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] 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
[time-nuts] thunderbolt fault
Hi all, A friend just received a thunderbolt from an ebay seller today and asked me to check it and wire a quick power supply for him. I used a switching power supply, pc-like, just for testing and tried both lady heather and tboltmon. I wired the power lines as the TVB web page, but connected only one GND line as the connector supplied didn't have enough wires. The unit completes the self-survey and has all outputs (10 MHz and PPS), however, the temperature starts at -0 C at power on and in a few seconds settles to -1.249 C and never moves again. Also eeprom contents is invalid at each power on and no setting appears to survive after power off (not even the saved position). Does anyone know if there's a simple explanation for this or a possible common fault for eeprom and temperature or both eeprom and termometer chip are probably bad? I suggested the friend to ask for a refund anyway as my own thunderbolt works fine with default settings. Regards Francesco IZ8DWF ___ 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
Hello Francesco, After connecting to a known good power supply, active antenna, and computer, give it a chance to warm up and stabilize. After warm up, I get: +5VDC @ 0.250 A +12VDC @ 0.12 A -9VDC @ very low current, just barely moving the meter... consider a hard (factory) reset. set the menu to save the position and resurvey. If you can not get satisfaction, need to replace. With vendor approval, open it up, inspect, and clean out any debris. snug up all hardware, reassemble and retest.. Some vendors would prefer to get the defective unit back unopened. Stan, W1LE Cape Cod francesco messineo wrote: Hi all, A friend just received a thunderbolt from an ebay seller today and asked me to check it and wire a quick power supply for him. I used a switching power supply, pc-like, just for testing and tried both lady heather and tboltmon. I wired the power lines as the TVB web page, but connected only one GND line as the connector supplied didn't have enough wires. The unit completes the self-survey and has all outputs (10 MHz and PPS), however, the temperature starts at -0 C at power on and in a few seconds settles to -1.249 C and never moves again. Also eeprom contents is invalid at each power on and no setting appears to survive after power off (not even the saved position). Does anyone know if there's a simple explanation for this or a possible common fault for eeprom and temperature or both eeprom and termometer chip are probably bad? I suggested the friend to ask for a refund anyway as my own thunderbolt works fine with default settings. Regards Francesco IZ8DWF ___ 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
Hi Stan, On 2/26/10, Stan, W1LE stanw...@verizon.net wrote: Hello Francesco, After connecting to a known good power supply, active antenna, and computer, give it a chance to warm up and stabilize. After warm up, I get: +5VDC @ 0.250 A +12VDC @ 0.12 A -9VDC @ very low current, just barely moving the meter... it's actually +5V,+12 and -12V. Are there different versions? Mine works fine with these voltages, seen the requirement on the manual. However it completed the self survey two times and I set the save position flag. As I said I have one unit working fine, so I know what to expect from it. Each time the power goes off, it is reset to all defaults and eeprom is reported corrupted. I'll try an hard reset however. Thanks Francesco IZ8DWF ___ 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
The -12 can be anything from -7 to -12V and it will work. The units that were removed from Grayson or Andrew equipment had a zener diode changed on the Thunderbolt (by Trimble) that kept the power alarm from being invoked at low values of this voltage. 73, geo - n4ua On Fri, Feb 26, 2010 at 4:47 PM, francesco messineo francesco.messi...@gmail.com wrote: Hi Stan, On 2/26/10, Stan, W1LE stanw...@verizon.net wrote: Hello Francesco, After connecting to a known good power supply, active antenna, and computer, give it a chance to warm up and stabilize. After warm up, I get: +5VDC @ 0.250 A +12VDC @ 0.12 A -9VDC @ very low current, just barely moving the meter... it's actually +5V,+12 and -12V. Are there different versions? Mine works fine with these voltages, seen the requirement on the manual. However it completed the self survey two times and I set the save position flag. As I said I have one unit working fine, so I know what to expect from it. Each time the power goes off, it is reset to all defaults and eeprom is reported corrupted. I'll try an hard reset however. Thanks Francesco IZ8DWF ___ 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
Hi Has anybody actually measured the supply sensitivity on the -12 volt line to see weather a 5 volt change makes any noticeable difference in the output frequency? The power on -12 is very low, so there should be negligible thermal impact from a change. Bob On Feb 26, 2010, at 4:52 PM, George Dubovsky wrote: The -12 can be anything from -7 to -12V and it will work. The units that were removed from Grayson or Andrew equipment had a zener diode changed on the Thunderbolt (by Trimble) that kept the power alarm from being invoked at low values of this voltage. 73, geo - n4ua On Fri, Feb 26, 2010 at 4:47 PM, francesco messineo francesco.messi...@gmail.com wrote: Hi Stan, On 2/26/10, Stan, W1LE stanw...@verizon.net wrote: Hello Francesco, After connecting to a known good power supply, active antenna, and computer, give it a chance to warm up and stabilize. After warm up, I get: +5VDC @ 0.250 A +12VDC @ 0.12 A -9VDC @ very low current, just barely moving the meter... it's actually +5V,+12 and -12V. Are there different versions? Mine works fine with these voltages, seen the requirement on the manual. However it completed the self survey two times and I set the save position flag. As I said I have one unit working fine, so I know what to expect from it. Each time the power goes off, it is reset to all defaults and eeprom is reported corrupted. I'll try an hard reset however. Thanks Francesco IZ8DWF ___ 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] thunderbolt fault
Yes, I Did that, The +5 and -12 has NO effect on freq or operation of the unit except for really far out voltages. I tested mine with the -12 from -2 to -15 and could see no effect in the e-11 range. The -12 is used for the RS232 and the -Dac out so If you don't need the neg Dac out voltage or neg RS232 Drive, then it can pretty much be anything. But It should be kept in -7 to -13 range, and common sense means there should be little noise on it so it does not couple into other things. BUT the circuit it's self does not care what the supply is at or what is used. The +12 on the other hand, Needs to be stable and quiet with no ripple. I found using a +15 volt supply feeding a 12V three terminal will heat slinked regulator a good way to go to keep ALL the ripple out of the +12V ws *** Hi Has anybody actually measured the supply sensitivity on the -12 volt line to see weather a 5 volt change makes any noticeable difference in the output frequency? The power on -12 is very low, so there should be negligible thermal impact from a change. Bob On Feb 26, 2010, at 4:52 PM, George Dubovsky wrote: The -12 can be anything from -7 to -12V and it will work. The units that were removed from Grayson or Andrew equipment had a zener diode changed on the Thunderbolt (by Trimble) that kept the power alarm from being invoked at low values of this voltage. 73, geo - n4ua ___ 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 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 for the DAC or does that come off the +12? Is +5 just a digital supply? Lots of questions Bob On Feb 26, 2010, at 6:59 PM, WarrenS wrote: Yes, I Did that, The +5 and -12 has NO effect on freq or operation of the unit except for really far out voltages. I tested mine with the -12 from -2 to -15 and could see no effect in the e-11 range. The -12 is used for the RS232 and the -Dac out so If you don't need the neg Dac out voltage or neg RS232 Drive, then it can pretty much be anything. But It should be kept in -7 to -13 range, and common sense means there should be little noise on it so it does not couple into other things. BUT the circuit it's self does not care what the supply is at or what is used. The +12 on the other hand, Needs to be stable and quiet with no ripple. I found using a +15 volt supply feeding a 12V three terminal will heat slinked regulator a good way to go to keep ALL the ripple out of the +12V ws *** Hi Has anybody actually measured the supply sensitivity on the -12 volt line to see weather a 5 volt change makes any noticeable difference in the output frequency? The power on -12 is very low, so there should be negligible thermal impact from a change. Bob On Feb 26, 2010, at 4:52 PM, George Dubovsky wrote: The -12 can be anything from -7 to -12V and it will work. The units that were removed from Grayson or Andrew equipment had a zener diode changed on the Thunderbolt (by Trimble) that kept the power alarm from being invoked at low values of this voltage. 73, geo - n4ua ___ 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
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 for the DAC or does that come off the +12? Is +5 just a digital supply? Lots of questions Bob On Feb 26, 2010, at 6:59 PM, WarrenS wrote: Yes, I Did that, The +5 and -12 has NO effect on freq or operation of the unit except for really far out voltages. I tested mine with the -12 from -2 to -15 and could see no effect in the e-11 range. The -12 is used for the RS232 and the -Dac out so If you don't need the neg Dac out voltage or neg RS232 Drive, then it can pretty much be anything. But It should be kept in -7 to -13 range, and common sense means there should be little noise on it so it does not couple into other things. BUT the circuit it's self does not care what the supply is at or what is used. The +12 on the other hand, Needs to be stable and quiet with no ripple. I found using a +15 volt supply feeding a 12V three terminal will heat slinked regulator a good way to go to keep ALL the ripple out of the +12V ws *** Hi Has anybody actually measured the supply sensitivity on the -12 volt line to see weather a 5 volt change makes any noticeable difference in the output frequency? The power on -12 is very low, so there should be negligible thermal impact from a change. Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] thunderbolt fault
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 for the DAC or does that come off the +12? Is +5 just a digital supply? Lots of questions Bob On Feb 26, 2010, at 6:59 PM, WarrenS wrote: Yes, I Did that, The +5 and -12 has NO effect on freq or operation of the unit except for really far out voltages. I tested mine with the -12 from -2 to -15 and could see no effect in the e-11 range. The -12 is used for the RS232 and the -Dac out so If you don't need the neg Dac out voltage or neg RS232 Drive, then it can pretty much be anything. But It should be kept in -7 to -13 range, and common sense means there should be little noise on it so it does not couple into other things. BUT the circuit it's self does not care what the supply is at or what is used. The +12 on the other hand, Needs to be stable and quiet with no ripple. I found using a +15 volt supply feeding a 12V three terminal will heat slinked regulator a good way to go to keep ALL the ripple out of the +12V ws *** Hi Has anybody actually measured the supply sensitivity on the -12 volt line to see weather a 5 volt change makes any noticeable difference in the output frequency? The power on -12 is very low, so there should be negligible thermal impact from a change. Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] thunderbolt fault
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 for the DAC or does that come off the +12? Is +5 just a digital supply? Lots of questions Bob On Feb 26, 2010, at 6:59 PM, WarrenS wrote: Yes, I Did that, The +5 and -12 has NO effect on freq or operation of the unit except for really far out voltages. I tested mine with the -12 from -2 to -15 and could see no effect in the e-11 range. The -12 is used for the RS232 and the -Dac out so If you don't need the neg Dac out voltage or neg RS232 Drive, then it can pretty much be anything. But It should be kept in -7 to -13 range, and common sense means there should be little noise on it so it does not couple into other things. BUT the circuit it's self does not care what the supply is at or what is used. The +12 on the other hand, Needs to be stable and quiet with no ripple. I found using a +15 volt supply feeding a 12V three terminal will heat slinked regulator a good way to go to keep ALL the ripple out of the +12V ws *** Hi Has anybody actually measured the supply sensitivity on the -12 volt line to see weather a 5 volt change makes any noticeable difference in the output frequency? The power on -12 is very low, so there should be negligible thermal impact from a change. Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] thunderbolt fault
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 for the DAC or does that come off the +12? Is +5 just a digital supply? Lots of questions Bob On Feb 26, 2010, at 6:59 PM, WarrenS wrote: Yes, I Did that, The +5 and -12 has NO effect on freq or operation of the unit except for really far out voltages. I tested mine with the -12 from -2 to -15 and could see no effect in the e-11 range. The -12 is used for the RS232 and the -Dac out so If you don't need the neg Dac out voltage or neg RS232 Drive, then it can pretty much be anything. But It should be kept in -7 to -13 range, and common sense means there should be little noise on it so it does not couple into other things. BUT the circuit it's self does not care what the supply is at or what is used. The +12 on the other hand, Needs to be stable and quiet with no ripple. I found using a +15 volt supply feeding a 12V three terminal will heat slinked regulator a good way to go to keep ALL the ripple out of the +12V ws *** Hi Has anybody actually measured the supply sensitivity on the -12 volt line to see weather a 5 volt change makes any noticeable difference in the output frequency? The power on -12 is very low, so there should be negligible thermal impact from a change. Bob ___ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
