Re: [time-nuts] How far can I push a crystal?
Hi Ed, Thanks, your explanation of single PLL helps. I see it now somewhat in the sense of only have to BUILD a single PLL to make things work. I can appreciate the simplified effort greatly. I also now think of the PLO as an oscillator locked to a tuned harmonic that (probably) comes from some sort of comb generator, so that's not a PLL in the more conventional sense, and the resulting system becomes a true single PLL design. I'll look forward to hearing how it works out. Bob L. - Original Message From: Ed Breya e...@telight.com To: time-nuts@febo.com Sent: Tue, January 22, 2013 11:46:35 PM Subject: Re: [time-nuts] How far can I push a crystal? I tried to send this message on Sunday, but for some reason it didn't go through, so here it is again. Please excuse any redundancy if the original shows up. I will have an update of the project soon. Hi Bob L., Your suggestion of the 300/953 scheme was inspiration for what hopefully will be the simplest solution of all - I've started building it. First, I should clarify more, that the original scheme actually has three phase-locked loops - a 10.7 MHz, a 10.0594 MHz, and the final one, 1207.133 MHz. The last one is a PLO brick that just multiplies any RF input by any n within reason to phase lock the microwave output (to nth harmonic of input). I wasn't counting that one, since it's more or less a fixed function, but it's a variable (arbitrary n) in the numbers game. So, when I was referring to getting rid of one PLL, I meant not needing to produce the intermediate 10.7 MHz, since the 953 gives a rational number solution directly from 1 or 10 MHz - this is the single PLL scenario. I tested the PLO and microwave section with 15.88333 MHz = (10 MHz/600)*953 from a synthesizer, and it worked just fine. The PLO is tuned near 1207 MHz, and uses whatever n lands it within lock range, so n=76 in this case. If you adjust the cavity, n can just as easily be 75 or 77, with different output frequencies, or a number of numbers that satisfy the bounds of operation. So, the trick is to produce that one correct frequency from the 10 MHz reference, cleanly enough to get the job done, and feed it to the PLO - the n value takes care of itself. The way it's partitioned now, I will have one can containing the 15.883 MHz VCXO (74HC86 and a 16 MHz ceramic resonator), two LAN LPFs, a 74HC4020 feedback divider (1/953), and a CD4046B PLL. A second can, which is needed anyway for handling the various external and internal 10 and 1 MHz references, will not only route and scale, but will also include the divider to make the 16.6 kHz (10 MHz/600) reference for the other box. So, the overall synthesis chain is (10 MHz/600)*953*76=1207.13 MHz. Pretty simple. Ed ___ 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] How far can I push a crystal?
I tried to send this message on Sunday, but for some reason it didn't go through, so here it is again. Please excuse any redundancy if the original shows up. I will have an update of the project soon. Hi Bob L., Your suggestion of the 300/953 scheme was inspiration for what hopefully will be the simplest solution of all - I've started building it. First, I should clarify more, that the original scheme actually has three phase-locked loops - a 10.7 MHz, a 10.0594 MHz, and the final one, 1207.133 MHz. The last one is a PLO brick that just multiplies any RF input by any n within reason to phase lock the microwave output (to nth harmonic of input). I wasn't counting that one, since it's more or less a fixed function, but it's a variable (arbitrary n) in the numbers game. So, when I was referring to getting rid of one PLL, I meant not needing to produce the intermediate 10.7 MHz, since the 953 gives a rational number solution directly from 1 or 10 MHz - this is the single PLL scenario. I tested the PLO and microwave section with 15.88333 MHz = (10 MHz/600)*953 from a synthesizer, and it worked just fine. The PLO is tuned near 1207 MHz, and uses whatever n lands it within lock range, so n=76 in this case. If you adjust the cavity, n can just as easily be 75 or 77, with different output frequencies, or a number of numbers that satisfy the bounds of operation. So, the trick is to produce that one correct frequency from the 10 MHz reference, cleanly enough to get the job done, and feed it to the PLO - the n value takes care of itself. The way it's partitioned now, I will have one can containing the 15.883 MHz VCXO (74HC86 and a 16 MHz ceramic resonator), two LAN LPFs, a 74HC4020 feedback divider (1/953), and a CD4046B PLL. A second can, which is needed anyway for handling the various external and internal 10 and 1 MHz references, will not only route and scale, but will also include the divider to make the 16.6 kHz (10 MHz/600) reference for the other box. So, the overall synthesis chain is (10 MHz/600)*953*76=1207.13 MHz. Pretty simple. Ed ___ 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] How far can I push a crystal?
Ed, busy weekend happening, delayed my response. Bob Camp's reply regarding the DFF was spot on, and your connections below are just what to do. When feeding a DFF with non-synchronous signals it's likely setup and hold times will be violated. When that happens oscillation is possible, but usually dies out fairly quickly so that setup and hold times are met for the second DFF. The second DFF is thus much less likely to exhibit an incorrect output condition. I'm not sure about a single-PLL approach, thinking of multiplications of 953 and 38 as two steps, and thus two PLLs. If you can multiply by 36214 (to 1207.133MHz) in a single step I'd like to know more about your approach. In general I feel uncomfortable with such a high multiplication factor, just because of the time lag through the long divider. Since I'm no PLL expert I may be totally wrong, so any comments made by you or others will improve my knowledge base. I had forgotten your earlier email about the previous noisy attempt, sorry my oscillator comment was redundant. And thanks for the background on the 10.7MHz starting point. Regarding coming up with a set of numbers for a single PLL approach I find a spreadsheet and the two online calculators (decimal to fraction, and factoring) make for easier work. But it will be up to you to decide what scheme best fits your needs. Good luck with the project! Bob L. - Original Message From: Ed Breya e...@telight.com To: time-nuts@febo.com Sent: Fri, January 18, 2013 5:13:00 PM Subject: Re: [time-nuts] How far can I push a crystal? Bob, please tell me more about cascading the DFFs. I was only using one half of the '74, with the other inactive, so both are available for the task. From your description it sounds like I just run the Q from the first DFF to the D of the second, clock them together from the 1 or 10 MHz, and take the cleaned up difference signal from the Q of the second. So, I think what it means is that the same information should pass through, just delayed by one sampling clock cycle, and scrubbed of any edge uncertainty of an analog nature, that would otherwise be passed to the phase detector. Right? I would definitely do this if no additional logic packages are required. If a single-PLL type we discussed earlier is workable, I won't even need to worry about the second PLL system. It all depends on whether the phase detector frequency will be high enough. I'll be thinking through that and trying a few experiments. It's simple enough that I could even just build it and see what happens. If it's not right, then I'll just go with the previous plan, with high confidence - and a two-stage sampler. Regarding the oscillators - yes, having different signals present in common packages is what got me into this trouble in the first place. As I mentioned earlier, I had optimized the original design for compactness and minimum package count, so I had every signal in the box going every which way, all mixed up. I had used a different method for making the 10.7 MHz though - building it up by mixing various divided frequencies, then filtering it with cascaded 10.7 MHz IF filters. Most of the stuff went right around the filters anyway, since there was so much whizzing around in there. In case anyone is wondering why I'm so hung up on this 10.7 MHz thing: For this particular tracking generator project, I just need to synthesize one fixed, correct reference frequency with the simplest, most compact scheme that performs well enough. The original design evolved from using the 10.7 MHz base frequency, but it isn't actually needed per se. If anyone comes up with sets of numbers that seem to work in a single-PLL scheme, and fit the constraints evident in this discussion, please let me know. I have other tracking generator projects in the works though, that will cover most or all of the 8566B span of ~0 to 24 GHz, and need to produce various numeric and harmonic relationships for IFs and frequency control - all of these can be readily integer-derived from the fundamental 10 and 10.7 MHz references. In all cases, the ultimate reference is the 10 MHz used or produced by the 8566B, so everything is phase locked. Ed ___ 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] How far can I push a crystal?
Hi Just to complete the thread: You can take the inductor that resonates out C0 one more step. If you break (or tap) the inductor it can act as a transformer. The impedance transformation lets you swing the oscillator further with a specific amount of variap change in capacitance. Resonating out C0 does indeed let you swing above the anti resonant point on the crystal. It also eliminates the linearity issues associated with C0. All that said, The stability / jitter / phase noise / ADEV of a wide band VCXO is not going to be TimeNuts compatible. Bob On Jan 17, 2013, at 11:50 PM, Rick Karlquist rich...@karlquist.com wrote: Bernd Neubig wrote: A parallel inductor for compensation of the static capacitance C0 does not help much at 10 MHz, because such a coil, which resonates out a 6 pF capacitance has an internal winding capacitance, which is larger than 6 pF. So you would need a coil which has a self-resonance of slightly above 10 MHz. Actually, a parallel inductor helps a lot and is essential for getting a large pulling range. Modern surface mount coils have a self capacitance of a fraction of a pF, not 6 pF, and in any event, you can always find an inductor that is resonant when combined with the crystal. The nominal value of this inductor may be considerably less than the calculated value, but there is always some value of inductor that works. This was true even in the through hole era. 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] How far can I push a crystal?
Ed, Please forgive me for commenting, but I can't seem to follow your math. I suspect there may be additional details you have not related, no big deal there. It doesn't help that I'm not familiar with the 8566B, and the manual I grabbed from Didier's site doesn't give me numbers that match up with yours, so I'll just present my understanding based on your supplied numbers. To look at what you were doing more concisely I did a quick spreadsheet, and came up with this: 10 MHz div by 100 0.1 MHz mult by 107 10.7 MHz div by 180 0.059 MHz mult by 169.224299 10.059 MHz mult by 120 1207.1 MHz mult by 3 3621.4 MHz So I'm not sure how you get from 59.KHz to 10.059MHz by a PLL unless you have a really good fractional scheme to do the 169.224299 multiplication. (The fractional part .224299 ~= 64082 / 258699 so it is a bit ugly to do.) Or are you mixing the 59.KHz with 10MHz and using the sum only? I'd think that would be difficult given that the difference frequency is not that far from the desired output. Being the nut that I am I looked at some other ways to get from here to there, ending up with a simpler multiply-divide scheme like this: 10 MHz div by 300 0.0 MHz mult by 953 31.7667 MHz mult by 38 1207.13 MHz mult by 3 3621.40 MHz Unfortunately the intermediate 31.7MHz is not commonly available in a crystal or VCXO, and too far to pull a 32MHz part, so a custom crystal would be needed. respectfully, Bob LaJeunesse p.s. Should you find it useful I've attached the spreadsheet I used. - Original Message From: Ed Breya e...@telight.com To: time-nuts@febo.com Sent: Fri, January 18, 2013 1:34:19 AM Subject: Re: [time-nuts] How far can I push a crystal? ... For the curious: The 10.059... MHz is made by a PLL using the 59.... kHz reference, which is 10.7 MHz divided by 180. The 10.7 MHz is a from another VCXO (which can use a standard crystal, ceramic resonator, or ceramic IF filter - easy) that's phase locked to a 10 or 1 MHz reference, using two fixed dividers. The 10.059... MHz is used as the reference for a phase locked microwave brick oscillator, using n=120, to make 1207.1333... MHz, which is exactly one-third of 3621.4 MHz, the low-band upconversion IF of the HP8566B spectrum analyzer. The 1207.1333... MHz is harmonically mixed (m=3) with the first LO of the SA to produce the tracking signal centered in the passband of the SA. All of this is built into the modified carcass of an HP8443A tracking generator, originally built for older SA models. Using the new stuff, plus parts of the 8443A, the net result is a 50 kHz to 250 MHz tracking generator, with power up to +10 dBm, leveled within about 1 dB, and with 130 dB step attenuator range - very nice for low RF and baseband work. ... Ed Tracking_Generator_Scheme.xls Description: application/excel ___ 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] How far can I push a crystal?
Hi If you are going to multiply this up to microwaves, you may have some issues with phase noise Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Ed Breya Sent: Friday, January 18, 2013 1:33 AM To: time-nuts@febo.com Subject: Re: [time-nuts] How far can I push a crystal? Thanks all, for the feedback on this issue. In summary, I got these points out of the discussion on crystals: 1. The correct terminology is pulling the frequency. 2. Getting beyond about a few hundred ppm from the nominal frequency ranges from very difficult to pointless. 3. It's easier to pull down than up. It looks like it would not be worth fooling around with crystals, so I'll just use the ceramic resonators. By the way, I just tonight managed to reach the correct geological layer of stuff out in the garage, and found the missing 10 MHz resonators, and a whole tray of other parts that were in reserve for completing this project from a couple of years ago. For the curious: The 10.059... MHz is made by a PLL using the 59.... kHz reference, which is 10.7 MHz divided by 180. The 10.7 MHz is a from another VCXO (which can use a standard crystal, ceramic resonator, or ceramic IF filter - easy) that's phase locked to a 10 or 1 MHz reference, using two fixed dividers. The 10.059... MHz is used as the reference for a phase locked microwave brick oscillator, using n=120, to make 1207.1333... MHz, which is exactly one-third of 3621.4 MHz, the low-band upconversion IF of the HP8566B spectrum analyzer. The 1207.1333... MHz is harmonically mixed (m=3) with the first LO of the SA to produce the tracking signal centered in the passband of the SA. All of this is built into the modified carcass of an HP8443A tracking generator, originally built for older SA models. Using the new stuff, plus parts of the 8443A, the net result is a 50 kHz to 250 MHz tracking generator, with power up to +10 dBm, leveled within about 1 dB, and with 130 dB step attenuator range - very nice for low RF and baseband work. The 10.059... MHz is only one of many frequencies that could be multiplied by various n-values to give the same result, but it was chosen because it was very close to a standard frequency available in ceramic resonators, high enough that n didn't need to be too large, and it could be synthesized with a very simple PLL system. I had all of this built and running, but I had made the fatal engineering mistake of putting way too much stuff in too small a space. Space was tight, so I squeezed the entire LF control system and synthesizers into one small can, and necessarily optimized for minimum IC package count. Then I found that there was too much crosstalk between virtually all the signals in the box, so there was too much phase noise to work at 300 Hz and less IFBW. The problems were irreversible - sharing IC packages for multiple signal processing was an especially bad move. After many hours of rearranging signal paths, adding shielding and grounds, and changing topologies, I concluded that I had to rebuild it the right way. So here I am. The two main frequencies will be generated in separate boxes, and no ICs will contain multiple signals that aren't being processed together. This time I'll get it right, and finally wrap it up. Ed ___ 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] How far can I push a crystal?
Yes Robert, the 59. kHz is effectively added to the 10. MHz, but not by direct mixing. The 1 or 10 MHz reference drives a D-flop flop, which samples the 10.059444 MHz, leaving the difference frequency 59. kHz, the feedback signal in the second PLL. The direct way to do it would be with very accurate, full I-Q mixing to get only one sideband, but that gets very complicated. The current scheme is simpler, and works quite well. The main pieces are decade dividers (74HC390), dividers for 107 and 180 (74HC393 or 74HC4040 each), a D-FF (74HC74), a CD4046B for each PLL, and gates for the oscillators (74HC04 or 74HC86). Using an '86 allows for getting push-pull output with equal prop delays, in case I need to run it through some differential LAN LPF modules that I have on hand. It took some effort to come up with workable numbers that all fit within the constraints, but I'm sure there are many other undiscovered sets that would do it. I like your single-PLL 300/953 idea - it may be doable within 74HC speeds, and I think ceramic resonators are available at 32.0 MHz. The PLO would like the much higher reference frequency - I think any n from 8 to 150 or so will work. Scaling that by two to 600/953 , making 15.88333 MHz, with a 16 MHz resonator (I have some), fc=16. kHz, and n=76 should work too. It would be OK with 74HC for sure, and it would just fit through the LPFs, which cut off at 17 MHz. The comparison frequency fc is getting kind of low, but may be OK, depending on how much near-in phase noise I have to contend with. That was one of the reasons I opted for the two-stage approach - to avoid having a very small fc, or dealing with fractional-n ripple. I will investigate these possibilities and put together some experiments. I can directly drive the microwave section from an external synthesizer to try various reference frequencies. Ed ___ 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] How far can I push a crystal?
Ed, A DUH! (i.e. why didn't I see it) moment. I'm too used to thinking with an analog RF hat when I follow Time Nuts. The DFF mix-down makes perfect sense, and clarifies to me some key points of your design. I would hope that for the down-mixer you are using two DFFs cascaded with the same clock to both. This guarantees that any metastability in the first will likely settle out before the second one gets clocked on the next cycle. Otherwise there may be some undesirable noise injected into / through the 4046 phase comparator. Since you intend to use gates for oscillators be extra careful about using only one oscillator per chip, with the chip supply well isolated and bypassed tightly. Since logic parts are not designed for time nut supply noise immunity they can talk to each other quite well via their power and ground pins. Adding a small (33 Ohm or so) series resistor at any output driving a longer trace also helps reduce noisy fast edges and supply noise spikes. Good luck with the project. Bob L. - Original Message From: Ed Breya e...@telight.com To: time-nuts@febo.com Sent: Fri, January 18, 2013 1:39:00 PM Subject: Re: [time-nuts] How far can I push a crystal? Yes Robert, the 59. kHz is effectively added to the 10. MHz, but not by direct mixing. The 1 or 10 MHz reference drives a D-flop flop, which samples the 10.059444 MHz, leaving the difference frequency 59. kHz, the feedback signal in the second PLL. The direct way to do it would be with very accurate, full I-Q mixing to get only one sideband, but that gets very complicated. The current scheme is simpler, and works quite well. The main pieces are decade dividers (74HC390), dividers for 107 and 180 (74HC393 or 74HC4040 each), a D-FF (74HC74), a CD4046B for each PLL, and gates for the oscillators (74HC04 or 74HC86). Using an '86 allows for getting push-pull output with equal prop delays, in case I need to run it through some differential LAN LPF modules that I have on hand. It took some effort to come up with workable numbers that all fit within the constraints, but I'm sure there are many other undiscovered sets that would do it. I like your single-PLL 300/953 idea - it may be doable within 74HC speeds, and I think ceramic resonators are available at 32.0 MHz. The PLO would like the much higher reference frequency - I think any n from 8 to 150 or so will work. Scaling that by two to 600/953 , making 15.88333 MHz, with a 16 MHz resonator (I have some), fc=16. kHz, and n=76 should work too. It would be OK with 74HC for sure, and it would just fit through the LPFs, which cut off at 17 MHz. The comparison frequency fc is getting kind of low, but may be OK, depending on how much near-in phase noise I have to contend with. That was one of the reasons I opted for the two-stage approach - to avoid having a very small fc, or dealing with fractional-n ripple. I will investigate these possibilities and put together some experiments. I can directly drive the microwave section from an external synthesizer to try various reference frequencies. Ed ___ 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] How far can I push a crystal?
10.059 used to be a standard frequency for some 8051 microcontrollers. Should not be too hard to find. Didier Sent from my Droid Razr 4G LTE wireless tracker. -Original Message- From: Ed Breya e...@telight.com To: time-nuts@febo.com Sent: Thu, 17 Jan 2013 7:11 PM Subject: Re: [time-nuts] How far can I push a crystal? Bob, are you saying they have 10.059 MHz crystals? I've never seen one anywhere, or anything even close. Ed Hi Mouser shows 16 items tighter than +/- 20 ppm accuracy. Six of them are in stock and less than $1 in single piece quantities. The cheapest is 39 cents. 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] How far can I push a crystal?
About $4 on epay will get you a DDS knurdle with crystal reference that'll deliver... Rick Karlquist Ed Breya wrote: Maybe I should clarify what I meant by pushing the crystal frequency. I meant only using various topologies and electronic components in the associated circuitry, that would detune it from its natural resonance far enough to reach the new frequency, and still have it be sort of a narrow-bandwidth crystal oscillator - not doing any mechanical changes to the crystal element itself. Since the ceramic resonators seem to work well, and can be pushed (or pulled?) fairly far away by proper selection of the associated component values, I was wondering how far quartz crystals can reasonably go. I Since you asked: You can get something like a range of 0.1% by resonating out the holder capacitance with a shunt inductor. You then put this assembly in series with an inductor and varactor. If you want to get into the lunatic fringe, you use a high Q inductor wound on Fair-Rite 61 or 67. Now you can seriously pull the crystal below its resonant frequency. How far you can go depends on the Q of the inductor. I am not sure if you can also pull it above, but even if you could, there are spurious resonances up there that could get you. The lunatic fringe might get you .2 or .3%, still not .6%. You'll definitely take a hit in temperature stability and phase noise with high pulling. If you don't have experience with VCXO's, you will find the circuit design quite challenging. It wasn't clear if you needed a 10.05944 MHz VCXO, or just a source at that frequency. There a lots of one chip synthesizers that could generate that frequency as I'm sure you know. 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. -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. De Erroribus Medicorum, R. Bacon, 13th century. If you don't know what it is, don't poke it. Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com ___ 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] How far can I push a crystal?
Bob, please tell me more about cascading the DFFs. I was only using one half of the '74, with the other inactive, so both are available for the task. From your description it sounds like I just run the Q from the first DFF to the D of the second, clock them together from the 1 or 10 MHz, and take the cleaned up difference signal from the Q of the second. So, I think what it means is that the same information should pass through, just delayed by one sampling clock cycle, and scrubbed of any edge uncertainty of an analog nature, that would otherwise be passed to the phase detector. Right? I would definitely do this if no additional logic packages are required. If a single-PLL type we discussed earlier is workable, I won't even need to worry about the second PLL system. It all depends on whether the phase detector frequency will be high enough. I'll be thinking through that and trying a few experiments. It's simple enough that I could even just build it and see what happens. If it's not right, then I'll just go with the previous plan, with high confidence - and a two-stage sampler. Regarding the oscillators - yes, having different signals present in common packages is what got me into this trouble in the first place. As I mentioned earlier, I had optimized the original design for compactness and minimum package count, so I had every signal in the box going every which way, all mixed up. I had used a different method for making the 10.7 MHz though - building it up by mixing various divided frequencies, then filtering it with cascaded 10.7 MHz IF filters. Most of the stuff went right around the filters anyway, since there was so much whizzing around in there. In case anyone is wondering why I'm so hung up on this 10.7 MHz thing: For this particular tracking generator project, I just need to synthesize one fixed, correct reference frequency with the simplest, most compact scheme that performs well enough. The original design evolved from using the 10.7 MHz base frequency, but it isn't actually needed per se. If anyone comes up with sets of numbers that seem to work in a single-PLL scheme, and fit the constraints evident in this discussion, please let me know. I have other tracking generator projects in the works though, that will cover most or all of the 8566B span of ~0 to 24 GHz, and need to produce various numeric and harmonic relationships for IFs and frequency control - all of these can be readily integer-derived from the fundamental 10 and 10.7 MHz references. In all cases, the ultimate reference is the 10 MHz used or produced by the 8566B, so everything is phase locked. Ed ___ 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] How far can I push a crystal?
On 18.01.2013 22:41, shali...@gmail.com wrote: 10.059 used to be a standard frequency for some 8051 microcontrollers. Should not be too hard to find. No, it was 11.0592 Regards, Javier ___ 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] How far can I push a crystal?
HI Different Bob, but here's the flip flop answer On Jan 18, 2013, at 5:11 PM, Ed Breya e...@telight.com wrote: Bob, please tell me more about cascading the DFFs. I was only using one half of the '74, with the other inactive, so both are available for the task. From your description it sounds like I just run the Q from the first DFF to the D of the second, clock them together from the 1 or 10 MHz, and take the cleaned up difference signal from the Q of the second. So, I think what it means is that the same information should pass through, just delayed by one sampling clock cycle, and scrubbed of any edge uncertainty of an analog nature, that would otherwise be passed to the phase detector. Right? I would definitely do this if no additional logic packages are required. The gotcha with any flip flop is that it can get confused if you hit it just wrong. Exactly what constitutes wrong varies a bit depending on what kind of flip flop it is. In the case of a D flip flop with an edge sensitive clock, wrong is the data and clock changing at just about the same time. There is a possibility that the flip flop goes into oscillation rather than latching to either a 1 or a 0 state. If there's enough gain, it can keep on going until the next clock edge comes along. Obviously, this isn't what you want it to do. By cascading flip flops, you have much less chance of things hitting the final flip flop and creating an oscillator. Bob If a single-PLL type we discussed earlier is workable, I won't even need to worry about the second PLL system. It all depends on whether the phase detector frequency will be high enough. I'll be thinking through that and trying a few experiments. It's simple enough that I could even just build it and see what happens. If it's not right, then I'll just go with the previous plan, with high confidence - and a two-stage sampler. Regarding the oscillators - yes, having different signals present in common packages is what got me into this trouble in the first place. As I mentioned earlier, I had optimized the original design for compactness and minimum package count, so I had every signal in the box going every which way, all mixed up. I had used a different method for making the 10.7 MHz though - building it up by mixing various divided frequencies, then filtering it with cascaded 10.7 MHz IF filters. Most of the stuff went right around the filters anyway, since there was so much whizzing around in there. In case anyone is wondering why I'm so hung up on this 10.7 MHz thing: For this particular tracking generator project, I just need to synthesize one fixed, correct reference frequency with the simplest, most compact scheme that performs well enough. The original design evolved from using the 10.7 MHz base frequency, but it isn't actually needed per se. If anyone comes up with sets of numbers that seem to work in a single-PLL scheme, and fit the constraints evident in this discussion, please let me know. I have other tracking generator projects in the works though, that will cover most or all of the 8566B span of ~0 to 24 GHz, and need to produce various numeric and harmonic relationships for IFs and frequency control - all of these can be readily integer-derived from the fundamental 10 and 10.7 MHz references. In all cases, the ultimate reference is the 10 MHz used or produced by the 8566B, so everything is phase locked. Ed ___ 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] How far can I push a crystal?
I've got to make a very clean 10.0594... MHz VCXO for a redo of one of my old circuits. I previously used a 10 MHz ceramic resonator, which was easy enough to push around in frequency. Of course, I have a couple dozen of those somewhere, but can't find them now that I need them again. I figured I'd just pull the ones out of the old circuit, but since I did find a whole bunch of 10 MHz quartz crystals, I'd like to revisit whether I can push one of those that far with decent results. As I recall, the results of my previous experiments in doing this were less than satisfactory, which is why I went with the ceramics. This would be a change of 60 kHz out of 10 MHz, or 0.6 percent - a helluva lot for a crystal. The frequency will be exactly phase locked to a reference. It doesn't need to have extremely high in-circuit Q or long-term stability - just tunable to that magic number - the PLL will do the rest. A conventional varicap circuit will provide the VCO-ness, while the tuning range just needs to be enough to accommodate drift and the initial setting. The power gain element will be a 74HC04 or 74HC86 section. The PLL reference will be 59.4... kHz - way above the necessary loop BW. Has anyone successfully pushed a quartz crystal that far off, with reliable (still sort of a sharp resonance) operation and no spurious modes? Any ideas? If this isn't practical, I'll just go back to the ceramic resonator (which worked just fine), but I'd like to settle it once and for all. Ed ___ 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] How far can I push a crystal?
Ed Breya wrote: I've got to make a very clean 10.0594... MHz VCXO for a redo of one of my old circuits. I previously used a 10 MHz ceramic resonator, which Forget about it. This is well beyond even the lunatic fringe of pulling. Rick ___ 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] How far can I push a crystal?
You'll never pull a crystal that far without grinding :). Regards, Tom - Original Message - From: Ed Breya e...@telight.com To: time-nuts@febo.com Sent: Thursday, January 17, 2013 6:38 PM Subject: [time-nuts] How far can I push a crystal? I've got to make a very clean 10.0594... MHz VCXO for a redo of one of my old circuits. I previously used a 10 MHz ceramic resonator, which was easy enough to push around in frequency. Of course, I have a couple dozen of those somewhere, but can't find them now that I need them again. I figured I'd just pull the ones out of the old circuit, but since I did find a whole bunch of 10 MHz quartz crystals, I'd like to revisit whether I can push one of those that far with decent results. As I recall, the results of my previous experiments in doing this were less than satisfactory, which is why I went with the ceramics. This would be a change of 60 kHz out of 10 MHz, or 0.6 percent - a helluva lot for a crystal. The frequency will be exactly phase locked to a reference. It doesn't need to have extremely high in-circuit Q or long-term stability - just tunable to that magic number - the PLL will do the rest. A conventional varicap circuit will provide the VCO-ness, while the tuning range just needs to be enough to accommodate drift and the initial setting. The power gain element will be a 74HC04 or 74HC86 section. The PLL reference will be 59.4... kHz - way above the necessary loop BW. Has anyone successfully pushed a quartz crystal that far off, with reliable (still sort of a sharp resonance) operation and no spurious modes? Any ideas? If this isn't practical, I'll just go back to the ceramic resonator (which worked just fine), but I'd like to settle it once and for all. Ed ___ 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] How far can I push a crystal?
Forget about it. This is well beyond even the lunatic fringe of pulling. So how far can I pull a crystal? Does it depend upon the cut or anything that turns into price? -- 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] How far can I push a crystal?
My friend Karl-Heinz DJ7NN has dragged/jerked/teared/wrenched crystals even more (what is the most nasty description of pulling a quartz crystal?) - if need be, he opens it and strikes a brush over it to carefully grind some material, what makes it oscillating a little faster. If you've ground too much, make a stroke with a pencil on it and it will oscillate slower. But the aging... Ok, the drawback is, you won't get a very clean signal... In my humble opinion, as Ed told before: forget about it. Volker Am 18.01.2013 00:59, schrieb Rick Karlquist: Ed Breya wrote: I've got to make a very clean 10.0594... MHz VCXO for a redo of one of my old circuits. I previously used a 10 MHz ceramic resonator, which Forget about it. This is well beyond even the lunatic fringe of pulling. Rick ___ 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] How far can I push a crystal?
If you need a very clean signal - what would mean, stable (and accurate) you'll have to purchase one. There are manufacturers that do the job for, say, 30 Dollars? if it is a normal cut. If you like to get a crystal for a specific temperature to build your own oven (to achieve a very stable frequency) you can use an SC-cut - what is propably much more expensive. Volker Am 18.01.2013 01:16, schrieb Hal Murray: Forget about it. This is well beyond even the lunatic fringe of pulling. So how far can I pull a crystal? Does it depend upon the cut or anything that turns into price? ___ 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] How far can I push a crystal?
Hi You can always use a crystal as a capacitor in just about any oscillator circuit. The question becomes at what point does it stop doing anything other than behave like a capacitor. The accurate way to figure this out is to know the motional capacitance of the crystal. From that and the C0 you can do some modeling and see what you get. More simple answer - anything past about 0.1% is a bit silly even with an easy to pull crystal. If you have very modest goals, 0.3 or 0.4% is possible. If your goals are modest, a VCO might also do just as well. Bob On Jan 17, 2013, at 7:16 PM, Hal Murray hmur...@megapathdsl.net wrote: Forget about it. This is well beyond even the lunatic fringe of pulling. So how far can I pull a crystal? Does it depend upon the cut or anything that turns into price? -- 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. ___ 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] How far can I push a crystal?
Here an example manufactorer in my country: http://www.quarztechnik.com/eng/hochfrequentequarze.html or http://www.icmfg.com/ Am 18.01.2013 01:31, schrieb Volker Esper: If you need a very clean signal - what would mean, stable (and accurate) you'll have to purchase one. There are manufacturers that do the job for, say, 30 Dollars? if it is a normal cut. If you like to get a crystal for a specific temperature to build your own oven (to achieve a very stable frequency) you can use an SC-cut - what is propably much more expensive. Volker Am 18.01.2013 01:16, schrieb Hal Murray: Forget about it. This is well beyond even the lunatic fringe of pulling. So how far can I pull a crystal? Does it depend upon the cut or anything that turns into price? ___ 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] How far can I push a crystal?
Hi Ed, I seriously doubt you will be able to pull the 10 MHz crystal tht far off. International Crystal Manufacturering (ICM) http://www.icmfg.com/ still makes crystals for a reasonable amount (about $25) cut to order. That may be far easier than all the time you would spend bending and pushing things around trying stretch components. BillWB6BNQ Ed Breya wrote: I've got to make a very clean 10.0594... MHz VCXO for a redo of one of my old circuits. I previously used a 10 MHz ceramic resonator, which was easy enough to push around in frequency. Of course, I have a couple dozen of those somewhere, but can't find them now that I need them again. I figured I'd just pull the ones out of the old circuit, but since I did find a whole bunch of 10 MHz quartz crystals, I'd like to revisit whether I can push one of those that far with decent results. As I recall, the results of my previous experiments in doing this were less than satisfactory, which is why I went with the ceramics. This would be a change of 60 kHz out of 10 MHz, or 0.6 percent - a helluva lot for a crystal. The frequency will be exactly phase locked to a reference. It doesn't need to have extremely high in-circuit Q or long-term stability - just tunable to that magic number - the PLL will do the rest. A conventional varicap circuit will provide the VCO-ness, while the tuning range just needs to be enough to accommodate drift and the initial setting. The power gain element will be a 74HC04 or 74HC86 section. The PLL reference will be 59.4... kHz - way above the necessary loop BW. Has anyone successfully pushed a quartz crystal that far off, with reliable (still sort of a sharp resonance) operation and no spurious modes? Any ideas? If this isn't practical, I'll just go back to the ceramic resonator (which worked just fine), but I'd like to settle it once and for all. Ed ___ 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] How far can I push a crystal?
Hi Mouser shows 16 items tighter than +/- 20 ppm accuracy. Six of them are in stock and less than $1 in single piece quantities. The cheapest is 39 cents. Bob On Jan 17, 2013, at 7:38 PM, WB6BNQ wb6...@cox.net wrote: Hi Ed, I seriously doubt you will be able to pull the 10 MHz crystal tht far off. International Crystal Manufacturering (ICM) http://www.icmfg.com/ still makes crystals for a reasonable amount (about $25) cut to order. That may be far easier than all the time you would spend bending and pushing things around trying stretch components. BillWB6BNQ Ed Breya wrote: I've got to make a very clean 10.0594... MHz VCXO for a redo of one of my old circuits. I previously used a 10 MHz ceramic resonator, which was easy enough to push around in frequency. Of course, I have a couple dozen of those somewhere, but can't find them now that I need them again. I figured I'd just pull the ones out of the old circuit, but since I did find a whole bunch of 10 MHz quartz crystals, I'd like to revisit whether I can push one of those that far with decent results. As I recall, the results of my previous experiments in doing this were less than satisfactory, which is why I went with the ceramics. This would be a change of 60 kHz out of 10 MHz, or 0.6 percent - a helluva lot for a crystal. The frequency will be exactly phase locked to a reference. It doesn't need to have extremely high in-circuit Q or long-term stability - just tunable to that magic number - the PLL will do the rest. A conventional varicap circuit will provide the VCO-ness, while the tuning range just needs to be enough to accommodate drift and the initial setting. The power gain element will be a 74HC04 or 74HC86 section. The PLL reference will be 59.4... kHz - way above the necessary loop BW. Has anyone successfully pushed a quartz crystal that far off, with reliable (still sort of a sharp resonance) operation and no spurious modes? Any ideas? If this isn't practical, I'll just go back to the ceramic resonator (which worked just fine), but I'd like to settle it once and for all. Ed ___ 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] How far can I push a crystal?
Bob, are you saying they have 10.059 MHz crystals? I've never seen one anywhere, or anything even close. Ed Hi Mouser shows 16 items tighter than +/- 20 ppm accuracy. Six of them are in stock and less than $1 in single piece quantities. The cheapest is 39 cents. 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] How far can I push a crystal?
HI Sorry, I mis-read the original post. Bob On Jan 17, 2013, at 8:09 PM, Ed Breya e...@telight.com wrote: Bob, are you saying they have 10.059 MHz crystals? I've never seen one anywhere, or anything even close. Ed Hi Mouser shows 16 items tighter than +/- 20 ppm accuracy. Six of them are in stock and less than $1 in single piece quantities. The cheapest is 39 cents. 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] How far can I push a crystal?
Maybe I should clarify what I meant by pushing the crystal frequency. I meant only using various topologies and electronic components in the associated circuitry, that would detune it from its natural resonance far enough to reach the new frequency, and still have it be sort of a narrow-bandwidth crystal oscillator - not doing any mechanical changes to the crystal element itself. Since the ceramic resonators seem to work well, and can be pushed (or pulled?) fairly far away by proper selection of the associated component values, I was wondering how far quartz crystals can reasonably go. I encounter this situation often - needing an oddball frequency, but preferring to use common or standard parts. The nominal choices in ceramic are quite limited, while in crystals, there are many more - but few ever seem to land at or near enough to a frequency I need. The only thing I have thought of so far is to maybe add some series R to drop the crystal Q, so broadening the resonance, and just dragging it up by extra series C, but at some point there's no point to even having the crystal there at all. I'm just trying to figure out what's possible and reasonable. I know that I can get any custom frequency by spending enough money, but that takes the challenge and fun out it sometimes. Ed ___ 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] How far can I push a crystal?
Having just adjusted a crystal oscillator at 10.715 MHz, I would hazard a guess that the most one can easily pull a crystal of nominal frequency around 10 MHz would be of the order of +/-1 kHz. Certainly not 60 kHz. dr ___ 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] How far can I push a crystal?
Ed Breya wrote: Maybe I should clarify what I meant by pushing the crystal frequency. I meant only using various topologies and electronic components in the associated circuitry, that would detune it from its natural resonance far enough to reach the new frequency, and still have it be sort of a narrow-bandwidth crystal oscillator - not doing any mechanical changes to the crystal element itself. Since the ceramic resonators seem to work well, and can be pushed (or pulled?) fairly far away by proper selection of the associated component values, I was wondering how far quartz crystals can reasonably go. I Since you asked: You can get something like a range of 0.1% by resonating out the holder capacitance with a shunt inductor. You then put this assembly in series with an inductor and varactor. If you want to get into the lunatic fringe, you use a high Q inductor wound on Fair-Rite 61 or 67. Now you can seriously pull the crystal below its resonant frequency. How far you can go depends on the Q of the inductor. I am not sure if you can also pull it above, but even if you could, there are spurious resonances up there that could get you. The lunatic fringe might get you .2 or .3%, still not .6%. You'll definitely take a hit in temperature stability and phase noise with high pulling. If you don't have experience with VCXO's, you will find the circuit design quite challenging. It wasn't clear if you needed a 10.05944 MHz VCXO, or just a source at that frequency. There a lots of one chip synthesizers that could generate that frequency as I'm sure you know. 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] How far can I push a crystal?
Bernd Neubig wrote: A parallel inductor for compensation of the static capacitance C0 does not help much at 10 MHz, because such a coil, which resonates out a 6 pF capacitance has an internal winding capacitance, which is larger than 6 pF. So you would need a coil which has a self-resonance of slightly above 10 MHz. Actually, a parallel inductor helps a lot and is essential for getting a large pulling range. Modern surface mount coils have a self capacitance of a fraction of a pF, not 6 pF, and in any event, you can always find an inductor that is resonant when combined with the crystal. The nominal value of this inductor may be considerably less than the calculated value, but there is always some value of inductor that works. This was true even in the through hole era. 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] How far can I push a crystal?
Thanks all, for the feedback on this issue. In summary, I got these points out of the discussion on crystals: 1. The correct terminology is pulling the frequency. 2. Getting beyond about a few hundred ppm from the nominal frequency ranges from very difficult to pointless. 3. It's easier to pull down than up. It looks like it would not be worth fooling around with crystals, so I'll just use the ceramic resonators. By the way, I just tonight managed to reach the correct geological layer of stuff out in the garage, and found the missing 10 MHz resonators, and a whole tray of other parts that were in reserve for completing this project from a couple of years ago. For the curious: The 10.059... MHz is made by a PLL using the 59.... kHz reference, which is 10.7 MHz divided by 180. The 10.7 MHz is a from another VCXO (which can use a standard crystal, ceramic resonator, or ceramic IF filter - easy) that's phase locked to a 10 or 1 MHz reference, using two fixed dividers. The 10.059... MHz is used as the reference for a phase locked microwave brick oscillator, using n=120, to make 1207.1333... MHz, which is exactly one-third of 3621.4 MHz, the low-band upconversion IF of the HP8566B spectrum analyzer. The 1207.1333... MHz is harmonically mixed (m=3) with the first LO of the SA to produce the tracking signal centered in the passband of the SA. All of this is built into the modified carcass of an HP8443A tracking generator, originally built for older SA models. Using the new stuff, plus parts of the 8443A, the net result is a 50 kHz to 250 MHz tracking generator, with power up to +10 dBm, leveled within about 1 dB, and with 130 dB step attenuator range - very nice for low RF and baseband work. The 10.059... MHz is only one of many frequencies that could be multiplied by various n-values to give the same result, but it was chosen because it was very close to a standard frequency available in ceramic resonators, high enough that n didn't need to be too large, and it could be synthesized with a very simple PLL system. I had all of this built and running, but I had made the fatal engineering mistake of putting way too much stuff in too small a space. Space was tight, so I squeezed the entire LF control system and synthesizers into one small can, and necessarily optimized for minimum IC package count. Then I found that there was too much crosstalk between virtually all the signals in the box, so there was too much phase noise to work at 300 Hz and less IFBW. The problems were irreversible - sharing IC packages for multiple signal processing was an especially bad move. After many hours of rearranging signal paths, adding shielding and grounds, and changing topologies, I concluded that I had to rebuild it the right way. So here I am. The two main frequencies will be generated in separate boxes, and no ICs will contain multiple signals that aren't being processed together. This time I'll get it right, and finally wrap it up. Ed ___ 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.
