find out, it’s going to be an un-answered question. Bob On Nov 1, 2013, at 11:41 PM, Richard (Rick) Karlquist rich...@karlquist.com wrote: On 11/1/2013 8:28 PM, Bob Camp wrote: HI If you doubled the diameter of the blank each time you cut the frequency in half, all sorts of nice things might happen. If you start with a 1/2” blank in at 10 MHz that goes to 1” at 5 MHz and 2” at 2.5 MHz. Around 1 MHz you would get to a 5” blank. Good luck finding high grade quartz bars to cut 5” (or even 1”) blanks out of. You are going to have to go back to the autoclave fixtures at the very least. Since growth is (at best) linear you cost of quartz will scale with the size of the blank. I’d bet it scales a bit more than that if you want to keep the material at a high level of performance. You've explained the excuses vendors give for not making full size crystals. But the question is, given these realities, does this reduce the theoretical advantage of the lower frequency and by how much? Rick Karlquist N6RK ___ 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.
