Re: [time-nuts] 5061a now look at wrong freq A1 fault
Hi, C field will not get you on frequency with what you read right now, are you sure you are on the right peak? Bert Kehren ___ 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] My DIY frequency counter and a request for help
Hi Gerard,I'm not fully set up at the moment but if you've had no better offers I may be able to help.I'm located in Cambridge. My equipment includes a Thunderbolt GPSDO, two Efratom FRK-L Rubidiums, Oncore VP GPS, Phillips PM6654 time interval counter, Odetics satsync 325 GPSDO, Datum FTS-1000B OCXO and the usual 'scope, RF generator, spectrum analyser etc. Robert G8RPI. --- On Sat, 27/2/10, Gerard PG5G p...@b737.co.uk wrote: From: Gerard PG5G p...@b737.co.uk Subject: [time-nuts] My DIY frequency counter and a request for help To: time-nuts@febo.com Date: Saturday, 27 February, 2010, 9:36 Hello all, First post here, so I'll start with a quick introduction. I trained as an electronic engineer but don't work in that field any more, which has given me the appetite back to do some electronic engineering as a hobby. I have been a licensed ham for over 25 years (more than 60% of my life I realised the other day) and used to be rather active on HF as PA3DQW. At the moment I live in the UK where I am licensed as M0AIU. I recently designed and build a frequency counter and I need some help with verifying its performance. I believe it gives me 11 digits in 1 second. I say believe because I have not got the hardware to verify this. At the moment my assumption is based on calculations and limited testing with the equipment available to me. My counter is a continuous time stamping reciprocal counter. I implemented this as a USB powered device, with the hardware taking the time stamps and sending it over USB to a windows PC. Some software written in C++ takes care of analysing the data. The hardware takes 5000 time stamps per second using a high speed TDC. The hardware is a single PCB measuring about 50 by 80 mm. it requires an external 10MHz reference and apart from using this as the time base it also uses this for self-calibration of the TDC. The unit requires no further calibration. The PC software takes these time stamps and the associated counts and uses regression to calculate the slope. This slope represents the frequency of the input signal. I am sure people on here are familiar with the counters made by Pendulum, and I have to confess that their marketing material was helpful in putting this thing together. Since the hardware is true zero dead time, the final capabilities of this counter are determined by software. At the moment I can simultaneously display the input at multiple gate times (see the attached screen shot). For gate times over 1 second I have the option to use overlapping gates, so that the display gets updated every second. Because there is no dead time I can also calculate Allan Deviation. The two displays at the bottom of the page show both normal and overlapping Allan deviation at tau=10s. I am still working on the software to do this at multiple tau in real time and display it as a graph and a table. So, after this lengthy introduction here is my request for some assistance. Is there somebody on the list who can assist me in verifying the performance of this frequency counter? Ideally somebody with access to two highly stable and known frequency sources. I can send the hardware by mail, but if there happens to be somebody with this kind of gear not too far from where I am (50 north of London) I will travel. In exchange you get to keep the hardware and will be supplied with whatever software I come up with. Thanks in advance and regards, Gerard, PG5G -Inline Attachment Follows- ___ 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] 5061a now look at wrong freq A1 fault
Hi, let me start out with a disclaimer, I have sold several HP 5061A through a friend on ebay including the two recent HP 5062C's, the reason I do not do it direct is, he does it full time and he has the ability to get them packed professional. We have had no complaints all where tested and with the exception of the 5062C sold as fully funtional and till now there have been no complaints. Two more will be sold and are the best, kept till last. I would stay away from any C standard that has not been tested and even tested, it is a gamble because the question is how much life is left in the tube. I am sure there a members out there that have units with bad tubes. I am downsizing because I want to move to a smaller house and am now down to a modified 5062C with a FTS tube and a 5061B with a FTS tube. I have extra FTS tubes and did test them all and I know which are the best but I cannot tell what the expected life under normal continuos operation will be. I have tested beam current and will set up a standard test using 21.41 KHz and 2500 Volt electron multiplier. Maybe there is someone out there that has a correlation between beam current and expected life I know the end point and I know what you can see with a new tube but is there a curve that tells you what you can expect life wise? Right now I am only prepared to sell the two remaining working HP 5061A, maybe later the 5061B and after more testing some tubes. Any one interested please contact me directly. Bert Kehren,Miami ___ 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] 5061a now look at wrong freq A1 fault
Bert- I would be willing to take a chance on a used tube if the price was right. Please keep me in mind as I have been looking for a used Cs tube. -Brian, WA1ZMS Forest, VA On Feb 27, 2010, at 6:21 AM, ewkeh...@aol.com wrote: Hi, let me start out with a disclaimer, I have sold several HP 5061A through a friend on ebay including the two recent HP 5062C's, the reason I do not do it direct is, he does it full time and he has the ability to get them packed professional. We have had no complaints all where tested and with the exception of the 5062C sold as fully funtional and till now there have been no complaints. Two more will be sold and are the best, kept till last. I would stay away from any C standard that has not been tested and even tested, it is a gamble because the question is how much life is left in the tube. I am sure there a members out there that have units with bad tubes. I am downsizing because I want to move to a smaller house and am now down to a modified 5062C with a FTS tube and a 5061B with a FTS tube. I have extra FTS tubes and did test them all and I know which are the best but I cannot tell what the expected life under normal continuos operation will be. I have tested beam current and will set up a standard test using 21.41 KHz and 2500 Volt electron multiplier. Maybe there is someone out there that has a correlation between beam current and expected life I know the end point and I know what you can see with a new tube but is there a curve that tells you what you can expect life wise? Right now I am only prepared to sell the two remaining working HP 5061A, maybe later the 5061B and after more testing some tubes. Any one interested please contact me directly. Bert Kehren,Miami ___ 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. -Brian, WA1ZMS On Feb 27, 2010, at 6:21 AM, ewkeh...@aol.com wrote: Hi, let me start out with a disclaimer, I have sold several HP 5061A through a friend on ebay including the two recent HP 5062C's, the reason I do not do it direct is, he does it full time and he has the ability to get them packed professional. We have had no complaints all where tested and with the exception of the 5062C sold as fully funtional and till now there have been no complaints. Two more will be sold and are the best, kept till last. I would stay away from any C standard that has not been tested and even tested, it is a gamble because the question is how much life is left in the tube. I am sure there a members out there that have units with bad tubes. I am downsizing because I want to move to a smaller house and am now down to a modified 5062C with a FTS tube and a 5061B with a FTS tube. I have extra FTS tubes and did test them all and I know which are the best but I cannot tell what the expected life under normal continuos operation will be. I have tested beam current and will set up a standard test using 21.41 KHz and 2500 Volt electron multiplier. Maybe there is someone out there that has a correlation between beam current and expected life I know the end point and I know what you can see with a new tube but is there a curve that tells you what you can expect life wise? Right now I am only prepared to sell the two remaining working HP 5061A, maybe later the 5061B and after more testing some tubes. Any one interested please contact me directly. Bert Kehren,Miami ___ 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] My DIY frequency counter and a request for help
Gerard PG5G wrote: Hello all, First post here, so I'll start with a quick introduction. I trained as an electronic engineer but don't work in that field any more, which has given me the appetite back to do some electronic engineering as a hobby. I have been a licensed ham for over 25 years (more than 60% of my life I realised the other day) and used to be rather active on HF as PA3DQW. At the moment I live in the UK where I am licensed as M0AIU. I recently designed and build a frequency counter and I need some help with verifying its performance. I believe it gives me 11 digits in 1 second. I say believe because I have not got the hardware to verify this. At the moment my assumption is based on calculations and limited testing with the equipment available to me. My counter is a continuous time stamping reciprocal counter. I implemented this as a USB powered device, with the hardware taking the time stamps and sending it over USB to a windows PC. Some software written in C++ takes care of analysing the data. The hardware takes 5000 time stamps per second using a high speed TDC. The hardware is a single PCB measuring about 50 by 80 mm. it requires an external 10MHz reference and apart from using this as the time base it also uses this for self-calibration of the TDC. The unit requires no further calibration. The PC software takes these time stamps and the associated counts and uses regression to calculate the slope. This slope represents the frequency of the input signal. I am sure people on here are familiar with the counters made by Pendulum, and I have to confess that their marketing material was helpful in putting this thing together. Since the hardware is true zero dead time, the final capabilities of this counter are determined by software. At the moment I can simultaneously display the input at multiple gate times (see the attached screen shot). For gate times over 1 second I have the option to use overlapping gates, so that the display gets updated every second. Because there is no dead time I can also calculate Allan Deviation. The two displays at the bottom of the page show both normal and overlapping Allan deviation at tau=10s. I am still working on the software to do this at multiple tau in real time and display it as a graph and a table. So, after this lengthy introduction here is my request for some assistance. Is there somebody on the list who can assist me in verifying the performance of this frequency counter? Ideally somebody with access to two highly stable and known frequency sources. I can send the hardware by mail, but if there happens to be somebody with this kind of gear not too far from where I am (50 north of London) I will travel. In exchange you get to keep the hardware and will be supplied with whatever software I come up with. Thanks in advance and regards, Gerard, PG5G Are you calculating ADEV and MDEV using the slopes determined by the regression fit? If so, what you calculate isn't ADEV or MDEV. You need to use the raw timestamps taken at a rate of 5000/sec directly to produce estimates of ADEV, MDEV. What is the resolution of the TDC? Bruce ___ 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] thunderbolt fault
Hi What I'm talking about here is a common mode choke on the +12 volt supply. They are pretty common items. Just about every TV or commercial switcher has one on the power line. Some switchers have them on the outputs as well. Two independent windings are put on the same core. The DC current / flux generated in one cancels the magnetizing flux from the other. That keeps the core from saturating. Thus you can get a lot of inductance in a small package. With a differential mode choke the thing that makes them *big* is core saturation. The obvious gotcha is that they will indeed saturate with very high levels of common mode noise. That's unlikely to be an issue here. The simple reason it would apply here is your earlier comment that the +12 is the supply to worry about. If the +12 and +5 are garden variety that would suggest a higher grade supply for the +12 source. As long as the currents are balanced, a common mode choke can be useful. No choke is going to help with DC regulation at the levels we are talking about here. What a choke is going to help with is audio and RF crud on the supply. Things like an external three terminal regulator will help with differential noise on the supply. The same is true of bypass caps. What they will not help with is common mode noise. There are some exotic current source setups that will help with common mode, but a choke is normally a lot cheaper (and in most cases better approach). At some point in the audio range the isolation provided by most regulators drops off. By the time you get to 100 KHz it's rare to find one that is doing a lot more than the bypass capacitors alone would do. If you know that the +12 is sensitive, doing a broad band isolation may indeed help things. Chokes of some sort are likely to be part of what you grab for the task. I've seen designs that go quite a way down the differential filter road when the real issue was common mode. There's no reason to throw away anything else here. It's just one more thing to consider adding to the design. Depending on exactly how things are or aren't set up it may or may not help. Bob On Feb 26, 2010, at 10:44 PM, WarrenS wrote: I don't know of any reasonable inductor thing that is useful to reduce High current ripple PS ripple. There where inductors, of the small bread box size, used in very early tube radios, But that was mostly just for low current B+ voltages. Do you have a standard part in mind that will reduce 60 and 120Hz line voltage ripple by 20 dB or more at 1/2 amp rating, AND that does not hurt the voltage regulation with changing currents? What about one to reduce the DC voltage variations? Your ground loop comment, sounds like you are talking about isolating the 10 MHz Osc ground to reduce ground loop problems and your comments are NOT about reducing the +12 volt PS ripple. If so, Yea good idea, But BIG difference. As often happens on these post, there is misunderstandings somewhere and they tend to get way off the point, so have to go now and let others take the torch. Original question was, Is the Tbolt's -12 volt supply sensitive or critical. SIMPLE answer, NO, just use a little common sense with it. Have fun ws ** Hi It's pretty easy to get a common mode choke that will indeed break up 120 Hz ground loops. Often they are very low impedance. With most supplies the rectified line is what's coming through. Bob ** On Feb 26, 2010, at 10:10 PM, WarrenS wrote: Common mode choke filter does not get ride of LINE NOISE on the +12 V or LINE VOLTAGE sensitivities..., Please explain how a common mode choke on the +12 and ground does nothing to help keep the supply clean. What size is your common mode choke filter? To have any effect on 60 Hz PS ripple it would need to bigger than a (small) bread box . And to help reduce DC type line voltage variations it would need to be bigger than a planet. (yea, Earth size) Common mode filters are for HI freq, not 60 Hz OR DC. But then, you already know that so I do not know why your comment??? ws * Hi Please explain how a common mode choke on the +12 and ground does nothing to help keep the supply clean. Bob * On Feb 26, 2010, at 9:57 PM, WarrenS wrote: Lots of questions Same Simple answer. Make the +12 volts is as good as you can get it, For the rest any general purpose PS works fine. And a Common mode choke filter does not get ride of line noise on the +12 V or Line voltage sensitivities, both are important on the +12V ws Hi Depending on the supply setup, a common mode choke might also be a good idea. The +12 runs the OCXO, so it's going to have an impact. What about the +5 Volts? Obviously it needs to be crud free. Gross changes will impact the temperature of the unit. What about small changes? Is it running the maser reference
Re: [time-nuts] My DIY frequency counter and a request for help
Gerard you have some great comments already and welcome back to the electronics hobby. A couple of things. Curious about whats on the board etc. Here would be my thoughts. If the same 10 MC signal thats the reference is also the input. Then any funny numbers are the process leftovers or jitter. I think this would also help you find the max resolution quickly. Once you introduce external signals it becomes more difficult to understand whats happening. I built a LORAN C simulator driven by a Rb reference. When I drive the austron 2100 with the same reference the austron ultimately settles at its max resolution of 1 E-13. Very interesting first project you clearly have a good background in applied electronics On Sat, Feb 27, 2010 at 7:36 AM, Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: Gerard PG5G wrote: Hello all, First post here, so I'll start with a quick introduction. I trained as an electronic engineer but don't work in that field any more, which has given me the appetite back to do some electronic engineering as a hobby. I have been a licensed ham for over 25 years (more than 60% of my life I realised the other day) and used to be rather active on HF as PA3DQW. At the moment I live in the UK where I am licensed as M0AIU. I recently designed and build a frequency counter and I need some help with verifying its performance. I believe it gives me 11 digits in 1 second. I say believe because I have not got the hardware to verify this. At the moment my assumption is based on calculations and limited testing with the equipment available to me. My counter is a continuous time stamping reciprocal counter. I implemented this as a USB powered device, with the hardware taking the time stamps and sending it over USB to a windows PC. Some software written in C++ takes care of analysing the data. The hardware takes 5000 time stamps per second using a high speed TDC. The hardware is a single PCB measuring about 50 by 80 mm. it requires an external 10MHz reference and apart from using this as the time base it also uses this for self-calibration of the TDC. The unit requires no further calibration. The PC software takes these time stamps and the associated counts and uses regression to calculate the slope. This slope represents the frequency of the input signal. I am sure people on here are familiar with the counters made by Pendulum, and I have to confess that their marketing material was helpful in putting this thing together. Since the hardware is true zero dead time, the final capabilities of this counter are determined by software. At the moment I can simultaneously display the input at multiple gate times (see the attached screen shot). For gate times over 1 second I have the option to use overlapping gates, so that the display gets updated every second. Because there is no dead time I can also calculate Allan Deviation. The two displays at the bottom of the page show both normal and overlapping Allan deviation at tau=10s. I am still working on the software to do this at multiple tau in real time and display it as a graph and a table. So, after this lengthy introduction here is my request for some assistance. Is there somebody on the list who can assist me in verifying the performance of this frequency counter? Ideally somebody with access to two highly stable and known frequency sources. I can send the hardware by mail, but if there happens to be somebody with this kind of gear not too far from where I am (50 north of London) I will travel. In exchange you get to keep the hardware and will be supplied with whatever software I come up with. Thanks in advance and regards, Gerard, PG5G Are you calculating ADEV and MDEV using the slopes determined by the regression fit? If so, what you calculate isn't ADEV or MDEV. You need to use the raw timestamps taken at a rate of 5000/sec directly to produce estimates of ADEV, MDEV. What is the resolution of the TDC? Bruce ___ 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] hp 5061a probabily A9 fault
now all seeme to work properly except probalily A9 . with loop open , at J6 of A7 board I will have minimum 137Hz signal when the frequency is exatly , but the signal grow if I move osc frequency , this should be indicate all work good . the problem is when I close the loop , the frequency shift a little and the 137Uz signal grow . maybe a problem in A9 board . I tried to made adjustement of amplifier zero , but there are somthing wrong , I do not have zero but 80mv . phase detector zero adjustement is ok i read zero. any seggestion will be appreciated. i5uxj ___ 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] DMTD Mixer Terminations
I am in the process of designing a DMTD system. As an experiment to do basic measurements on the chosen mixer, I used a capacitor (0.01 uF) in series to ground with a 47 ohm metal film resistor. Where the capacitor and resistor meets, another resistor is attached (390 ohms) that goes to ground. The idea is to provide a 50 ohm termination at 20 Mhz and a lighter termination at audio frequencies. I seen this is a NBS note and I can say, its a starting point for my experiments. This (my) system is designed for 10 Mhz, using a 10 hertz beat. A schematic is attached of what I am experimenting with at the moment. A HP5370B is the recording instrument. The noise floor from 1 days observations show 2x10-11 at 0.1 seconds, 2x10-12 at 1 sec, 5x10-13 at 10 sec, 6x10-14 at 100 sec, 7x10-15 at 1000 sec, and 7x10-16 at 10,000 secs. It will be interesting when the project is completed to see how much improvement there will be. As I understand (or learning..) mixer performance is the key to the DMTD system. It occurs to me that maybe a capacitor designed for 50 ohms at 20 mhz may be a better termination (for the IF port) for this mixer. A 16 pF capacitor is 50 ohms at 20 mhz, and for comparison at 10 hertz, it would be 100 meg-ohms, which would give maximum amplitude at 10 hertz. As I understand, a capacitor terminated mixer will give a triangle wave output, which is very beneficial to the design - as the end result is to get maximum slope out of the mixer. I would say, unqualified as I am, the capacitor termination matches the 20 mhz signal, and helps attenuates the harmonics of the mixer, and has no , or very little effect on the audio frequencies that we are interested in. And saying/rambling on... that if maximum slope is needed, its needed on the 10 hertz beat signal - so maybe a capacitive termination on the 10 hertz signal only and something resistive on the 20 mhz signalanother idea use the 16 pF direct off the mixer, then a series resistor for isolation and then a large capacitor on the 10 hertz beat for maximum slope. At the present, I am awaiting parts to build a low noise preamp base on the THAT1512 so I can make better measurements on the mixer. Bruce has provided a lot of good suggestions and helpful comments on my project and Ulrich has provided me quite a bit of user support on his program, Plotter. Thanks to all. Comments ? Brian KD4FM DMTD_Plans.pdf Description: Adobe PDF document ___ 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] DMTD Mixer Terminations
Hi A couple of things to try: Just drop a 0.01 uf to ground directly on the output of the mixer. Take the 390 to ground up to 3.9K ohms. Depending on your mixer either / both may help or hurt. You also may be able to run slightly more power into the mixer. More power may also smoke the mixer. Bob On Feb 27, 2010, at 12:41 PM, Brian Kirby wrote: I am in the process of designing a DMTD system. As an experiment to do basic measurements on the chosen mixer, I used a capacitor (0.01 uF) in series to ground with a 47 ohm metal film resistor. Where the capacitor and resistor meets, another resistor is attached (390 ohms) that goes to ground. The idea is to provide a 50 ohm termination at 20 Mhz and a lighter termination at audio frequencies. I seen this is a NBS note and I can say, its a starting point for my experiments. This (my) system is designed for 10 Mhz, using a 10 hertz beat. A schematic is attached of what I am experimenting with at the moment. A HP5370B is the recording instrument. The noise floor from 1 days observations show 2x10-11 at 0.1 seconds, 2x10-12 at 1 sec, 5x10-13 at 10 sec, 6x10-14 at 100 sec, 7x10-15 at 1000 sec, and 7x10-16 at 10,000 secs. It will be interesting when the project is completed to see how much improvement there will be. As I understand (or learning..) mixer performance is the key to the DMTD system. It occurs to me that maybe a capacitor designed for 50 ohms at 20 mhz may be a better termination (for the IF port) for this mixer. A 16 pF capacitor is 50 ohms at 20 mhz, and for comparison at 10 hertz, it would be 100 meg-ohms, which would give maximum amplitude at 10 hertz. As I understand, a capacitor terminated mixer will give a triangle wave output, which is very beneficial to the design - as the end result is to get maximum slope out of the mixer. I would say, unqualified as I am, the capacitor termination matches the 20 mhz signal, and helps attenuates the harmonics of the mixer, and has no , or very little effect on the audio frequencies that we are interested in. And saying/rambling on... that if maximum slope is needed, its needed on the 10 hertz beat signal - so maybe a capacitive termination on the 10 hertz signal only and something resistive on the 20 mhz signalanother idea use the 16 pF direct off the mixer, then a series resistor for isolation and then a large capacitor on the 10 hertz beat for maximum slope. At the present, I am awaiting parts to build a low noise preamp base on the THAT1512 so I can make better measurements on the mixer. Bruce has provided a lot of good suggestions and helpful comments on my project and Ulrich has provided me quite a bit of user support on his program, Plotter. Thanks to all. Comments ? Brian KD4FM DMTD_Plans.pdf___ 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] thunderbolt fault
Simplified summery of all the past N.S. in this thread The Tbolt needs a very clean and stable +12 volt supply to get the best possible performance. The -12 +5 supplies are not very critical. For the +12 volt supply, use one as good as you can, For the -12V (-8 to -13) +5V (+-5%) power, Most any general purpose Regulated supply will work fine. To help explain in more detail, Bob added: A common mode choke might also be a good idea, [to use in several places, to clean up and remove high freq and audio noise caused by switcher etc.] WarrenS added: TRUE, BUT A Common mode choke filter does not remove 60 or 120 Hz line freq ripple on the +12 V, nor does it help with voltage variations caused by Line voltage sensitivities. For that, using a +15 volt supply feeding a well heatsinked, 12V three terminal regulator is one good way to keep the Line freq ripple and voltage variations out of the +12V. [The 15 volts has to be clean with no High freq junk, OR some will get thru the post regulator.] ws * Hi What I'm talking about here is a common mode choke on the +12 volt supply. They are pretty common items. Just about every TV or commercial switcher has one on the power line. Some switchers have them on the outputs as well. Two independent windings are put on the same core. The DC current / flux generated in one cancels the magnetizing flux from the other. That keeps the core from saturating. Thus you can get a lot of inductance in a small package. With a differential mode choke the thing that makes them *big* is core saturation. The obvious gotcha is that they will indeed saturate with very high levels of common mode noise. That's unlikely to be an issue here. The simple reason it would apply here is your earlier comment that the +12 is the supply to worry about. If the +12 and +5 are garden variety that would suggest a higher grade supply for the +12 source. As long as the currents are balanced, a common mode choke can be useful. No choke is going to help with DC regulation at the levels we are talking about here. What a choke is going to help with is audio and RF crud on the supply. Things like an external three terminal regulator will help with differential noise on the supply. The same is true of bypass caps. What they will not help with is common mode noise. There are some exotic current source setups that will help with common mode, but a choke is normally a lot cheaper (and in most cases better approach). At some point in the audio range the isolation provided by most regulators drops off. By the time you get to 100 KHz it's rare to find one that is doing a lot more than the bypass capacitors alone would do. If you know that the +12 is sensitive, doing a broad band isolation may indeed help things. Chokes of some sort are likely to be part of what you grab for the task. I've seen designs that go quite a way down the differential filter road when the real issue was common mode. There's no reason to throw away anything else here. It's just one more thing to consider adding to the design. Depending on exactly how things are or aren't set up it may or may not help. Bob On Feb 26, 2010, at 10:44 PM, WarrenS wrote: I don't know of any reasonable inductor thing that is useful to reduce High current ripple PS ripple. There where inductors, of the small bread box size, used in very early tube radios, But that was mostly just for low current B+ voltages. Do you have a standard part in mind that will reduce 60 and 120Hz line voltage ripple by 20 dB or more at 1/2 amp rating, AND that does not hurt the voltage regulation with changing currents? What about one to reduce the DC voltage variations? Your ground loop comment, sounds like you are talking about isolating the 10 MHz Osc ground to reduce ground loop problems and your comments are NOT about reducing the +12 volt PS ripple. If so, Yea good idea, But BIG difference. As often happens on these post, there is misunderstandings somewhere and they tend to get way off the point, so have to go now and let others take the torch. Original question was, Is the Tbolt's -12 volt supply sensitive or critical. SIMPLE answer, NO, just use a little common sense with it. Have fun ws ** Hi It's pretty easy to get a common mode choke that will indeed break up 120 Hz ground loops. Often they are very low impedance. With most supplies the rectified line is what's coming through. Bob ** On Feb 26, 2010, at 10:10 PM, WarrenS wrote: Common mode choke filter does not get ride of LINE NOISE on the +12 V or LINE VOLTAGE sensitivities..., Please explain how a common mode choke on the +12 and ground does nothing to help keep the supply clean. What size is your common mode choke filter? To have any effect on 60 Hz PS ripple it would need to bigger than a (small) bread box . And to help reduce DC type line voltage variations it would need to be
Re: [time-nuts] DMTD Mixer Terminations
Brian Kirby wrote: I am in the process of designing a DMTD system. As an experiment to do basic measurements on the chosen mixer, I used a capacitor (0.01 uF) in series to ground with a 47 ohm metal film resistor. Where the capacitor and resistor meets, another resistor is attached (390 ohms) that goes to ground. The idea is to provide a 50 ohm termination at 20 Mhz and a lighter termination at audio frequencies. I seen this is a NBS note and I can say, its a starting point for my experiments. You will need a bit more filtering of the mixer IF output, or signal rectification effects in the bipolar opamp may be an issue. The amplitude of the sum frequency component seen by the opamp input needs to be reduced to a value such that the effect of signal rectification by the opamp input stage is insignificant. This (my) system is designed for 10 Mhz, using a 10 hertz beat. A schematic is attached of what I am experimenting with at the moment. A HP5370B is the recording instrument. The noise floor from 1 days observations show 2x10-11 at 0.1 seconds, 2x10-12 at 1 sec, 5x10-13 at 10 sec, 6x10-14 at 100 sec, 7x10-15 at 1000 sec, and 7x10-16 at 10,000 secs. It will be interesting when the project is completed to see how much improvement there will be. As I understand (or learning..) mixer performance is the key to the DMTD system. It occurs to me that maybe a capacitor designed for 50 ohms at 20 mhz may be a better termination (for the IF port) for this mixer. A 16 pF capacitor is 50 ohms at 20 mhz, and for comparison at 10 hertz, it would be 100 meg-ohms, which would give maximum amplitude at 10 hertz. As I understand, a capacitor terminated mixer will give a triangle wave output, which is very beneficial to the design - as the end result is to get maximum slope out of the mixer. I would say, unqualified as I am, the capacitor termination matches the 20 mhz signal, and helps attenuates the harmonics of the mixer, and has no , or very little effect on the audio frequencies that we are interested in. Whilst in narrowband systems (a DMTD is a narrow band system) reactive termination of the mixer/phase detector RF port will reduce the noise, the idea is to reflect all of the sum frequency component back into the mixer. This can be done using a capacitive termination where the impedance of the capacitor is low at the (20MHz) sum frequency. The capacitor impedance should be high at the (10Hz) difference frequency to avoid attenuating the difference frequency component. Using a capacitor with a 50 ohm reactance at the sum frequency will not reflect all of the sum frequency back into the mixer. Note with saturated mixer input ports capacitive termination as outlined above of the IF port will not produce a triangular beat frequency waveform. The waveform should be quasi trapezoidal with rounded peaks. The slew rate at the zero crossing will be increased and the noise to slope ration improved over that achieved with a more conventional termination. And saying/rambling on... that if maximum slope is needed, its needed on the 10 hertz beat signal - so maybe a capacitive termination on the 10 hertz signal only and something resistive on the 20 mhz signalanother idea use the 16 pF direct off the mixer, then a series resistor for isolation and then a large capacitor on the 10 hertz beat for maximum slope. There are a series of NIST papers that show the effect of the IF port termination on the noise and beat frequency waveform. Since its very easy to measure the beat frequency waveform slope and noise at the zero crossing its probably better to calibrate your speculations with actual measurements. At the present, I am awaiting parts to build a low noise preamp base on the THAT1512 so I can make better measurements on the mixer. Bruce has provided a lot of good suggestions and helpful comments on my project and Ulrich has provided me quite a bit of user support on his program, Plotter. Thanks to all. Comments ? Brian KD4FM Bruce ___ 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] Rack-mounting an LPRO?
Dear time-nuts, I've just bought a used LPRO-101 which should get a permanent home inside an instrument rack. I've also found a very nice 1U high metal case, and a fitting 24V 1U power supply - leaving plenty of room for a distribution amp and a microcontroller to log things like lamp and Xtal voltage. The rackmount enclosure is 1U high, and seems to be made of 1mm thick galvanized steel. Would that make a good enough baseplate for the LPRO? Would I need to do anything to improve the thermal contact between the rubidium oscillator and the baseplate, and if so, any recommendations on what to use there? The LPRO User's guide and integration guidelines recommend 2degC/W thermal resistance (for up to 50degC ambient), and using some special thermal tape that will probably be very hard to get at these days. If any of you has already put something like this together, I'd be very interested in your suggestions. Regards, Paul Boven - PE1NUT ___ 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] Rack-mounting an LPRO?
Hi 1mm is pretty thin for a heat sink made of steel. You might consider an aluminum plate around 4 mm thick and the length and width of the case to act as a heat spreader. The LPRO probably already has the tape on the bottom of it. The tape may be in fine shape. If it's not, scrape off what remains and use a normal thermal grease (heat sink compound) between the bottom of the LPRO and the heat spreader. You also should fill the gap between the heat spreader and the steel case with something. I would use some sort of thermaly conductive epoxy. You don't need the silver loaded stuff. Ceramic loaded should be ok. Bob On Feb 27, 2010, at 5:30 PM, Paul Boven wrote: Dear time-nuts, I've just bought a used LPRO-101 which should get a permanent home inside an instrument rack. I've also found a very nice 1U high metal case, and a fitting 24V 1U power supply - leaving plenty of room for a distribution amp and a microcontroller to log things like lamp and Xtal voltage. The rackmount enclosure is 1U high, and seems to be made of 1mm thick galvanized steel. Would that make a good enough baseplate for the LPRO? Would I need to do anything to improve the thermal contact between the rubidium oscillator and the baseplate, and if so, any recommendations on what to use there? The LPRO User's guide and integration guidelines recommend 2degC/W thermal resistance (for up to 50degC ambient), and using some special thermal tape that will probably be very hard to get at these days. If any of you has already put something like this together, I'd be very interested in your suggestions. Regards, Paul Boven - PE1NUT ___ 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] DMTD Mixer Terminations
Hi Assuming that the junction of the back to back diodes goes trough a chunk of coax to get to the counter: You are forming a low pass filter with the 10K resistor and the coax capacitance. The LT1037 is quite happy driving a 600 ohm load. You could easily drop the impedance at that point below 300 ohms. That should give you a faster edge into the counter. You also should check the slew rate performance of the 1037. You don't want the op amp to be slew rate limited. Bob On Feb 27, 2010, at 12:41 PM, Brian Kirby wrote: I am in the process of designing a DMTD system. As an experiment to do basic measurements on the chosen mixer, I used a capacitor (0.01 uF) in series to ground with a 47 ohm metal film resistor. Where the capacitor and resistor meets, another resistor is attached (390 ohms) that goes to ground. The idea is to provide a 50 ohm termination at 20 Mhz and a lighter termination at audio frequencies. I seen this is a NBS note and I can say, its a starting point for my experiments. This (my) system is designed for 10 Mhz, using a 10 hertz beat. A schematic is attached of what I am experimenting with at the moment. A HP5370B is the recording instrument. The noise floor from 1 days observations show 2x10-11 at 0.1 seconds, 2x10-12 at 1 sec, 5x10-13 at 10 sec, 6x10-14 at 100 sec, 7x10-15 at 1000 sec, and 7x10-16 at 10,000 secs. It will be interesting when the project is completed to see how much improvement there will be. As I understand (or learning..) mixer performance is the key to the DMTD system. It occurs to me that maybe a capacitor designed for 50 ohms at 20 mhz may be a better termination (for the IF port) for this mixer. A 16 pF capacitor is 50 ohms at 20 mhz, and for comparison at 10 hertz, it would be 100 meg-ohms, which would give maximum amplitude at 10 hertz. As I understand, a capacitor terminated mixer will give a triangle wave output, which is very beneficial to the design - as the end result is to get maximum slope out of the mixer. I would say, unqualified as I am, the capacitor termination matches the 20 mhz signal, and helps attenuates the harmonics of the mixer, and has no , or very little effect on the audio frequencies that we are interested in. And saying/rambling on... that if maximum slope is needed, its needed on the 10 hertz beat signal - so maybe a capacitive termination on the 10 hertz signal only and something resistive on the 20 mhz signalanother idea use the 16 pF direct off the mixer, then a series resistor for isolation and then a large capacitor on the 10 hertz beat for maximum slope. At the present, I am awaiting parts to build a low noise preamp base on the THAT1512 so I can make better measurements on the mixer. Bruce has provided a lot of good suggestions and helpful comments on my project and Ulrich has provided me quite a bit of user support on his program, Plotter. Thanks to all. Comments ? Brian KD4FM DMTD_Plans.pdf___ 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] DMTD Mixer Terminations
The LT1037 is shown with a gain of ~1690x, if this amplifier is used to amplify the beat frequency signal, it will saturate. Opamp recovery from saturation is poorly documented and may be very slow. It would be better to use some diodes in the amplifier feedback network to limit the large signal gain to 5x (so that the LT1037 remains stable as it isn't unity gain stable). This will ensure a somewhat faster recovery from overload as the LT1037 then avoids saturation and the opamp input stage remains in the linear region. Bruce Bob Camp wrote: Hi Assuming that the junction of the back to back diodes goes trough a chunk of coax to get to the counter: You are forming a low pass filter with the 10K resistor and the coax capacitance. The LT1037 is quite happy driving a 600 ohm load. You could easily drop the impedance at that point below 300 ohms. That should give you a faster edge into the counter. You also should check the slew rate performance of the 1037. You don't want the op amp to be slew rate limited. Bob On Feb 27, 2010, at 12:41 PM, Brian Kirby wrote: I am in the process of designing a DMTD system. As an experiment to do basic measurements on the chosen mixer, I used a capacitor (0.01 uF) in series to ground with a 47 ohm metal film resistor. Where the capacitor and resistor meets, another resistor is attached (390 ohms) that goes to ground. The idea is to provide a 50 ohm termination at 20 Mhz and a lighter termination at audio frequencies. I seen this is a NBS note and I can say, its a starting point for my experiments. This (my) system is designed for 10 Mhz, using a 10 hertz beat. A schematic is attached of what I am experimenting with at the moment. A HP5370B is the recording instrument. The noise floor from 1 days observations show 2x10-11 at 0.1 seconds, 2x10-12 at 1 sec, 5x10-13 at 10 sec, 6x10-14 at 100 sec, 7x10-15 at 1000 sec, and 7x10-16 at 10,000 secs. It will be interesting when the project is completed to see how much improvement there will be. As I understand (or learning..) mixer performance is the key to the DMTD system. It occurs to me that maybe a capacitor designed for 50 ohms at 20 mhz may be a better termination (for the IF port) for this mixer. A 16 pF capacitor is 50 ohms at 20 mhz, and for comparison at 10 hertz, it would be 100 meg-ohms, which would give maximum amplitude at 10 hertz. As I understand, a capacitor terminated mixer will give a triangle wave output, which is very beneficial to the design - as the end result is to get maximum slope out of the mixer. I would say, unqualified as I am, the capacitor termination matches the 20 mhz signal, and helps attenuates the harmonics of the mixer, and has no , or very little effect on the audio frequencies that we are interested in. And saying/rambling on... that if maximum slope is needed, its needed on the 10 hertz beat signal - so maybe a capacitive termination on the 10 hertz signal only and something resistive on the 20 mhz signalanother idea use the 16 pF direct off the mixer, then a series resistor for isolation and then a large capacitor on the 10 hertz beat for maximum slope. At the present, I am awaiting parts to build a low noise preamp base on the THAT1512 so I can make better measurements on the mixer. Bruce has provided a lot of good suggestions and helpful comments on my project and Ulrich has provided me quite a bit of user support on his program, Plotter. Thanks to all. Comments ? Brian KD4FM DMTD_Plans.pdf___ 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] Rack-mounting an LPRO?
I agree that thats not really an effective heat sink. On Sat, Feb 27, 2010 at 6:12 PM, Bob Camp li...@rtty.us wrote: Hi 1mm is pretty thin for a heat sink made of steel. You might consider an aluminum plate around 4 mm thick and the length and width of the case to act as a heat spreader. The LPRO probably already has the tape on the bottom of it. The tape may be in fine shape. If it's not, scrape off what remains and use a normal thermal grease (heat sink compound) between the bottom of the LPRO and the heat spreader. You also should fill the gap between the heat spreader and the steel case with something. I would use some sort of thermaly conductive epoxy. You don't need the silver loaded stuff. Ceramic loaded should be ok. Bob On Feb 27, 2010, at 5:30 PM, Paul Boven wrote: Dear time-nuts, I've just bought a used LPRO-101 which should get a permanent home inside an instrument rack. I've also found a very nice 1U high metal case, and a fitting 24V 1U power supply - leaving plenty of room for a distribution amp and a microcontroller to log things like lamp and Xtal voltage. The rackmount enclosure is 1U high, and seems to be made of 1mm thick galvanized steel. Would that make a good enough baseplate for the LPRO? Would I need to do anything to improve the thermal contact between the rubidium oscillator and the baseplate, and if so, any recommendations on what to use there? The LPRO User's guide and integration guidelines recommend 2degC/W thermal resistance (for up to 50degC ambient), and using some special thermal tape that will probably be very hard to get at these days. If any of you has already put something like this together, I'd be very interested in your suggestions. Regards, Paul Boven - PE1NUT ___ 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] Rack-mounting an LPRO?
For operation at ambient temperatures up to 50C the manual states that a baseplate heatsink with a thermal resistance of 2C/W or lower is required. Bruce paul swed wrote: I agree that thats not really an effective heat sink. On Sat, Feb 27, 2010 at 6:12 PM, Bob Campli...@rtty.us wrote: Hi 1mm is pretty thin for a heat sink made of steel. You might consider an aluminum plate around 4 mm thick and the length and width of the case to act as a heat spreader. The LPRO probably already has the tape on the bottom of it. The tape may be in fine shape. If it's not, scrape off what remains and use a normal thermal grease (heat sink compound) between the bottom of the LPRO and the heat spreader. You also should fill the gap between the heat spreader and the steel case with something. I would use some sort of thermaly conductive epoxy. You don't need the silver loaded stuff. Ceramic loaded should be ok. Bob On Feb 27, 2010, at 5:30 PM, Paul Boven wrote: Dear time-nuts, I've just bought a used LPRO-101 which should get a permanent home inside an instrument rack. I've also found a very nice 1U high metal case, and a fitting 24V 1U power supply - leaving plenty of room for a distribution amp and a microcontroller to log things like lamp and Xtal voltage. The rackmount enclosure is 1U high, and seems to be made of 1mm thick galvanized steel. Would that make a good enough baseplate for the LPRO? Would I need to do anything to improve the thermal contact between the rubidium oscillator and the baseplate, and if so, any recommendations on what to use there? The LPRO User's guide and integration guidelines recommend 2degC/W thermal resistance (for up to 50degC ambient), and using some special thermal tape that will probably be very hard to get at these days. If any of you has already put something like this together, I'd be very interested in your suggestions. Regards, Paul Boven - PE1NUT ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Rack-mounting an LPRO?
Hi Another option for cooling the LPRO would be a fan in combination with a heat sink.. That's not my favorite way to go, but it should take care of the cooling. Bob On Feb 27, 2010, at 6:51 PM, Bruce Griffiths wrote: For operation at ambient temperatures up to 50C the manual states that a baseplate heatsink with a thermal resistance of 2C/W or lower is required. Bruce paul swed wrote: I agree that thats not really an effective heat sink. On Sat, Feb 27, 2010 at 6:12 PM, Bob Campli...@rtty.us wrote: Hi 1mm is pretty thin for a heat sink made of steel. You might consider an aluminum plate around 4 mm thick and the length and width of the case to act as a heat spreader. The LPRO probably already has the tape on the bottom of it. The tape may be in fine shape. If it's not, scrape off what remains and use a normal thermal grease (heat sink compound) between the bottom of the LPRO and the heat spreader. You also should fill the gap between the heat spreader and the steel case with something. I would use some sort of thermaly conductive epoxy. You don't need the silver loaded stuff. Ceramic loaded should be ok. Bob On Feb 27, 2010, at 5:30 PM, Paul Boven wrote: Dear time-nuts, I've just bought a used LPRO-101 which should get a permanent home inside an instrument rack. I've also found a very nice 1U high metal case, and a fitting 24V 1U power supply - leaving plenty of room for a distribution amp and a microcontroller to log things like lamp and Xtal voltage. The rackmount enclosure is 1U high, and seems to be made of 1mm thick galvanized steel. Would that make a good enough baseplate for the LPRO? Would I need to do anything to improve the thermal contact between the rubidium oscillator and the baseplate, and if so, any recommendations on what to use there? The LPRO User's guide and integration guidelines recommend 2degC/W thermal resistance (for up to 50degC ambient), and using some special thermal tape that will probably be very hard to get at these days. If any of you has already put something like this together, I'd be very interested in your suggestions. Regards, Paul Boven - PE1NUT ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] DMTD Mixer Terminations
Hi The gotcha here is that saturation / slew limiting is one of the few things that will give you *better* data than the oscillators are really doing. Most error sources have the nice property of making things worse. Bob On Feb 27, 2010, at 6:40 PM, Bruce Griffiths wrote: The LT1037 is shown with a gain of ~1690x, if this amplifier is used to amplify the beat frequency signal, it will saturate. Opamp recovery from saturation is poorly documented and may be very slow. It would be better to use some diodes in the amplifier feedback network to limit the large signal gain to 5x (so that the LT1037 remains stable as it isn't unity gain stable). This will ensure a somewhat faster recovery from overload as the LT1037 then avoids saturation and the opamp input stage remains in the linear region. Bruce Bob Camp wrote: Hi Assuming that the junction of the back to back diodes goes trough a chunk of coax to get to the counter: You are forming a low pass filter with the 10K resistor and the coax capacitance. The LT1037 is quite happy driving a 600 ohm load. You could easily drop the impedance at that point below 300 ohms. That should give you a faster edge into the counter. You also should check the slew rate performance of the 1037. You don't want the op amp to be slew rate limited. Bob On Feb 27, 2010, at 12:41 PM, Brian Kirby wrote: I am in the process of designing a DMTD system. As an experiment to do basic measurements on the chosen mixer, I used a capacitor (0.01 uF) in series to ground with a 47 ohm metal film resistor. Where the capacitor and resistor meets, another resistor is attached (390 ohms) that goes to ground. The idea is to provide a 50 ohm termination at 20 Mhz and a lighter termination at audio frequencies. I seen this is a NBS note and I can say, its a starting point for my experiments. This (my) system is designed for 10 Mhz, using a 10 hertz beat. A schematic is attached of what I am experimenting with at the moment. A HP5370B is the recording instrument. The noise floor from 1 days observations show 2x10-11 at 0.1 seconds, 2x10-12 at 1 sec, 5x10-13 at 10 sec, 6x10-14 at 100 sec, 7x10-15 at 1000 sec, and 7x10-16 at 10,000 secs. It will be interesting when the project is completed to see how much improvement there will be. As I understand (or learning..) mixer performance is the key to the DMTD system. It occurs to me that maybe a capacitor designed for 50 ohms at 20 mhz may be a better termination (for the IF port) for this mixer. A 16 pF capacitor is 50 ohms at 20 mhz, and for comparison at 10 hertz, it would be 100 meg-ohms, which would give maximum amplitude at 10 hertz. As I understand, a capacitor terminated mixer will give a triangle wave output, which is very beneficial to the design - as the end result is to get maximum slope out of the mixer. I would say, unqualified as I am, the capacitor termination matches the 20 mhz signal, and helps attenuates the harmonics of the mixer, and has no , or very little effect on the audio frequencies that we are interested in. And saying/rambling on... that if maximum slope is needed, its needed on the 10 hertz beat signal - so maybe a capacitive termination on the 10 hertz signal only and something resistive on the 20 mhz signalanother idea use the 16 pF direct off the mixer, then a series resistor for isolation and then a large capacitor on the 10 hertz beat for maximum slope. At the present, I am awaiting parts to build a low noise preamp base on the THAT1512 so I can make better measurements on the mixer. Bruce has provided a lot of good suggestions and helpful comments on my project and Ulrich has provided me quite a bit of user support on his program, Plotter. Thanks to all. Comments ? Brian KD4FM DMTD_Plans.pdf___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Achieving maximum performance when driving 5370A/B inputs
At 07:01 PM 2/27/2010, Bruce Griffiths wrote... For the 5370A attenuating the 5V CMOS signal to a 1V... For the 5370A attenuating the 5V CMOS signal to a 2V... ITYM 5370B for the second part. ___ 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] Achieving maximum performance when driving 5370A/B inputs
Oops! a small correction (2nd paragraph): For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370B attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum. An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). Thus using the PPS output (~270 ohm is series with a 5V 74AC04 output) from a Synergy evaluation board that uses an M12M or M12+ GPS timing receiver to drive the inputs (with a 0-750mV signal) of a 5370A or 5370B is well within the recommended input signal range for high performance. This avoids having to adding an external 5V 50 ohm driver that some would use. Bruce Bob Camp wrote: Hi So exactly how did you know that I bought a (cheap) 5370B a few hours ago on the e-place and was just about to ask about how best to use it. H... Bob On Feb 27, 2010, at 7:01 PM, Bruce Griffiths wrote: The attached excerpts from the 5370A and 5370B manuals indicate that for best performance, that the common practice of driving the 5370A/B 1x inputs directly from a 5V CMOS logic signal is a bad idea. For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370A attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum. An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). Bruce 5370ATriggering.png5370BTriggering.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.
Re: [time-nuts] Rack-mounting an LPRO?
What else is going to be in the rack? If your 1U enclosure is packed in tight between other devices there might be no cooling at all. You might need a fan to move some air. I don't know if you can find something like this, but I scavenged heat sinks from an old Compaq DL760 server that might fit your situation. Here's what the heat sink looks like. The aluminum plate is about 1/4 (6.4 mm) thick. Notice the heat pipes. Here's what it looks like on the LPRO. You'll have to drill holes in the plate to match the LPRO. It's not perfect, but it certainly does the job - particularly if you had a fan blowing through the fins. The total height is about 1.75 (45 mm). But remember, the more you cool the LPRO, the more power it will draw to keep itself warm so you don't want to overdo the cooling. Ed Paul Boven wrote: Dear time-nuts, I've just bought a used LPRO-101 which should get a permanent home inside an instrument rack. I've also found a very nice 1U high metal case, and a fitting 24V 1U power supply - leaving plenty of room for a distribution amp and a microcontroller to log things like lamp and Xtal voltage. The rackmount enclosure is 1U high, and seems to be made of 1mm thick galvanized steel. Would that make a good enough baseplate for the LPRO? Would I need to do anything to improve the thermal contact between the rubidium oscillator and the baseplate, and if so, any recommendations on what to use there? The LPRO User's guide and integration guidelines recommend 2degC/W thermal resistance (for up to 50degC ambient), and using some special thermal tape that will probably be very hard to get at these days. If any of you has already put something like this together, I'd be very interested in your suggestions. Regards, Paul Boven - PE1NUT ___ 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] Achieving maximum performance when driving 5370A/B inputs
Hi Which *still* carefully avoids the issue of how . Bob On Feb 27, 2010, at 8:52 PM, Bruce Griffiths wrote: Oops! a small correction (2nd paragraph): For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370B attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum. An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). Thus using the PPS output (~270 ohm is series with a 5V 74AC04 output) from a Synergy evaluation board that uses an M12M or M12+ GPS timing receiver to drive the inputs (with a 0-750mV signal) of a 5370A or 5370B is well within the recommended input signal range for high performance. This avoids having to adding an external 5V 50 ohm driver that some would use. Bruce Bob Camp wrote: Hi So exactly how did you know that I bought a (cheap) 5370B a few hours ago on the e-place and was just about to ask about how best to use it. H... Bob On Feb 27, 2010, at 7:01 PM, Bruce Griffiths wrote: The attached excerpts from the 5370A and 5370B manuals indicate that for best performance, that the common practice of driving the 5370A/B 1x inputs directly from a 5V CMOS logic signal is a bad idea. For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370A attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum. An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). Bruce 5370ATriggering.png5370BTriggering.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. ___ 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] Achieving maximum performance when driving 5370A/B inputs
Mike S wrote: At 07:01 PM 2/27/2010, Bruce Griffiths wrote... For the 5370A attenuating the 5V CMOS signal to a 1V... For the 5370A attenuating the 5V CMOS signal to a 2V... ITYM 5370B for the second part. Yes, a result of cutting and pasting. Bruce ___ 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] Rack-mounting an LPRO?
HI Running the LPRO from a supply below 19 volts is a good idea. As you raise the voltage into the unit, a lot of the energy simply goes into heat. Not a good thing when you have a marginal heatsink in the first place. Bob On Feb 27, 2010, at 8:56 PM, Ed Palmer wrote: What else is going to be in the rack? If your 1U enclosure is packed in tight between other devices there might be no cooling at all. You might need a fan to move some air. I don't know if you can find something like this, but I scavenged heat sinks from an old Compaq DL760 server that might fit your situation. Here's what the heat sink looks like. The aluminum plate is about 1/4 (6.4 mm) thick. Notice the heat pipes. Here's what it looks like on the LPRO. You'll have to drill holes in the plate to match the LPRO. It's not perfect, but it certainly does the job - particularly if you had a fan blowing through the fins. The total height is about 1.75 (45 mm). But remember, the more you cool the LPRO, the more power it will draw to keep itself warm so you don't want to overdo the cooling. Ed Paul Boven wrote: Dear time-nuts, I've just bought a used LPRO-101 which should get a permanent home inside an instrument rack. I've also found a very nice 1U high metal case, and a fitting 24V 1U power supply - leaving plenty of room for a distribution amp and a microcontroller to log things like lamp and Xtal voltage. The rackmount enclosure is 1U high, and seems to be made of 1mm thick galvanized steel. Would that make a good enough baseplate for the LPRO? Would I need to do anything to improve the thermal contact between the rubidium oscillator and the baseplate, and if so, any recommendations on what to use there? The LPRO User's guide and integration guidelines recommend 2degC/W thermal resistance (for up to 50degC ambient), and using some special thermal tape that will probably be very hard to get at these days. If any of you has already put something like this together, I'd be very interested in your suggestions. Regards, Paul Boven - PE1NUT ___ 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] Achieving maximum performance when driving 5370A/B inputs
1) One method with 5V CMOS is to add a resistive voltage divider at the CMOS driver output with a 50 ohm output impedance at the tap that drives the 5370A/B input. 2) If one has a 5V 50 ohm driver (eg Thunderbolt PPS output) use a 50 ohm attenuator at the 5370A/B input. For a 5370A an attenuation of at least 11dB is required. For a 5370B an attenuation of at least 3dB is required. 3) One can always use the 10x input attenuation setting built in to the 5370A/B however this reduces the signal swing to 0.5V at the trigger amplifier input (5V CMOS input). 4) Attenuate the output of the logic signal by a factor of 2 and use an npn emitter follower to drive the 50 ohm load. 5) Use 3.3V CMOS signal levels for the 5370B. 6) Use a current mode emitter or source coupled switch to drive the 5370A/B input. The switching jitter of the above drivers will be much lower than the internal noise of the 5370A/B as long as HCMOS or faster logic is employed. Bruce Bob Camp wrote: Hi Which *still* carefully avoids the issue of how . Bob On Feb 27, 2010, at 8:52 PM, Bruce Griffiths wrote: Oops! a small correction (2nd paragraph): For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370B attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum. An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). Thus using the PPS output (~270 ohm is series with a 5V 74AC04 output) from a Synergy evaluation board that uses an M12M or M12+ GPS timing receiver to drive the inputs (with a 0-750mV signal) of a 5370A or 5370B is well within the recommended input signal range for high performance. This avoids having to adding an external 5V 50 ohm driver that some would use. Bruce Bob Camp wrote: Hi So exactly how did you know that I bought a (cheap) 5370B a few hours ago on the e-place and was just about to ask about how best to use it. H... Bob On Feb 27, 2010, at 7:01 PM, Bruce Griffiths wrote: The attached excerpts from the 5370A and 5370B manuals indicate that for best performance, that the common practice of driving the 5370A/B 1x inputs directly from a 5V CMOS logic signal is a bad idea. For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370A attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum. An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). Bruce 5370ATriggering.png5370BTriggering.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. ___ 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] Achieving maximum performance when driving 5370A/B inputs
Hi AC cmos will easily drive an L pad to match a 50 ohm cable at these levels. That's true at either 3.3 or at 5.0 volts. There are a lot of cmos families out there that beat AC for speed and match the output drive capability. Bob On Feb 27, 2010, at 9:12 PM, Bruce Griffiths wrote: 1) One method with 5V CMOS is to add a resistive voltage divider at the CMOS driver output with a 50 ohm output impedance at the tap that drives the 5370A/B input. 2) If one has a 5V 50 ohm driver (eg Thunderbolt PPS output) use a 50 ohm attenuator at the 5370A/B input. For a 5370A an attenuation of at least 11dB is required. For a 5370B an attenuation of at least 3dB is required. 3) One can always use the 10x input attenuation setting built in to the 5370A/B however this reduces the signal swing to 0.5V at the trigger amplifier input (5V CMOS input). 4) Attenuate the output of the logic signal by a factor of 2 and use an npn emitter follower to drive the 50 ohm load. 5) Use 3.3V CMOS signal levels for the 5370B. 6) Use a current mode emitter or source coupled switch to drive the 5370A/B input. The switching jitter of the above drivers will be much lower than the internal noise of the 5370A/B as long as HCMOS or faster logic is employed. Bruce Bob Camp wrote: Hi Which *still* carefully avoids the issue of how . Bob On Feb 27, 2010, at 8:52 PM, Bruce Griffiths wrote: Oops! a small correction (2nd paragraph): For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370B attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum. An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). Thus using the PPS output (~270 ohm is series with a 5V 74AC04 output) from a Synergy evaluation board that uses an M12M or M12+ GPS timing receiver to drive the inputs (with a 0-750mV signal) of a 5370A or 5370B is well within the recommended input signal range for high performance. This avoids having to adding an external 5V 50 ohm driver that some would use. Bruce Bob Camp wrote: Hi So exactly how did you know that I bought a (cheap) 5370B a few hours ago on the e-place and was just about to ask about how best to use it. H... Bob On Feb 27, 2010, at 7:01 PM, Bruce Griffiths wrote: The attached excerpts from the 5370A and 5370B manuals indicate that for best performance, that the common practice of driving the 5370A/B 1x inputs directly from a 5V CMOS logic signal is a bad idea. For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370A attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum. An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). Bruce 5370ATriggering.png5370BTriggering.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. ___ 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] Achieving maximum performance when driving 5370A/B inputs
If one is feeling paranoid about ground loop noise (and wishes to avoid transformers, optoisolators , or fibre optics), etc one could always use an LVDS driver with a batter powered(?) LVDS to CMOS receiver/translator right at the 5370A/B input BNC connector. This may be useful for a DMTD system that uses a 5370A/B. Bruce Bob Camp wrote: Hi AC cmos will easily drive an L pad to match a 50 ohm cable at these levels. That's true at either 3.3 or at 5.0 volts. There are a lot of cmos families out there that beat AC for speed and match the output drive capability. Bob On Feb 27, 2010, at 9:12 PM, Bruce Griffiths wrote: 1) One method with 5V CMOS is to add a resistive voltage divider at the CMOS driver output with a 50 ohm output impedance at the tap that drives the 5370A/B input. 2) If one has a 5V 50 ohm driver (eg Thunderbolt PPS output) use a 50 ohm attenuator at the 5370A/B input. For a 5370A an attenuation of at least 11dB is required. For a 5370B an attenuation of at least 3dB is required. 3) One can always use the 10x input attenuation setting built in to the 5370A/B however this reduces the signal swing to 0.5V at the trigger amplifier input (5V CMOS input). 4) Attenuate the output of the logic signal by a factor of 2 and use an npn emitter follower to drive the 50 ohm load. 5) Use 3.3V CMOS signal levels for the 5370B. 6) Use a current mode emitter or source coupled switch to drive the 5370A/B input. The switching jitter of the above drivers will be much lower than the internal noise of the 5370A/B as long as HCMOS or faster logic is employed. Bruce Bob Camp wrote: Hi Which *still* carefully avoids the issue of how . Bob On Feb 27, 2010, at 8:52 PM, Bruce Griffiths wrote: Oops! a small correction (2nd paragraph): For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370B attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum. An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). Thus using the PPS output (~270 ohm is series with a 5V 74AC04 output) from a Synergy evaluation board that uses an M12M or M12+ GPS timing receiver to drive the inputs (with a 0-750mV signal) of a 5370A or 5370B is well within the recommended input signal range for high performance. This avoids having to adding an external 5V 50 ohm driver that some would use. Bruce Bob Camp wrote: Hi So exactly how did you know that I bought a (cheap) 5370B a few hours ago on the e-place and was just about to ask about how best to use it. H... Bob On Feb 27, 2010, at 7:01 PM, Bruce Griffiths wrote: The attached excerpts from the 5370A and 5370B manuals indicate that for best performance, that the common practice of driving the 5370A/B 1x inputs directly from a 5V CMOS logic signal is a bad idea. For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370A attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum. An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). Bruce 5370ATriggering.png5370BTriggering.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. ___ 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
Re: [time-nuts] Achieving maximum performance when driving 5370A/B inputs
Hi Gee, LVDS what an unusual approach :) It would be nice if these instruments had a balanced input. Common mode noise is indeed an issue in a lot of cases. Of course wrapping the coax headed to the counter 10X around a fairly large core can help things a bit. Bob On Feb 27, 2010, at 9:32 PM, Bruce Griffiths wrote: If one is feeling paranoid about ground loop noise (and wishes to avoid transformers, optoisolators , or fibre optics), etc one could always use an LVDS driver with a batter powered(?) LVDS to CMOS receiver/translator right at the 5370A/B input BNC connector. This may be useful for a DMTD system that uses a 5370A/B. Bruce Bob Camp wrote: Hi AC cmos will easily drive an L pad to match a 50 ohm cable at these levels. That's true at either 3.3 or at 5.0 volts. There are a lot of cmos families out there that beat AC for speed and match the output drive capability. Bob On Feb 27, 2010, at 9:12 PM, Bruce Griffiths wrote: 1) One method with 5V CMOS is to add a resistive voltage divider at the CMOS driver output with a 50 ohm output impedance at the tap that drives the 5370A/B input. 2) If one has a 5V 50 ohm driver (eg Thunderbolt PPS output) use a 50 ohm attenuator at the 5370A/B input. For a 5370A an attenuation of at least 11dB is required. For a 5370B an attenuation of at least 3dB is required. 3) One can always use the 10x input attenuation setting built in to the 5370A/B however this reduces the signal swing to 0.5V at the trigger amplifier input (5V CMOS input). 4) Attenuate the output of the logic signal by a factor of 2 and use an npn emitter follower to drive the 50 ohm load. 5) Use 3.3V CMOS signal levels for the 5370B. 6) Use a current mode emitter or source coupled switch to drive the 5370A/B input. The switching jitter of the above drivers will be much lower than the internal noise of the 5370A/B as long as HCMOS or faster logic is employed. Bruce Bob Camp wrote: Hi Which *still* carefully avoids the issue of how . Bob On Feb 27, 2010, at 8:52 PM, Bruce Griffiths wrote: Oops! a small correction (2nd paragraph): For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370B attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum. An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). Thus using the PPS output (~270 ohm is series with a 5V 74AC04 output) from a Synergy evaluation board that uses an M12M or M12+ GPS timing receiver to drive the inputs (with a 0-750mV signal) of a 5370A or 5370B is well within the recommended input signal range for high performance. This avoids having to adding an external 5V 50 ohm driver that some would use. Bruce Bob Camp wrote: Hi So exactly how did you know that I bought a (cheap) 5370B a few hours ago on the e-place and was just about to ask about how best to use it. H... Bob On Feb 27, 2010, at 7:01 PM, Bruce Griffiths wrote: The attached excerpts from the 5370A and 5370B manuals indicate that for best performance, that the common practice of driving the 5370A/B 1x inputs directly from a 5V CMOS logic signal is a bad idea. For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370A attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum. An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). Bruce 5370ATriggering.png5370BTriggering.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
Re: [time-nuts] Achieving maximum performance when driving 5370A/B inputs
In general, what about the old National damn fast and super damn fast LH0032 LH0033? I used to use a lot of those in my designs many years ago. - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 ___ 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] Achieving maximum performance when driving 5370A/B inputs
Since the input amplifier and trigger circuit are located on a small daughter board it wouldn't be too difficult to replace this with an LVDS to CML stage. The only remaining isue would be what input connector to use (twinax??, SATA??). Bruce Bob Camp wrote: Hi Gee, LVDS what an unusual approach :) It would be nice if these instruments had a balanced input. Common mode noise is indeed an issue in a lot of cases. Of course wrapping the coax headed to the counter 10X around a fairly large core can help things a bit. Bob On Feb 27, 2010, at 9:32 PM, Bruce Griffiths wrote: If one is feeling paranoid about ground loop noise (and wishes to avoid transformers, optoisolators , or fibre optics), etc one could always use an LVDS driver with a batter powered(?) LVDS to CMOS receiver/translator right at the 5370A/B input BNC connector. This may be useful for a DMTD system that uses a 5370A/B. Bruce Bob Camp wrote: Hi AC cmos will easily drive an L pad to match a 50 ohm cable at these levels. That's true at either 3.3 or at 5.0 volts. There are a lot of cmos families out there that beat AC for speed and match the output drive capability. Bob On Feb 27, 2010, at 9:12 PM, Bruce Griffiths wrote: 1) One method with 5V CMOS is to add a resistive voltage divider at the CMOS driver output with a 50 ohm output impedance at the tap that drives the 5370A/B input. 2) If one has a 5V 50 ohm driver (eg Thunderbolt PPS output) use a 50 ohm attenuator at the 5370A/B input. For a 5370A an attenuation of at least 11dB is required. For a 5370B an attenuation of at least 3dB is required. 3) One can always use the 10x input attenuation setting built in to the 5370A/B however this reduces the signal swing to 0.5V at the trigger amplifier input (5V CMOS input). 4) Attenuate the output of the logic signal by a factor of 2 and use an npn emitter follower to drive the 50 ohm load. 5) Use 3.3V CMOS signal levels for the 5370B. 6) Use a current mode emitter or source coupled switch to drive the 5370A/B input. The switching jitter of the above drivers will be much lower than the internal noise of the 5370A/B as long as HCMOS or faster logic is employed. Bruce Bob Camp wrote: Hi Which *still* carefully avoids the issue of how . Bob On Feb 27, 2010, at 8:52 PM, Bruce Griffiths wrote: Oops! a small correction (2nd paragraph): For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370B attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum. An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). Thus using the PPS output (~270 ohm is series with a 5V 74AC04 output) from a Synergy evaluation board that uses an M12M or M12+ GPS timing receiver to drive the inputs (with a 0-750mV signal) of a 5370A or 5370B is well within the recommended input signal range for high performance. This avoids having to adding an external 5V 50 ohm driver that some would use. Bruce Bob Camp wrote: Hi So exactly how did you know that I bought a (cheap) 5370B a few hours ago on the e-place and was just about to ask about how best to use it. H... Bob On Feb 27, 2010, at 7:01 PM, Bruce Griffiths wrote: The attached excerpts from the 5370A and 5370B manuals indicate that for best performance, that the common practice of driving the 5370A/B 1x inputs directly from a 5V CMOS logic signal is a bad idea. For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370A attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum. An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). Bruce 5370ATriggering.png5370BTriggering.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.
Re: [time-nuts] Achieving maximum performance when driving 5370A/B inputs
Hi I don't even have the counter and already we're butchering it The big issue is suitable twin-ax connectors and cable. I have both, but they are *big*. They never really made it into the world of miniature connectors and miniature cable. Shielded twisted pair would be another option. That eliminates the cable as an issue. Small connectors (BNC drop in) are still an issue though. Bob On Feb 27, 2010, at 9:48 PM, Bruce Griffiths wrote: Since the input amplifier and trigger circuit are located on a small daughter board it wouldn't be too difficult to replace this with an LVDS to CML stage. The only remaining isue would be what input connector to use (twinax??, SATA??). Bruce Bob Camp wrote: Hi Gee, LVDS what an unusual approach :) It would be nice if these instruments had a balanced input. Common mode noise is indeed an issue in a lot of cases. Of course wrapping the coax headed to the counter 10X around a fairly large core can help things a bit. Bob On Feb 27, 2010, at 9:32 PM, Bruce Griffiths wrote: If one is feeling paranoid about ground loop noise (and wishes to avoid transformers, optoisolators , or fibre optics), etc one could always use an LVDS driver with a batter powered(?) LVDS to CMOS receiver/translator right at the 5370A/B input BNC connector. This may be useful for a DMTD system that uses a 5370A/B. Bruce Bob Camp wrote: Hi AC cmos will easily drive an L pad to match a 50 ohm cable at these levels. That's true at either 3.3 or at 5.0 volts. There are a lot of cmos families out there that beat AC for speed and match the output drive capability. Bob On Feb 27, 2010, at 9:12 PM, Bruce Griffiths wrote: 1) One method with 5V CMOS is to add a resistive voltage divider at the CMOS driver output with a 50 ohm output impedance at the tap that drives the 5370A/B input. 2) If one has a 5V 50 ohm driver (eg Thunderbolt PPS output) use a 50 ohm attenuator at the 5370A/B input. For a 5370A an attenuation of at least 11dB is required. For a 5370B an attenuation of at least 3dB is required. 3) One can always use the 10x input attenuation setting built in to the 5370A/B however this reduces the signal swing to 0.5V at the trigger amplifier input (5V CMOS input). 4) Attenuate the output of the logic signal by a factor of 2 and use an npn emitter follower to drive the 50 ohm load. 5) Use 3.3V CMOS signal levels for the 5370B. 6) Use a current mode emitter or source coupled switch to drive the 5370A/B input. The switching jitter of the above drivers will be much lower than the internal noise of the 5370A/B as long as HCMOS or faster logic is employed. Bruce Bob Camp wrote: Hi Which *still* carefully avoids the issue of how . Bob On Feb 27, 2010, at 8:52 PM, Bruce Griffiths wrote: Oops! a small correction (2nd paragraph): For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370B attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum. An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). Thus using the PPS output (~270 ohm is series with a 5V 74AC04 output) from a Synergy evaluation board that uses an M12M or M12+ GPS timing receiver to drive the inputs (with a 0-750mV signal) of a 5370A or 5370B is well within the recommended input signal range for high performance. This avoids having to adding an external 5V 50 ohm driver that some would use. Bruce Bob Camp wrote: Hi So exactly how did you know that I bought a (cheap) 5370B a few hours ago on the e-place and was just about to ask about how best to use it. H... Bob On Feb 27, 2010, at 7:01 PM, Bruce Griffiths wrote: The attached excerpts from the 5370A and 5370B manuals indicate that for best performance, that the common practice of driving the 5370A/B 1x inputs directly from a 5V CMOS logic signal is a bad idea. For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370A attenuating the 5V CMOS
Re: [time-nuts] Achieving maximum performance when driving 5370A/B inputs
Mike Feher wrote: In general, what about the old National damn fast and super damn fast LH0032 LH0033? I used to use a lot of those in my designs many years ago. - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 The LH0032 was a fast FET input opamp. I presume you meant the LH0033 and LH0063? Their slew rate is adequate to ensure that the 5370A/B trigger jitter is insignificant. However they need a negative supply as well as the positive supply when being driven by a 3.3V or 5V CMOS output. Bruce ___ 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] Achieving maximum performance when driving 5370A/B inputs
Actually there are miniature twinax style connectors, for example: http://www.amphenolrf.com/products/twinbnc.asp?N=0sid=4B8860805409E17F; http://www.amphenolrf.com/products/twinbnc.asp?N=0sid=4B8860805409E17F; Bruce Bob Camp wrote: Hi I don't even have the counter and already we're butchering it The big issue is suitable twin-ax connectors and cable. I have both, but they are *big*. They never really made it into the world of miniature connectors and miniature cable. Shielded twisted pair would be another option. That eliminates the cable as an issue. Small connectors (BNC drop in) are still an issue though. Bob On Feb 27, 2010, at 9:48 PM, Bruce Griffiths wrote: Since the input amplifier and trigger circuit are located on a small daughter board it wouldn't be too difficult to replace this with an LVDS to CML stage. The only remaining isue would be what input connector to use (twinax??, SATA??). Bruce Bob Camp wrote: Hi Gee, LVDS what an unusual approach :) It would be nice if these instruments had a balanced input. Common mode noise is indeed an issue in a lot of cases. Of course wrapping the coax headed to the counter 10X around a fairly large core can help things a bit. Bob On Feb 27, 2010, at 9:32 PM, Bruce Griffiths wrote: If one is feeling paranoid about ground loop noise (and wishes to avoid transformers, optoisolators , or fibre optics), etc one could always use an LVDS driver with a batter powered(?) LVDS to CMOS receiver/translator right at the 5370A/B input BNC connector. This may be useful for a DMTD system that uses a 5370A/B. Bruce Bob Camp wrote: Hi AC cmos will easily drive an L pad to match a 50 ohm cable at these levels. That's true at either 3.3 or at 5.0 volts. There are a lot of cmos families out there that beat AC for speed and match the output drive capability. Bob On Feb 27, 2010, at 9:12 PM, Bruce Griffiths wrote: 1) One method with 5V CMOS is to add a resistive voltage divider at the CMOS driver output with a 50 ohm output impedance at the tap that drives the 5370A/B input. 2) If one has a 5V 50 ohm driver (eg Thunderbolt PPS output) use a 50 ohm attenuator at the 5370A/B input. For a 5370A an attenuation of at least 11dB is required. For a 5370B an attenuation of at least 3dB is required. 3) One can always use the 10x input attenuation setting built in to the 5370A/B however this reduces the signal swing to 0.5V at the trigger amplifier input (5V CMOS input). 4) Attenuate the output of the logic signal by a factor of 2 and use an npn emitter follower to drive the 50 ohm load. 5) Use 3.3V CMOS signal levels for the 5370B. 6) Use a current mode emitter or source coupled switch to drive the 5370A/B input. The switching jitter of the above drivers will be much lower than the internal noise of the 5370A/B as long as HCMOS or faster logic is employed. Bruce Bob Camp wrote: Hi Which *still* carefully avoids the issue of how . Bob On Feb 27, 2010, at 8:52 PM, Bruce Griffiths wrote: Oops! a small correction (2nd paragraph): For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370B attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum. An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). Thus using the PPS output (~270 ohm is series with a 5V 74AC04 output) from a Synergy evaluation board that uses an M12M or M12+ GPS timing receiver to drive the inputs (with a 0-750mV signal) of a 5370A or 5370B is well within the recommended input signal range for high performance. This avoids having to adding an external 5V 50 ohm driver that some would use. Bruce Bob Camp wrote: Hi So exactly how did you know that I bought a (cheap) 5370B a few hours ago on the e-place and was just about to ask about how best to use it. H... Bob On Feb 27, 2010, at 7:01 PM, Bruce Griffiths wrote: The attached excerpts from the 5370A and 5370B manuals indicate that for best performance, that the common practice of driving the 5370A/B 1x inputs directly from a 5V CMOS logic signal is a bad idea. For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal
Re: [time-nuts] Achieving maximum performance when driving 5370A/B inputs
Hi Sure never seen any of them on any gear in my junk pile. I also never seen a customer ask for them as an output connector on an oscillator. I wonder how common they actually are. Bob On Feb 27, 2010, at 9:59 PM, Bruce Griffiths wrote: Actually there are miniature twinax style connectors, for example: http://www.amphenolrf.com/products/twinbnc.asp?N=0sid=4B8860805409E17F; http://www.amphenolrf.com/products/twinbnc.asp?N=0sid=4B8860805409E17F; Bruce Bob Camp wrote: Hi I don't even have the counter and already we're butchering it The big issue is suitable twin-ax connectors and cable. I have both, but they are *big*. They never really made it into the world of miniature connectors and miniature cable. Shielded twisted pair would be another option. That eliminates the cable as an issue. Small connectors (BNC drop in) are still an issue though. Bob On Feb 27, 2010, at 9:48 PM, Bruce Griffiths wrote: Since the input amplifier and trigger circuit are located on a small daughter board it wouldn't be too difficult to replace this with an LVDS to CML stage. The only remaining isue would be what input connector to use (twinax??, SATA??). Bruce Bob Camp wrote: Hi Gee, LVDS what an unusual approach :) It would be nice if these instruments had a balanced input. Common mode noise is indeed an issue in a lot of cases. Of course wrapping the coax headed to the counter 10X around a fairly large core can help things a bit. Bob On Feb 27, 2010, at 9:32 PM, Bruce Griffiths wrote: If one is feeling paranoid about ground loop noise (and wishes to avoid transformers, optoisolators , or fibre optics), etc one could always use an LVDS driver with a batter powered(?) LVDS to CMOS receiver/translator right at the 5370A/B input BNC connector. This may be useful for a DMTD system that uses a 5370A/B. Bruce Bob Camp wrote: Hi AC cmos will easily drive an L pad to match a 50 ohm cable at these levels. That's true at either 3.3 or at 5.0 volts. There are a lot of cmos families out there that beat AC for speed and match the output drive capability. Bob On Feb 27, 2010, at 9:12 PM, Bruce Griffiths wrote: 1) One method with 5V CMOS is to add a resistive voltage divider at the CMOS driver output with a 50 ohm output impedance at the tap that drives the 5370A/B input. 2) If one has a 5V 50 ohm driver (eg Thunderbolt PPS output) use a 50 ohm attenuator at the 5370A/B input. For a 5370A an attenuation of at least 11dB is required. For a 5370B an attenuation of at least 3dB is required. 3) One can always use the 10x input attenuation setting built in to the 5370A/B however this reduces the signal swing to 0.5V at the trigger amplifier input (5V CMOS input). 4) Attenuate the output of the logic signal by a factor of 2 and use an npn emitter follower to drive the 50 ohm load. 5) Use 3.3V CMOS signal levels for the 5370B. 6) Use a current mode emitter or source coupled switch to drive the 5370A/B input. The switching jitter of the above drivers will be much lower than the internal noise of the 5370A/B as long as HCMOS or faster logic is employed. Bruce Bob Camp wrote: Hi Which *still* carefully avoids the issue of how . Bob On Feb 27, 2010, at 8:52 PM, Bruce Griffiths wrote: Oops! a small correction (2nd paragraph): For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370B attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum. An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). Thus using the PPS output (~270 ohm is series with a 5V 74AC04 output) from a Synergy evaluation board that uses an M12M or M12+ GPS timing receiver to drive the inputs (with a 0-750mV signal) of a 5370A or 5370B is well within the recommended input signal range for high performance. This avoids having to adding an external 5V 50 ohm driver that some would use. Bruce Bob Camp wrote: Hi So exactly how did you know that I bought a (cheap) 5370B a few hours ago on the e-place and was just about to ask about how best to use it. H... Bob On Feb 27, 2010, at 7:01 PM, Bruce Griffiths wrote: The attached excerpts from the 5370A and 5370B manuals
Re: [time-nuts] Achieving maximum performance when driving 5370A/B inputs
You could look at a surplus F16 (probably wont fit in your garage though) or similar STP was heavily used in MIL STD 1553 avionics buses. Bruce Bob Camp wrote: Hi Sure never seen any of them on any gear in my junk pile. I also never seen a customer ask for them as an output connector on an oscillator. I wonder how common they actually are. Bob On Feb 27, 2010, at 9:59 PM, Bruce Griffiths wrote: Actually there are miniature twinax style connectors, for example: http://www.amphenolrf.com/products/twinbnc.asp?N=0sid=4B8860805409E17F; http://www.amphenolrf.com/products/twinbnc.asp?N=0sid=4B8860805409E17F; Bruce Bob Camp wrote: Hi I don't even have the counter and already we're butchering it The big issue is suitable twin-ax connectors and cable. I have both, but they are *big*. They never really made it into the world of miniature connectors and miniature cable. Shielded twisted pair would be another option. That eliminates the cable as an issue. Small connectors (BNC drop in) are still an issue though. Bob On Feb 27, 2010, at 9:48 PM, Bruce Griffiths wrote: Since the input amplifier and trigger circuit are located on a small daughter board it wouldn't be too difficult to replace this with an LVDS to CML stage. The only remaining isue would be what input connector to use (twinax??, SATA??). Bruce Bob Camp wrote: Hi Gee, LVDS what an unusual approach :) It would be nice if these instruments had a balanced input. Common mode noise is indeed an issue in a lot of cases. Of course wrapping the coax headed to the counter 10X around a fairly large core can help things a bit. Bob On Feb 27, 2010, at 9:32 PM, Bruce Griffiths wrote: If one is feeling paranoid about ground loop noise (and wishes to avoid transformers, optoisolators , or fibre optics), etc one could always use an LVDS driver with a batter powered(?) LVDS to CMOS receiver/translator right at the 5370A/B input BNC connector. This may be useful for a DMTD system that uses a 5370A/B. Bruce Bob Camp wrote: Hi AC cmos will easily drive an L pad to match a 50 ohm cable at these levels. That's true at either 3.3 or at 5.0 volts. There are a lot of cmos families out there that beat AC for speed and match the output drive capability. Bob On Feb 27, 2010, at 9:12 PM, Bruce Griffiths wrote: 1) One method with 5V CMOS is to add a resistive voltage divider at the CMOS driver output with a 50 ohm output impedance at the tap that drives the 5370A/B input. 2) If one has a 5V 50 ohm driver (eg Thunderbolt PPS output) use a 50 ohm attenuator at the 5370A/B input. For a 5370A an attenuation of at least 11dB is required. For a 5370B an attenuation of at least 3dB is required. 3) One can always use the 10x input attenuation setting built in to the 5370A/B however this reduces the signal swing to 0.5V at the trigger amplifier input (5V CMOS input). 4) Attenuate the output of the logic signal by a factor of 2 and use an npn emitter follower to drive the 50 ohm load. 5) Use 3.3V CMOS signal levels for the 5370B. 6) Use a current mode emitter or source coupled switch to drive the 5370A/B input. The switching jitter of the above drivers will be much lower than the internal noise of the 5370A/B as long as HCMOS or faster logic is employed. Bruce Bob Camp wrote: Hi Which *still* carefully avoids the issue of how . Bob On Feb 27, 2010, at 8:52 PM, Bruce Griffiths wrote: Oops! a small correction (2nd paragraph): For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370B attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum. An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). Thus using the PPS output (~270 ohm is series with a 5V 74AC04 output) from a Synergy evaluation board that uses an M12M or M12+ GPS timing receiver to drive the inputs (with a 0-750mV signal) of a 5370A or 5370B is well within the recommended input signal range for high performance. This avoids having to adding an external 5V 50 ohm driver that some would use. Bruce Bob Camp wrote: Hi So exactly how did you know that I bought a (cheap) 5370B a few hours ago on the e-place and was just about to ask about how best to use it. H... Bob On Feb 27, 2010, at 7:01 PM, Bruce Griffiths wrote:
Re: [time-nuts] Achieving maximum performance when driving 5370A/B inputs
Hi MIght have to move a few things in the shed to fin in an F16. If they were used in quantity there aught to be cable and connectors out there. The only reason I have the stuff I do is good old IBM and their approach to networking back in the old days. It would be tough to properly drive an R-390 otherwise. Bob On Feb 27, 2010, at 10:10 PM, Bruce Griffiths wrote: You could look at a surplus F16 (probably wont fit in your garage though) or similar STP was heavily used in MIL STD 1553 avionics buses. Bruce Bob Camp wrote: Hi Sure never seen any of them on any gear in my junk pile. I also never seen a customer ask for them as an output connector on an oscillator. I wonder how common they actually are. Bob On Feb 27, 2010, at 9:59 PM, Bruce Griffiths wrote: Actually there are miniature twinax style connectors, for example: http://www.amphenolrf.com/products/twinbnc.asp?N=0sid=4B8860805409E17F; http://www.amphenolrf.com/products/twinbnc.asp?N=0sid=4B8860805409E17F; Bruce Bob Camp wrote: Hi I don't even have the counter and already we're butchering it The big issue is suitable twin-ax connectors and cable. I have both, but they are *big*. They never really made it into the world of miniature connectors and miniature cable. Shielded twisted pair would be another option. That eliminates the cable as an issue. Small connectors (BNC drop in) are still an issue though. Bob On Feb 27, 2010, at 9:48 PM, Bruce Griffiths wrote: Since the input amplifier and trigger circuit are located on a small daughter board it wouldn't be too difficult to replace this with an LVDS to CML stage. The only remaining isue would be what input connector to use (twinax??, SATA??). Bruce Bob Camp wrote: Hi Gee, LVDS what an unusual approach :) It would be nice if these instruments had a balanced input. Common mode noise is indeed an issue in a lot of cases. Of course wrapping the coax headed to the counter 10X around a fairly large core can help things a bit. Bob On Feb 27, 2010, at 9:32 PM, Bruce Griffiths wrote: If one is feeling paranoid about ground loop noise (and wishes to avoid transformers, optoisolators , or fibre optics), etc one could always use an LVDS driver with a batter powered(?) LVDS to CMOS receiver/translator right at the 5370A/B input BNC connector. This may be useful for a DMTD system that uses a 5370A/B. Bruce Bob Camp wrote: Hi AC cmos will easily drive an L pad to match a 50 ohm cable at these levels. That's true at either 3.3 or at 5.0 volts. There are a lot of cmos families out there that beat AC for speed and match the output drive capability. Bob On Feb 27, 2010, at 9:12 PM, Bruce Griffiths wrote: 1) One method with 5V CMOS is to add a resistive voltage divider at the CMOS driver output with a 50 ohm output impedance at the tap that drives the 5370A/B input. 2) If one has a 5V 50 ohm driver (eg Thunderbolt PPS output) use a 50 ohm attenuator at the 5370A/B input. For a 5370A an attenuation of at least 11dB is required. For a 5370B an attenuation of at least 3dB is required. 3) One can always use the 10x input attenuation setting built in to the 5370A/B however this reduces the signal swing to 0.5V at the trigger amplifier input (5V CMOS input). 4) Attenuate the output of the logic signal by a factor of 2 and use an npn emitter follower to drive the 50 ohm load. 5) Use 3.3V CMOS signal levels for the 5370B. 6) Use a current mode emitter or source coupled switch to drive the 5370A/B input. The switching jitter of the above drivers will be much lower than the internal noise of the 5370A/B as long as HCMOS or faster logic is employed. Bruce Bob Camp wrote: Hi Which *still* carefully avoids the issue of how . Bob On Feb 27, 2010, at 8:52 PM, Bruce Griffiths wrote: Oops! a small correction (2nd paragraph): For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370B attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum. An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). Thus using the PPS output (~270 ohm is series with a 5V 74AC04 output) from a Synergy evaluation board that uses an M12M or M12+ GPS
Re: [time-nuts] Achieving maximum performance when driving 5370A/Binputs
Bob Camp li...@rtty.us wrote: Hi MIght have to move a few things in the shed to fin in an F16. If they were used in quantity there aught to be cable and connectors out there. The only reason I have the stuff I do is good old IBM and their approach to networking back in the old days. It would be tough to properly drive an R-390 otherwise. R-390 or S/390? :-) -ls- ___ 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] Achieving maximum performance when driving 5370A/Binputs
Hi R-390 and / or R-390A Not a lot of IBM stuff here. I can fit in a F-16 only because I've avoided the IBM stuff Bob On Feb 27, 2010, at 10:18 PM, Larry Snyder wrote: Bob Camp li...@rtty.us wrote: Hi MIght have to move a few things in the shed to fin in an F16. If they were used in quantity there aught to be cable and connectors out there. The only reason I have the stuff I do is good old IBM and their approach to networking back in the old days. It would be tough to properly drive an R-390 otherwise. R-390 or S/390? :-) -ls- ___ 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] Achieving maximum performance when driving 5370A/B inputs
R-390 or S/390? The R-390 receiver (designed by Collins) is probably worth more today than an S390. ;-) ___ 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] Achieving maximum performance when driving 5370A/B inputs
here is a two center pin type of BNC, presumably for a balanced twisted pair or twin ax type cable. The shape of the dielectric allows proper mechanical mating. Stan, W1LE Cape Cod Bob Camp wrote: Hi I don't even have the counter and already we're butchering it The big issue is suitable twin-ax connectors and cable. I have both, but they are *big*. They never really made it into the world of miniature connectors and miniature cable. Shielded twisted pair would be another option. That eliminates the cable as an issue. Small connectors (BNC drop in) are still an issue though. ___ 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] Looking for a 5370 red digit cover/window
I need the red plastic digit cover/window [approximately 1 3/4 x 14 3/4] to complete the repair of a HP 5370 counter/timer. I don't care if it says 5370A or B. I assume that no major change occurred other than the unit identifier changing. Perhaps someone can correct me if I am wrong in making this assumption. It would be nice to get the bezel clip/strip too, however I suspect that they tend to disintegrate during removal of the red display cover. Does anyone have this available from a parts chassis in their lab? I would be happy to pay a reasonable price plus postage. I am located in Kalamazoo, Michigan, USA. Jim Cotton n8qoh ___ 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] Achieving maximum performance when driving 5370A/B inputs
I have a bnc type connector with two pins inside the shield on a FTS cesium standard labeled DS1 must be a phone industry jack. Stanley - Original Message From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sat, February 27, 2010 8:53:16 PM Subject: Re: [time-nuts] Achieving maximum performance when driving 5370A/B inputs Hi I don't even have the counter and already we're butchering it The big issue is suitable twin-ax connectors and cable. I have both, but they are *big*. They never really made it into the world of miniature connectors and miniature cable. Shielded twisted pair would be another option. That eliminates the cable as an issue. Small connectors (BNC drop in) are still an issue though. Bob On Feb 27, 2010, at 9:48 PM, Bruce Griffiths wrote: Since the input amplifier and trigger circuit are located on a small daughter board it wouldn't be too difficult to replace this with an LVDS to CML stage. The only remaining isue would be what input connector to use (twinax??, SATA??). Bruce Bob Camp wrote: Hi Gee, LVDS what an unusual approach :) It would be nice if these instruments had a balanced input. Common mode noise is indeed an issue in a lot of cases. Of course wrapping the coax headed to the counter 10X around a fairly large core can help things a bit. Bob On Feb 27, 2010, at 9:32 PM, Bruce Griffiths wrote: If one is feeling paranoid about ground loop noise (and wishes to avoid transformers, optoisolators , or fibre optics), etc one could always use an LVDS driver with a batter powered(?) LVDS to CMOS receiver/translator right at the 5370A/B input BNC connector. This may be useful for a DMTD system that uses a 5370A/B. Bruce Bob Camp wrote: Hi AC cmos will easily drive an L pad to match a 50 ohm cable at these levels. That's true at either 3.3 or at 5.0 volts. There are a lot of cmos families out there that beat AC for speed and match the output drive capability. Bob On Feb 27, 2010, at 9:12 PM, Bruce Griffiths wrote: 1) One method with 5V CMOS is to add a resistive voltage divider at the CMOS driver output with a 50 ohm output impedance at the tap that drives the 5370A/B input. 2) If one has a 5V 50 ohm driver (eg Thunderbolt PPS output) use a 50 ohm attenuator at the 5370A/B input. For a 5370A an attenuation of at least 11dB is required. For a 5370B an attenuation of at least 3dB is required. 3) One can always use the 10x input attenuation setting built in to the 5370A/B however this reduces the signal swing to 0.5V at the trigger amplifier input (5V CMOS input). 4) Attenuate the output of the logic signal by a factor of 2 and use an npn emitter follower to drive the 50 ohm load. 5) Use 3.3V CMOS signal levels for the 5370B. 6) Use a current mode emitter or source coupled switch to drive the 5370A/B input. The switching jitter of the above drivers will be much lower than the internal noise of the 5370A/B as long as HCMOS or faster logic is employed. Bruce Bob Camp wrote: Hi Which *still* carefully avoids the issue of how . Bob On Feb 27, 2010, at 8:52 PM, Bruce Griffiths wrote: Oops! a small correction (2nd paragraph): For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370B attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum. An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). Thus using the PPS output (~270 ohm is series with a 5V 74AC04 output) from a Synergy evaluation board that uses an M12M or M12+ GPS timing receiver to drive the inputs (with a 0-750mV signal) of a 5370A or 5370B is well within the recommended input signal range for high performance. This avoids having to adding an external 5V 50 ohm driver that some would use. Bruce Bob Camp wrote: Hi So exactly how did you know that I bought a (cheap) 5370B a few hours ago on the e-place and was just about to ask about how best to use it. H... Bob On Feb 27, 2010, at 7:01 PM, Bruce Griffiths wrote: The attached excerpts from the 5370A and 5370B manuals indicate that for best performance, that the common practice of driving the 5370A/B 1x inputs directly from a 5V CMOS logic signal is a bad idea. For the 5370A
Re: [time-nuts] Achieving maximum performance when driving 5370A/Binputs
Arthur Dent golgarfrinc...@yahoo.com wrote: R-390 or S/390? The R-390 receiver (designed by Collins) is probably worth more today than an S390. ;-) Good point, and I apologize for the smart remark. I've worked with both (and a Z900 Cu box is pretty quick :-) -ls- ___ 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] Achieving maximum performance when driving 5370A/B inputs
Mike Feher wrote: In general, what about the old National damn fast and super damn fast LH0032 LH0033? I used to use a lot of those in my designs many years ago. - Mike Gotta really decouple the power supplies on those puppies... ___ 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] Achieving maximum performance when driving 5370A/B inputs
Bob Camp wrote: Hi Sure never seen any of them on any gear in my junk pile. I also never seen a customer ask for them as an output connector on an oscillator. I wonder how common they actually are. Bob On Feb 27, 2010, at 9:59 PM, Bruce Griffiths wrote: Actually there are miniature twinax style connectors, for example: http://www.amphenolrf.com/products/twinbnc.asp?N=0sid=4B8860805409E17F; http://www.amphenolrf.com/products/twinbnc.asp?N=0sid=4B8860805409E17F; Bruce Bob Camp wrote: There's a variety of these kind of things. You see them in MIL-STD-1553B systems, among others. Triax is also fairly common as a connector for shielded twisted pair. There are also twisted pair inserts for the DB-25 sized shell (actually a quad pair with 4 inserts). The one that has one pin and one socket on each side is a much better strategy than the one that has 2 pins on one connector and 2 sockets on the other. ___ 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] Achieving maximum performance when driving 5370A/B inputs
These were used on some measuring instruments to provide a balance 'guarded' input. The shield around the balanced conductors provided a ground between the DUT and the measuring equipment that was not connected to the input. IIRC this was for very low level signals. 73 Glenn WB4UIV At 10:06 PM 2/27/2010, you wrote: Hi Sure never seen any of them on any gear in my junk pile. I also never seen a customer ask for them as an output connector on an oscillator. I wonder how common they actually are. Bob On Feb 27, 2010, at 9:59 PM, Bruce Griffiths wrote: Actually there are miniature twinax style connectors, for example: http://www.amphenolrf.com/products/twinbnc.asp?N=0sid=4B8860805409E17F; http://www.amphenolrf.com/products/twinbnc.asp?N=0sid=4B8860805409E17F; Bruce Bob Camp wrote: Hi I don't even have the counter and already we're butchering it The big issue is suitable twin-ax connectors and cable. I have both, but they are *big*. They never really made it into the world of miniature connectors and miniature cable. Shielded twisted pair would be another option. That eliminates the cable as an issue. Small connectors (BNC drop in) are still an issue though. Bob On Feb 27, 2010, at 9:48 PM, Bruce Griffiths wrote: Since the input amplifier and trigger circuit are located on a small daughter board it wouldn't be too difficult to replace this with an LVDS to CML stage. The only remaining isue would be what input connector to use (twinax??, SATA??). Bruce Bob Camp wrote: Hi Gee, LVDS what an unusual approach :) It would be nice if these instruments had a balanced input. Common mode noise is indeed an issue in a lot of cases. Of course wrapping the coax headed to the counter 10X around a fairly large core can help things a bit. Bob On Feb 27, 2010, at 9:32 PM, Bruce Griffiths wrote: If one is feeling paranoid about ground loop noise (and wishes to avoid transformers, optoisolators , or fibre optics), etc one could always use an LVDS driver with a batter powered(?) LVDS to CMOS receiver/translator right at the 5370A/B input BNC connector. This may be useful for a DMTD system that uses a 5370A/B. Bruce Bob Camp wrote: Hi AC cmos will easily drive an L pad to match a 50 ohm cable at these levels. That's true at either 3.3 or at 5.0 volts. There are a lot of cmos families out there that beat AC for speed and match the output drive capability. Bob On Feb 27, 2010, at 9:12 PM, Bruce Griffiths wrote: 1) One method with 5V CMOS is to add a resistive voltage divider at the CMOS driver output with a 50 ohm output impedance at the tap that drives the 5370A/B input. 2) If one has a 5V 50 ohm driver (eg Thunderbolt PPS output) use a 50 ohm attenuator at the 5370A/B input. For a 5370A an attenuation of at least 11dB is required. For a 5370B an attenuation of at least 3dB is required. 3) One can always use the 10x input attenuation setting built in to the 5370A/B however this reduces the signal swing to 0.5V at the trigger amplifier input (5V CMOS input). 4) Attenuate the output of the logic signal by a factor of 2 and use an npn emitter follower to drive the 50 ohm load. 5) Use 3.3V CMOS signal levels for the 5370B. 6) Use a current mode emitter or source coupled switch to drive the 5370A/B input. The switching jitter of the above drivers will be much lower than the internal noise of the 5370A/B as long as HCMOS or faster logic is employed. Bruce Bob Camp wrote: Hi Which *still* carefully avoids the issue of how . Bob On Feb 27, 2010, at 8:52 PM, Bruce Griffiths wrote: Oops! a small correction (2nd paragraph): For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370B attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum. An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). Thus using the PPS output (~270 ohm is series with a 5V 74AC04 output) from a Synergy evaluation board that uses an M12M or M12+ GPS timing receiver to drive the inputs (with a 0-750mV signal) of a 5370A or 5370B is well within the recommended input signal range for high performance. This avoids having to adding an external 5V 50 ohm driver that some would use. Bruce Bob Camp wrote: Hi So exactly how did you know that I bought a (cheap) 5370B a few hours ago on the e-place and was just about to ask about how best to use
Re: [time-nuts] Achieving maximum performance when driving 5370A/B inputs
found a picture of the Twin BNC here: http://drawings.amphenolrf.com/pdf/172.pdf ___ 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] Achieving maximum performance when driving 5370A/B inputs
If it's the one that I think it is... look closely at the photo. The shafts on two of the pots are sheared off at the panel. These are the display update control and the external arming level control. These were custom HP pots with a funky (and delicate) switch. They had brittle plastic shafts.Gee, how do I know this... could it be that a large percentage of the 5370's for sale have the same defect? Luckily those controls are not too critical for normal operation. They can be replaced with regular (switchless) pots if you jumper the switch pads correctly. Be careful, there were two different layouts to those controls. -- So exactly how did you know that I bought a (cheap) 5370B a few hours ago on the e-place _ Hotmail: Trusted email with powerful SPAM protection. http://clk.atdmt.com/GBL/go/201469227/direct/01/ ___ 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] DMTD Mixer Terminations
The values in the schematics are wrong for the op amp gain. The drawing was from an earlier drawing where I made a preamp to start checks on the mixers, and I sent it to you (Bruce G). Thats when you determined I did not have enough gain to get near the noise floor. The THAT1512/1646 ICs were ordered to make a new preamp for the future measurements on the mixers. When I use the scope and check the outputs of the IC, I have 20 volts peak to peak, sine-wave. I know from previous readings I see about 500 mv p-p out of the mixer. I went down to the bench and the resistors I used were still there (I bought several taped reels of Dale RN55D resistors when a local business went out). I used 294 ohms and 14.9 kilo-ohms, for a gain of 50 (the power rails are +/- 15 volts). Also not shown on the schematic is a 0.47 uF cap around the 14.9 kilo-ohm resistor. I think I was trying to limit the bandwidth to around 15 hertz. Also the resistor going between the op amp and the limiting diodes was marked 10K, its 20K. The diodes are 1N4148. Corrected drawing attached. This is what happens to time nuts who can only play on the weekend and stay up all nightand my employer just thinks I party too hard.for Monday mornings. Brian KD4FM Bruce Griffiths wrote: The LT1037 is shown with a gain of ~1690x, if this amplifier is used to amplify the beat frequency signal, it will saturate. Opamp recovery from saturation is poorly documented and may be very slow. It would be better to use some diodes in the amplifier feedback network to limit the large signal gain to 5x (so that the LT1037 remains stable as it isn't unity gain stable). This will ensure a somewhat faster recovery from overload as the LT1037 then avoids saturation and the opamp input stage remains in the linear region. Bruce Bob Camp wrote: Hi Assuming that the junction of the back to back diodes goes trough a chunk of coax to get to the counter: You are forming a low pass filter with the 10K resistor and the coax capacitance. The LT1037 is quite happy driving a 600 ohm load. You could easily drop the impedance at that point below 300 ohms. That should give you a faster edge into the counter. You also should check the slew rate performance of the 1037. You don't want the op amp to be slew rate limited. Bob On Feb 27, 2010, at 12:41 PM, Brian Kirby wrote: I am in the process of designing a DMTD system. As an experiment to do basic measurements on the chosen mixer, I used a capacitor (0.01 uF) in series to ground with a 47 ohm metal film resistor. Where the capacitor and resistor meets, another resistor is attached (390 ohms) that goes to ground. The idea is to provide a 50 ohm termination at 20 Mhz and a lighter termination at audio frequencies. I seen this is a NBS note and I can say, its a starting point for my experiments. This (my) system is designed for 10 Mhz, using a 10 hertz beat. A schematic is attached of what I am experimenting with at the moment. A HP5370B is the recording instrument. The noise floor from 1 days observations show 2x10-11 at 0.1 seconds, 2x10-12 at 1 sec, 5x10-13 at 10 sec, 6x10-14 at 100 sec, 7x10-15 at 1000 sec, and 7x10-16 at 10,000 secs. It will be interesting when the project is completed to see how much improvement there will be. As I understand (or learning..) mixer performance is the key to the DMTD system. It occurs to me that maybe a capacitor designed for 50 ohms at 20 mhz may be a better termination (for the IF port) for this mixer. A 16 pF capacitor is 50 ohms at 20 mhz, and for comparison at 10 hertz, it would be 100 meg-ohms, which would give maximum amplitude at 10 hertz. As I understand, a capacitor terminated mixer will give a triangle wave output, which is very beneficial to the design - as the end result is to get maximum slope out of the mixer. I would say, unqualified as I am, the capacitor termination matches the 20 mhz signal, and helps attenuates the harmonics of the mixer, and has no , or very little effect on the audio frequencies that we are interested in. And saying/rambling on... that if maximum slope is needed, its needed on the 10 hertz beat signal - so maybe a capacitive termination on the 10 hertz signal only and something resistive on the 20 mhz signalanother idea use the 16 pF direct off the mixer, then a series resistor for isolation and then a large capacitor on the 10 hertz beat for maximum slope. At the present, I am awaiting parts to build a low noise preamp base on the THAT1512 so I can make better measurements on the mixer. Bruce has provided a lot of good suggestions and helpful comments on my project and Ulrich has provided me quite a bit of user support on his program, Plotter. Thanks to all. Comments ? Brian KD4FM DMTD_Plans.pdf___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
[time-nuts] Digests too often...
Hi the gang, Why the Digest of this group is sent evey one or two hours? The digest objective is to receive not too often in one message a bunch of them, very usefull when you forward your emails to your mobile phone, here with this group I receive very often a digest with only few messages, this is very enoying on mobile phones. Many other groups are sending digests only one or maximum twice per day. All the bests. pf, F5BQP ___ 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] Digests too often...
Quoth Pierre-François (f5bqp_pfm) at 2010-02-28 16:55... Why the Digest of this group is sent evey one or two hours? Most mailing list softwares send either at a set interval OR when a certain number of messages are received - whichever happens first. This prevents a very busy system from sending out digests that may contain hundreds of messages. (Far too difficult to read through.) -- Matthew Smith Smiffytech - Technology Consulting Web Application Development Business: http://www.smiffytech.com/ Blog/personal: http://www.smiffysplace.com/ LinkedIn: http://www.linkedin.com/in/smiffy Skype: msmiffy Twitter: @smiffy ___ 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] Digests too often...
Most mailing list softwares send either at a set interval OR when a certain number of messages are received - whichever happens first. Or when the digest gets bigger than N bytes. -- These are my opinions, not necessarily my employer's. 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] Achieving maximum performance when driving 5370A/B inputs
Is that buttermilk or blueberry batter? :-) Don - Original Message - From: Bruce Griffiths bruce.griffi...@xtra.co.nz To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, February 27, 2010 7:32 PM Subject: Re: [time-nuts] Achieving maximum performance when driving 5370A/B inputs If one is feeling paranoid about ground loop noise (and wishes to avoid transformers, optoisolators , or fibre optics), etc one could always use an LVDS driver with a batter powered(?) LVDS to CMOS receiver/translator right at the 5370A/B input BNC connector. This may be useful for a DMTD system that uses a 5370A/B. Bruce Bob Camp wrote: Hi AC cmos will easily drive an L pad to match a 50 ohm cable at these levels. That's true at either 3.3 or at 5.0 volts. There are a lot of cmos families out there that beat AC for speed and match the output drive capability. Bob On Feb 27, 2010, at 9:12 PM, Bruce Griffiths wrote: 1) One method with 5V CMOS is to add a resistive voltage divider at the CMOS driver output with a 50 ohm output impedance at the tap that drives the 5370A/B input. 2) If one has a 5V 50 ohm driver (eg Thunderbolt PPS output) use a 50 ohm attenuator at the 5370A/B input. For a 5370A an attenuation of at least 11dB is required. For a 5370B an attenuation of at least 3dB is required. 3) One can always use the 10x input attenuation setting built in to the 5370A/B however this reduces the signal swing to 0.5V at the trigger amplifier input (5V CMOS input). 4) Attenuate the output of the logic signal by a factor of 2 and use an npn emitter follower to drive the 50 ohm load. 5) Use 3.3V CMOS signal levels for the 5370B. 6) Use a current mode emitter or source coupled switch to drive the 5370A/B input. The switching jitter of the above drivers will be much lower than the internal noise of the 5370A/B as long as HCMOS or faster logic is employed. Bruce Bob Camp wrote: Hi Which *still* carefully avoids the issue of how . Bob On Feb 27, 2010, at 8:52 PM, Bruce Griffiths wrote: Oops! a small correction (2nd paragraph): For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370B attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum. An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). Thus using the PPS output (~270 ohm is series with a 5V 74AC04 output) from a Synergy evaluation board that uses an M12M or M12+ GPS timing receiver to drive the inputs (with a 0-750mV signal) of a 5370A or 5370B is well within the recommended input signal range for high performance. This avoids having to adding an external 5V 50 ohm driver that some would use. Bruce Bob Camp wrote: Hi So exactly how did you know that I bought a (cheap) 5370B a few hours ago on the e-place and was just about to ask about how best to use it. H... Bob On Feb 27, 2010, at 7:01 PM, Bruce Griffiths wrote: The attached excerpts from the 5370A and 5370B manuals indicate that for best performance, that the common practice of driving the 5370A/B 1x inputs directly from a 5V CMOS logic signal is a bad idea. For the 5370A attenuating the 5V CMOS signal to a 1V swing with the threshold set to 0.5V is close to optimum. An input signal with limits of 0V and +1.4V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). For the 5370A attenuating the 5V CMOS signal to a 2V swing with the threshold set to 1V is close to optimum. An input signal with limits of 0V and +3.5V with a trigger threshold of 0.7V is the maximum usable (for high performance). An input signal with limits of 0V and +0.3V with a trigger threshold of 0.15V is the minimum usable (for high performance). Bruce 5370ATriggering.png5370BTriggering.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,
Re: [time-nuts] Achieving maximum performance when driving 5370A/Binputs
I've fixed shafts like this carefully with plastic swizzle sticks and super glue. Did I say carefully? a little dab'll do ya... Don - Original Message - From: Mark Sims hol...@hotmail.com To: time-nuts@febo.com Sent: Saturday, February 27, 2010 10:10 PM Subject: [time-nuts] Achieving maximum performance when driving 5370A/Binputs If it's the one that I think it is... look closely at the photo. The shafts on two of the pots are sheared off at the panel. These are the display update control and the external arming level control. These were custom HP pots with a funky (and delicate) switch. They had brittle plastic shafts.Gee, how do I know this... could it be that a large percentage of the 5370's for sale have the same defect? Luckily those controls are not too critical for normal operation. They can be replaced with regular (switchless) pots if you jumper the switch pads correctly. Be careful, there were two different layouts to those controls. -- So exactly how did you know that I bought a (cheap) 5370B a few hours ago on the e-place _ Hotmail: Trusted email with powerful SPAM protection. http://clk.atdmt.com/GBL/go/201469227/direct/01/ ___ 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.
