Re: [time-nuts] Wavecrest DTS-2077 Teardown
Hi Not all semiconductor processes are created equal. In order to get things going faster you change things around. Past a point, those same changes negatively impact the leakage and 1/f noise corner. When all the changes happen, the jitter goes up. That turns it very much into a test it and see sort of thing. You can not just pick the device off a data sheet. Bob On Aug 21, 2013, at 4:44 PM, Ed Palmer ed_pal...@sasktel.net w Since you're looking for rise times in the low or sub nanosecond range, why wouldn't you include any logic gates where such rise times are inherent? I was thinking of maybe a chain of faster and faster logic gates. For example, Potato Semiconductor - no, I'm not making that up - PO74G04A has a risetime of 1 ns and, if you can keep the load capacitance low enough, a maximum input frequency of 1 GHz. Always trying to learn Ed On 8/20/2013 11:28 PM, Bruce Griffiths wrote: The same analysis applies however one would probably use something like cascaded longtailed pairs with well defined gain (series emitter feedback) and the low pass filter cap connected between the collectors rather than opamps. Bruce Ed Palmer wrote: Does anyone know if this situation would benefit from doing something similar to a 'Collins Hard Limiter' i.e. instead of squaring the signal in one stage, use maybe two or three cascaded stages with increasing bandwidths? Normally, Collins limiters are used with beat frequencies of less than 1 KHz, but maybe there's value in doing at typical time-nuts frequencies. Any thoughts? Ed On 8/20/2013 10:02 PM, Said Jackson wrote: Hi Ed, For anything up to about 150MHz try the NC74SZ04 types from National if you can find them NOS. they stopped making these years ago.. Fairchild is ok too but not as fast from what I have seen. Forgot I wrote about it in 2009. Oh boy -age kicking in. Bye, Said Sent From iPhone On Aug 20, 2013, at 20:17, Ed Palmer ed_pal...@sasktel.net wrote: Hi Said, Yes, I saw your message from 2009 where you warned about the sine waves. That's why I was watching for it. Thanks for the warning. I also realized that a DC Block and a 10 db attenuator makes a very nice TTL or CMOS to Wavecrest converter for anything except 1 PPS which would need about 15 db. I tried an old circuit that uses an MC10116 ecl line receiver - it's actually a dead Racal Dana 1992 counter where I'm using the processing on the external reference input to square up the signal. It gives me a slew rate equivalent to about a 50 MHz sine wave. It helped a lot, but not enough. I'll try a 74AC04 and a BRS2G Differential Line Receiver (risetime 3ns, 400Mbps throughput). Both are in my junkbox. Ed On 8/20/2013 8:12 PM, Said Jackson wrote: Guys, The dts needs to be driven by square waves, driving them with sine waves gives jitter values that are displayed significantly too high due to trigger noise. Holzworth makes a small sine wave to square wave converter that can drive 50 ohms. Use a DC block and an attenuator on the cmos output to avoid damaging the dts inputs. You can make your own converter using a single fast cmos gate, resistor, and blocking cap. By using hand-selected gates I was able to achieve less jitter with that circuit than what the Holzworth box was able to achieve. Doing that conversion can bring down the measured rms jitter on a very good 10MHz sine wave source from 10ps+ to less than 2ps - basically at or below the noise floor of the dts.. Once you run at the units' noise floor, you know your source is quite good.. Bye, Said Sent From iPhone On Aug 20, 2013, at 18:51, Ed Palmer ed_pal...@sasktel.net wrote: Adrian, I used Timelab to assess the reaction of the DTS-2077 to different sine wave inputs. The differences in the noise floor are surprising. The attached picture was made by taking the output of an HP 8647A Synthesized Generator through a splitter, and then through different lengths of cables to the inputs of the DTS-2077. The combination of splitter and cable loss meant I couldn't get +7 dbm @ 1 GHz. If I could have, the 1 GHz line might have been lower than it was. 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] Wavecrest DTS-2077 Teardown
Sounds like I need to do some experiments. Thanks for the advice and idea, Bruce. :) Ed On 8/22/2013 12:15 AM, Bruce Griffiths wrote: That will work to some extent however you need to tailor the stage gain and bandwidth distribution to suit for optimum performance. Its somewhat difficult to control the gain and bandwidth of an off the shelf CMOS inverter and you also need to know its noise parameters. Maybe adding resistors in series with the power supply leads of the CMOS inveters and adding some output capacitance will suffice to adjust the gain and bandwidth. Bruce Ed Palmer wrote: Since you're looking for rise times in the low or sub nanosecond range, why wouldn't you include any logic gates where such rise times are inherent? I was thinking of maybe a chain of faster and faster logic gates. For example, Potato Semiconductor - no, I'm not making that up - PO74G04A has a risetime of 1 ns and, if you can keep the load capacitance low enough, a maximum input frequency of 1 GHz. Always trying to learn Ed On 8/20/2013 11:28 PM, Bruce Griffiths wrote: The same analysis applies however one would probably use something like cascaded longtailed pairs with well defined gain (series emitter feedback) and the low pass filter cap connected between the collectors rather than opamps. Bruce Ed Palmer wrote: Does anyone know if this situation would benefit from doing something similar to a 'Collins Hard Limiter' i.e. instead of squaring the signal in one stage, use maybe two or three cascaded stages with increasing bandwidths? Normally, Collins limiters are used with beat frequencies of less than 1 KHz, but maybe there's value in doing at typical time-nuts frequencies. Any thoughts? Ed On 8/20/2013 10:02 PM, Said Jackson wrote: Hi Ed, For anything up to about 150MHz try the NC74SZ04 types from National if you can find them NOS. they stopped making these years ago.. Fairchild is ok too but not as fast from what I have seen. Forgot I wrote about it in 2009. Oh boy -age kicking in. Bye, Said Sent From iPhone On Aug 20, 2013, at 20:17, Ed Palmer ed_pal...@sasktel.net wrote: Hi Said, Yes, I saw your message from 2009 where you warned about the sine waves. That's why I was watching for it. Thanks for the warning. I also realized that a DC Block and a 10 db attenuator makes a very nice TTL or CMOS to Wavecrest converter for anything except 1 PPS which would need about 15 db. I tried an old circuit that uses an MC10116 ecl line receiver - it's actually a dead Racal Dana 1992 counter where I'm using the processing on the external reference input to square up the signal. It gives me a slew rate equivalent to about a 50 MHz sine wave. It helped a lot, but not enough. I'll try a 74AC04 and a BRS2G Differential Line Receiver (risetime 3ns, 400Mbps throughput). Both are in my junkbox. Ed On 8/20/2013 8:12 PM, Said Jackson wrote: Guys, The dts needs to be driven by square waves, driving them with sine waves gives jitter values that are displayed significantly too high due to trigger noise. Holzworth makes a small sine wave to square wave converter that can drive 50 ohms. Use a DC block and an attenuator on the cmos output to avoid damaging the dts inputs. You can make your own converter using a single fast cmos gate, resistor, and blocking cap. By using hand-selected gates I was able to achieve less jitter with that circuit than what the Holzworth box was able to achieve. Doing that conversion can bring down the measured rms jitter on a very good 10MHz sine wave source from 10ps+ to less than 2ps - basically at or below the noise floor of the dts.. Once you run at the units' noise floor, you know your source is quite good.. Bye, Said Sent From iPhone On Aug 20, 2013, at 18:51, Ed Palmer ed_pal...@sasktel.net wrote: Adrian, I used Timelab to assess the reaction of the DTS-2077 to different sine wave inputs. The differences in the noise floor are surprising. The attached picture was made by taking the output of an HP 8647A Synthesized Generator through a splitter, and then through different lengths of cables to the inputs of the DTS-2077. The combination of splitter and cable loss meant I couldn't get +7 dbm @ 1 GHz. If I could have, the 1 GHz line might have been lower than it was. 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] Wavecrest DTS-2077 Teardown
Since you're looking for rise times in the low or sub nanosecond range, why wouldn't you include any logic gates where such rise times are inherent? I was thinking of maybe a chain of faster and faster logic gates. For example, Potato Semiconductor - no, I'm not making that up - PO74G04A has a risetime of 1 ns and, if you can keep the load capacitance low enough, a maximum input frequency of 1 GHz. Always trying to learn Ed On 8/20/2013 11:28 PM, Bruce Griffiths wrote: The same analysis applies however one would probably use something like cascaded longtailed pairs with well defined gain (series emitter feedback) and the low pass filter cap connected between the collectors rather than opamps. Bruce Ed Palmer wrote: Does anyone know if this situation would benefit from doing something similar to a 'Collins Hard Limiter' i.e. instead of squaring the signal in one stage, use maybe two or three cascaded stages with increasing bandwidths? Normally, Collins limiters are used with beat frequencies of less than 1 KHz, but maybe there's value in doing at typical time-nuts frequencies. Any thoughts? Ed On 8/20/2013 10:02 PM, Said Jackson wrote: Hi Ed, For anything up to about 150MHz try the NC74SZ04 types from National if you can find them NOS. they stopped making these years ago.. Fairchild is ok too but not as fast from what I have seen. Forgot I wrote about it in 2009. Oh boy -age kicking in. Bye, Said Sent From iPhone On Aug 20, 2013, at 20:17, Ed Palmer ed_pal...@sasktel.net wrote: Hi Said, Yes, I saw your message from 2009 where you warned about the sine waves. That's why I was watching for it. Thanks for the warning. I also realized that a DC Block and a 10 db attenuator makes a very nice TTL or CMOS to Wavecrest converter for anything except 1 PPS which would need about 15 db. I tried an old circuit that uses an MC10116 ecl line receiver - it's actually a dead Racal Dana 1992 counter where I'm using the processing on the external reference input to square up the signal. It gives me a slew rate equivalent to about a 50 MHz sine wave. It helped a lot, but not enough. I'll try a 74AC04 and a BRS2G Differential Line Receiver (risetime 3ns, 400Mbps throughput). Both are in my junkbox. Ed On 8/20/2013 8:12 PM, Said Jackson wrote: Guys, The dts needs to be driven by square waves, driving them with sine waves gives jitter values that are displayed significantly too high due to trigger noise. Holzworth makes a small sine wave to square wave converter that can drive 50 ohms. Use a DC block and an attenuator on the cmos output to avoid damaging the dts inputs. You can make your own converter using a single fast cmos gate, resistor, and blocking cap. By using hand-selected gates I was able to achieve less jitter with that circuit than what the Holzworth box was able to achieve. Doing that conversion can bring down the measured rms jitter on a very good 10MHz sine wave source from 10ps+ to less than 2ps - basically at or below the noise floor of the dts.. Once you run at the units' noise floor, you know your source is quite good.. Bye, Said Sent From iPhone On Aug 20, 2013, at 18:51, Ed Palmer ed_pal...@sasktel.net wrote: Adrian, I used Timelab to assess the reaction of the DTS-2077 to different sine wave inputs. The differences in the noise floor are surprising. The attached picture was made by taking the output of an HP 8647A Synthesized Generator through a splitter, and then through different lengths of cables to the inputs of the DTS-2077. The combination of splitter and cable loss meant I couldn't get +7 dbm @ 1 GHz. If I could have, the 1 GHz line might have been lower than it was. 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] Wavecrest DTS-2077 Teardown
On 08/21/2013 03:51 AM, Ed Palmer wrote: Adrian, I used Timelab to assess the reaction of the DTS-2077 to different sine wave inputs. The differences in the noise floor are surprising. The attached picture was made by taking the output of an HP 8647A Synthesized Generator through a splitter, and then through different lengths of cables to the inputs of the DTS-2077. The combination of splitter and cable loss meant I couldn't get +7 dbm @ 1 GHz. If I could have, the 1 GHz line might have been lower than it was. This is not very surprising. As you increase frequency, the slew-rate changes, and as slewrate increases, it convert noise to jitter to a lesser degree. Formula for slew-rate: S = A*2*pi*f where A is the amplitude and f is the frequency Formula for jitter T = e_n / S where e_n is the noise RMS amplitude, S the slew-rate and T the timing jitter RMS. As you get closer to the instruments internal jitter, which forms a floor, the increased slew-rate does not improve as quickly as you would think. 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] Wavecrest DTS-2077 Teardown
On 08/21/2013 06:46 AM, Ed Palmer wrote: Does anyone know if this situation would benefit from doing something similar to a 'Collins Hard Limiter' i.e. instead of squaring the signal in one stage, use maybe two or three cascaded stages with increasing bandwidths? Normally, Collins limiters are used with beat frequencies of less than 1 KHz, but maybe there's value in doing at typical time-nuts frequencies. Any thoughts? The input stage of the TADD-2 is a good example, with direct inspiration from Wenzel it amplifies the signal up. I then use the result to drive a spare output and there I get much less jitter than the sine 5 MHz alone. So, the application is low-jitter signal. 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] Wavecrest DTS-2077 Teardown
On 8/21/2013 5:52 PM, Magnus Danielson wrote: On 08/21/2013 03:51 AM, Ed Palmer wrote: Adrian, I used Timelab to assess the reaction of the DTS-2077 to different sine wave inputs. The differences in the noise floor are surprising. The attached picture was made by taking the output of an HP 8647A Synthesized Generator through a splitter, and then through different lengths of cables to the inputs of the DTS-2077. The combination of splitter and cable loss meant I couldn't get +7 dbm @ 1 GHz. If I could have, the 1 GHz line might have been lower than it was. This is not very surprising. As you increase frequency, the slew-rate changes, and as slewrate increases, it convert noise to jitter to a lesser degree. Formula for slew-rate: S = A*2*pi*f where A is the amplitude and f is the frequency Formula for jitter T = e_n / S where e_n is the noise RMS amplitude, S the slew-rate and T the timing jitter RMS. As you get closer to the instruments internal jitter, which forms a floor, the increased slew-rate does not improve as quickly as you would think. Cheers, Magnus Yes, I realize all that. Since I couldn't vary the slew rate of a pulse, I used sine waves to 'stand in' for varying slew rates to find the value that didn't degrade the results. 5 or 10 MHz is a high enough frequency that most equipment won't have a problem with it. But the DTS has such a high level of performance that you need to pay special attention to the quality of the input signal. It would have been nice if Wavecrest had at least mentioned it in the manual as something to be considered. Not doing so can result in misuse by the operator that makes their equipment look bad. I had to think about the poor results I was seeing. At first I wondered if my unit was defective. I haven't read through all their app notes so there could be something buried in there. I know that other vendors do discuss this topic in either manuals or app notes related to their counters. HP App Note 200 is a good example of this. But it's worth noting that in a table of Trigger Error vs. Slew Rate, the lowest trigger error listed is 10ns - not even remotely close to the performance level of the DTS even though the copyright date is similar to the DTS's production date. We tend to fall into a rut when it's never been a problem before. Equipment vendors need to warn us when their equipment makes our previous assumptions invalid. 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] Wavecrest DTS-2077 Teardown
FYI, I did a teardown on my Wavecrest DTS-2077. It's posted here: http://www.eevblog.com/forum/testgear/wavecrest-dts-2077-teardown 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] Wavecrest DTS-2077 Teardown
Hi Ed, Nice story with nice pictures. Can you make full resolution pictures available please. The 2070 and 2075 look the same, at least as far I could see. But your picture show more of the inners than I saw when I opened mine. Henk Op 20 aug. 2013, om 20:51 heeft Mike Feher mfe...@eozinc.com het volgende geschreven: Good going Ed. I have two of them that I never even played with yet, other than to turn them on. While I saved your write-up, I hope I will never need to refer to it. Regards - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Ed Palmer Sent: Tuesday, August 20, 2013 2:17 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] Wavecrest DTS-2077 Teardown FYI, I did a teardown on my Wavecrest DTS-2077. It's posted here: http://www.eevblog.com/forum/testgear/wavecrest-dts-2077-teardown 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] Wavecrest DTS-2077 Teardown
I wondered who would be the first to ask for the hires photos. :) I've posted them here: http://s701.photobucket.com/user/edpalmer42/library/Wavecrest DTS-2077 Ed On 8/20/2013 1:01 PM, Henk ten Pierick wrote: Hi Ed, Nice story with nice pictures. Can you make full resolution pictures available please. The 2070 and 2075 look the same, at least as far I could see. But your picture show more of the inners than I saw when I opened mine. Henk Op 20 aug. 2013, om 20:51 heeft Mike Feher mfe...@eozinc.com het volgende geschreven: Good going Ed. I have two of them that I never even played with yet, other than to turn them on. While I saved your write-up, I hope I will never need to refer to it. Regards - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-902-3831 cell -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Ed Palmer Sent: Tuesday, August 20, 2013 2:17 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] Wavecrest DTS-2077 Teardown FYI, I did a teardown on my Wavecrest DTS-2077. It's posted here: http://www.eevblog.com/forum/testgear/wavecrest-dts-2077-teardown 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] Wavecrest DTS-2077 Teardown
Ed, thanks for posting! I'm still looking for a MUX board for my faulty 2077. Is there anyone using a DTS-207x with TimeLab? Adrian Ed Palmer schrieb: FYI, I did a teardown on my Wavecrest DTS-2077. It's posted here: http://www.eevblog.com/forum/testgear/wavecrest-dts-2077-teardown 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] Wavecrest DTS-2077 Teardown
Guys, The dts needs to be driven by square waves, driving them with sine waves gives jitter values that are displayed significantly too high due to trigger noise. Holzworth makes a small sine wave to square wave converter that can drive 50 ohms. Use a DC block and an attenuator on the cmos output to avoid damaging the dts inputs. You can make your own converter using a single fast cmos gate, resistor, and blocking cap. By using hand-selected gates I was able to achieve less jitter with that circuit than what the Holzworth box was able to achieve. Doing that conversion can bring down the measured rms jitter on a very good 10MHz sine wave source from 10ps+ to less than 2ps - basically at or below the noise floor of the dts.. Once you run at the units' noise floor, you know your source is quite good.. Bye, Said Sent From iPhone On Aug 20, 2013, at 18:51, Ed Palmer ed_pal...@sasktel.net wrote: Adrian, I used Timelab to assess the reaction of the DTS-2077 to different sine wave inputs. The differences in the noise floor are surprising. The attached picture was made by taking the output of an HP 8647A Synthesized Generator through a splitter, and then through different lengths of cables to the inputs of the DTS-2077. The combination of splitter and cable loss meant I couldn't get +7 dbm @ 1 GHz. If I could have, the 1 GHz line might have been lower than it was. Ed On 8/20/2013 4:42 PM, Adrian wrote: Ed, thanks for posting! I'm still looking for a MUX board for my faulty 2077. Is there anyone using a DTS-207x with TimeLab? Adrian Ed Palmer schrieb: FYI, I did a teardown on my Wavecrest DTS-2077. It's posted here: http://www.eevblog.com/forum/testgear/wavecrest-dts-2077-teardown Ed DTS-2077 Noise Floor.png ___ 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] Wavecrest DTS-2077 Teardown
Hi Said, Yes, I saw your message from 2009 where you warned about the sine waves. That's why I was watching for it. Thanks for the warning. I also realized that a DC Block and a 10 db attenuator makes a very nice TTL or CMOS to Wavecrest converter for anything except 1 PPS which would need about 15 db. I tried an old circuit that uses an MC10116 ecl line receiver - it's actually a dead Racal Dana 1992 counter where I'm using the processing on the external reference input to square up the signal. It gives me a slew rate equivalent to about a 50 MHz sine wave. It helped a lot, but not enough. I'll try a 74AC04 and a BRS2G Differential Line Receiver (risetime 3ns, 400Mbps throughput). Both are in my junkbox. Ed On 8/20/2013 8:12 PM, Said Jackson wrote: Guys, The dts needs to be driven by square waves, driving them with sine waves gives jitter values that are displayed significantly too high due to trigger noise. Holzworth makes a small sine wave to square wave converter that can drive 50 ohms. Use a DC block and an attenuator on the cmos output to avoid damaging the dts inputs. You can make your own converter using a single fast cmos gate, resistor, and blocking cap. By using hand-selected gates I was able to achieve less jitter with that circuit than what the Holzworth box was able to achieve. Doing that conversion can bring down the measured rms jitter on a very good 10MHz sine wave source from 10ps+ to less than 2ps - basically at or below the noise floor of the dts.. Once you run at the units' noise floor, you know your source is quite good.. Bye, Said Sent From iPhone On Aug 20, 2013, at 18:51, Ed Palmer ed_pal...@sasktel.net wrote: Adrian, I used Timelab to assess the reaction of the DTS-2077 to different sine wave inputs. The differences in the noise floor are surprising. The attached picture was made by taking the output of an HP 8647A Synthesized Generator through a splitter, and then through different lengths of cables to the inputs of the DTS-2077. The combination of splitter and cable loss meant I couldn't get +7 dbm @ 1 GHz. If I could have, the 1 GHz line might have been lower than it was. 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] Wavecrest DTS-2077 Teardown
Hi Ed, For anything up to about 150MHz try the NC74SZ04 types from National if you can find them NOS. they stopped making these years ago.. Fairchild is ok too but not as fast from what I have seen. Forgot I wrote about it in 2009. Oh boy -age kicking in. Bye, Said Sent From iPhone On Aug 20, 2013, at 20:17, Ed Palmer ed_pal...@sasktel.net wrote: Hi Said, Yes, I saw your message from 2009 where you warned about the sine waves. That's why I was watching for it. Thanks for the warning. I also realized that a DC Block and a 10 db attenuator makes a very nice TTL or CMOS to Wavecrest converter for anything except 1 PPS which would need about 15 db. I tried an old circuit that uses an MC10116 ecl line receiver - it's actually a dead Racal Dana 1992 counter where I'm using the processing on the external reference input to square up the signal. It gives me a slew rate equivalent to about a 50 MHz sine wave. It helped a lot, but not enough. I'll try a 74AC04 and a BRS2G Differential Line Receiver (risetime 3ns, 400Mbps throughput). Both are in my junkbox. Ed On 8/20/2013 8:12 PM, Said Jackson wrote: Guys, The dts needs to be driven by square waves, driving them with sine waves gives jitter values that are displayed significantly too high due to trigger noise. Holzworth makes a small sine wave to square wave converter that can drive 50 ohms. Use a DC block and an attenuator on the cmos output to avoid damaging the dts inputs. You can make your own converter using a single fast cmos gate, resistor, and blocking cap. By using hand-selected gates I was able to achieve less jitter with that circuit than what the Holzworth box was able to achieve. Doing that conversion can bring down the measured rms jitter on a very good 10MHz sine wave source from 10ps+ to less than 2ps - basically at or below the noise floor of the dts.. Once you run at the units' noise floor, you know your source is quite good.. Bye, Said Sent From iPhone On Aug 20, 2013, at 18:51, Ed Palmer ed_pal...@sasktel.net wrote: Adrian, I used Timelab to assess the reaction of the DTS-2077 to different sine wave inputs. The differences in the noise floor are surprising. The attached picture was made by taking the output of an HP 8647A Synthesized Generator through a splitter, and then through different lengths of cables to the inputs of the DTS-2077. The combination of splitter and cable loss meant I couldn't get +7 dbm @ 1 GHz. If I could have, the 1 GHz line might have been lower than it was. 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] Wavecrest DTS-2077 Teardown
Does anyone know if this situation would benefit from doing something similar to a 'Collins Hard Limiter' i.e. instead of squaring the signal in one stage, use maybe two or three cascaded stages with increasing bandwidths? Normally, Collins limiters are used with beat frequencies of less than 1 KHz, but maybe there's value in doing at typical time-nuts frequencies. Any thoughts? Ed On 8/20/2013 10:02 PM, Said Jackson wrote: Hi Ed, For anything up to about 150MHz try the NC74SZ04 types from National if you can find them NOS. they stopped making these years ago.. Fairchild is ok too but not as fast from what I have seen. Forgot I wrote about it in 2009. Oh boy -age kicking in. Bye, Said Sent From iPhone On Aug 20, 2013, at 20:17, Ed Palmer ed_pal...@sasktel.net wrote: Hi Said, Yes, I saw your message from 2009 where you warned about the sine waves. That's why I was watching for it. Thanks for the warning. I also realized that a DC Block and a 10 db attenuator makes a very nice TTL or CMOS to Wavecrest converter for anything except 1 PPS which would need about 15 db. I tried an old circuit that uses an MC10116 ecl line receiver - it's actually a dead Racal Dana 1992 counter where I'm using the processing on the external reference input to square up the signal. It gives me a slew rate equivalent to about a 50 MHz sine wave. It helped a lot, but not enough. I'll try a 74AC04 and a BRS2G Differential Line Receiver (risetime 3ns, 400Mbps throughput). Both are in my junkbox. Ed On 8/20/2013 8:12 PM, Said Jackson wrote: Guys, The dts needs to be driven by square waves, driving them with sine waves gives jitter values that are displayed significantly too high due to trigger noise. Holzworth makes a small sine wave to square wave converter that can drive 50 ohms. Use a DC block and an attenuator on the cmos output to avoid damaging the dts inputs. You can make your own converter using a single fast cmos gate, resistor, and blocking cap. By using hand-selected gates I was able to achieve less jitter with that circuit than what the Holzworth box was able to achieve. Doing that conversion can bring down the measured rms jitter on a very good 10MHz sine wave source from 10ps+ to less than 2ps - basically at or below the noise floor of the dts.. Once you run at the units' noise floor, you know your source is quite good.. Bye, Said Sent From iPhone On Aug 20, 2013, at 18:51, Ed Palmer ed_pal...@sasktel.net wrote: Adrian, I used Timelab to assess the reaction of the DTS-2077 to different sine wave inputs. The differences in the noise floor are surprising. The attached picture was made by taking the output of an HP 8647A Synthesized Generator through a splitter, and then through different lengths of cables to the inputs of the DTS-2077. The combination of splitter and cable loss meant I couldn't get +7 dbm @ 1 GHz. If I could have, the 1 GHz line might have been lower than it was. 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] Wavecrest DTS-2077 Teardown
The same analysis applies however one would probably use something like cascaded longtailed pairs with well defined gain (series emitter feedback) and the low pass filter cap connected between the collectors rather than opamps. Bruce Ed Palmer wrote: Does anyone know if this situation would benefit from doing something similar to a 'Collins Hard Limiter' i.e. instead of squaring the signal in one stage, use maybe two or three cascaded stages with increasing bandwidths? Normally, Collins limiters are used with beat frequencies of less than 1 KHz, but maybe there's value in doing at typical time-nuts frequencies. Any thoughts? Ed On 8/20/2013 10:02 PM, Said Jackson wrote: Hi Ed, For anything up to about 150MHz try the NC74SZ04 types from National if you can find them NOS. they stopped making these years ago.. Fairchild is ok too but not as fast from what I have seen. Forgot I wrote about it in 2009. Oh boy -age kicking in. Bye, Said Sent From iPhone On Aug 20, 2013, at 20:17, Ed Palmer ed_pal...@sasktel.net wrote: Hi Said, Yes, I saw your message from 2009 where you warned about the sine waves. That's why I was watching for it. Thanks for the warning. I also realized that a DC Block and a 10 db attenuator makes a very nice TTL or CMOS to Wavecrest converter for anything except 1 PPS which would need about 15 db. I tried an old circuit that uses an MC10116 ecl line receiver - it's actually a dead Racal Dana 1992 counter where I'm using the processing on the external reference input to square up the signal. It gives me a slew rate equivalent to about a 50 MHz sine wave. It helped a lot, but not enough. I'll try a 74AC04 and a BRS2G Differential Line Receiver (risetime 3ns, 400Mbps throughput). Both are in my junkbox. Ed On 8/20/2013 8:12 PM, Said Jackson wrote: Guys, The dts needs to be driven by square waves, driving them with sine waves gives jitter values that are displayed significantly too high due to trigger noise. Holzworth makes a small sine wave to square wave converter that can drive 50 ohms. Use a DC block and an attenuator on the cmos output to avoid damaging the dts inputs. You can make your own converter using a single fast cmos gate, resistor, and blocking cap. By using hand-selected gates I was able to achieve less jitter with that circuit than what the Holzworth box was able to achieve. Doing that conversion can bring down the measured rms jitter on a very good 10MHz sine wave source from 10ps+ to less than 2ps - basically at or below the noise floor of the dts.. Once you run at the units' noise floor, you know your source is quite good.. Bye, Said Sent From iPhone On Aug 20, 2013, at 18:51, Ed Palmer ed_pal...@sasktel.net wrote: Adrian, I used Timelab to assess the reaction of the DTS-2077 to different sine wave inputs. The differences in the noise floor are surprising. The attached picture was made by taking the output of an HP 8647A Synthesized Generator through a splitter, and then through different lengths of cables to the inputs of the DTS-2077. The combination of splitter and cable loss meant I couldn't get +7 dbm @ 1 GHz. If I could have, the 1 GHz line might have been lower than it was. 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] Wavecrest DTS-2077 Teardown
A time interval counter or equivalent with less acoustical noise and internal jitter than the Wavecrest would be nice. Bruce Said Jackson wrote: Guys, The dts needs to be driven by square waves, driving them with sine waves gives jitter values that are displayed significantly too high due to trigger noise. Holzworth makes a small sine wave to square wave converter that can drive 50 ohms. Use a DC block and an attenuator on the cmos output to avoid damaging the dts inputs. You can make your own converter using a single fast cmos gate, resistor, and blocking cap. By using hand-selected gates I was able to achieve less jitter with that circuit than what the Holzworth box was able to achieve. Doing that conversion can bring down the measured rms jitter on a very good 10MHz sine wave source from 10ps+ to less than 2ps - basically at or below the noise floor of the dts.. Once you run at the units' noise floor, you know your source is quite good.. Bye, Said Sent From iPhone On Aug 20, 2013, at 18:51, Ed Palmered_pal...@sasktel.net wrote: Adrian, I used Timelab to assess the reaction of the DTS-2077 to different sine wave inputs. The differences in the noise floor are surprising. The attached picture was made by taking the output of an HP 8647A Synthesized Generator through a splitter, and then through different lengths of cables to the inputs of the DTS-2077. The combination of splitter and cable loss meant I couldn't get +7 dbm @ 1 GHz. If I could have, the 1 GHz line might have been lower than it was. Ed On 8/20/2013 4:42 PM, Adrian wrote: Ed, thanks for posting! I'm still looking for a MUX board for my faulty 2077. Is there anyone using a DTS-207x with TimeLab? Adrian Ed Palmer schrieb: FYI, I did a teardown on my Wavecrest DTS-2077. It's posted here: http://www.eevblog.com/forum/testgear/wavecrest-dts-2077-teardown Ed DTS-2077 Noise Floor.png ___ 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.
