Re: [time-nuts] FE5680A Calibration
Hi Drive the GPS pps into the set input on a flip flop, drive the pps from the FE into the reset input. Use the UC10 to measure the period of the waveform on the Q output. Not super high resolution, but if you are patient, you can get the job done. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of David Sent: Wednesday, March 14, 2012 7:34 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] FE5680A Calibration I picked up a gimpy Beckman UC10 universal counter not long ago for about $10 from Ebay. Even better, I just repaired a Tektronix 7D15 (it has a whole board full of those junk TI integrated circuit sockets which need to be replaced) although you need to leave an entire oscilloscope mainframe on to use it. The advantage of the later is adjustable slope, sensitivity, and triggering. On Wed, 14 Mar 2012 17:50:28 -0400, Bob Camp li...@rtty.us wrote: At least the don't mess to much with it part has sunk in. That puts you ahead of most people at this point. A usable counter should be a sub $100 sort of thing either at auction or surplus. With some careful shopping it can be a sub $40 item. On Mar 14, 2012, at 4:25 PM, Chris Stake st...@btinternet.com wrote: Hi Bob, Thanks for pointing-out the noisy output of the FE5680A. I'll probably try to lock a crystal oscillator to it. Unfortunately I don't have a suitable counter. I was hoping I could use some sort of higher frequency standard but I confess I had not really grasped the fact that the unit may well be within millihertz of the nominal frequency: too delicate to twiddle with anything other than precision equipment and long timebases. Kind regards Chris -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: 14 March 2012 16:57 To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] FE5680A Calibration Hi Do you have a dual channel counter that you can put the GPS into on the start and the FE into as the stop? The HP 5334, 5335, and 5345 are all examples of this sort of counter. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Stake Sent: Wednesday, March 14, 2012 12:49 PM To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] FE5680A Calibration Nice idea, But I haven't got a DSO and the persistence of my scope isn't good enough to view 10Mhz sampled at 1pps. Chris -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of EB4APL Sent: 14 March 2012 15:46 To: time-nuts@febo.com Subject: Re: [time-nuts] FE5680A Calibration My fast approach would be to trigger a scope with the 1 PPS from the GPS receiver and observe the how the 10 MHz output of your Rb drifts. 1 full cycle per second is 1 e-7 so you'll need to use an stopwatch to time long periods when you are fine adjusting . Building (or buying) a GPSDO allows yo to make the comparison between both 10 MHz outputs without the jitter in the GPS receiver 1 PPS. Probably others in this list can suggest more elaborated and convenient approaches to this. On 14/03/2012 16:17, Chris Stake wrote: Hello all, I purchased a FE5680A from a Chinese Ebay vendor. I have connected it to a 16.5V laptop supply, added 7805-based 5V rail and a PMOS Fet switch to drive a LED for the locked signal. I can communicate with it using the excellent Fe5680Calibrator software. As received the frequency offset is set to Zero and the unit seems to work well. I plan to put it into service as a workshop frequency reference and so would like to set it close to 10.0Mhz. I have various oscillator modules, signal generators, SDR receivers, GPS receivers, a scanner, some uncalibrated test-gear. I live in a river valley in North Devon UK so radio reception is a bit restricted but I receive digital television via a masthead amplifier and long downlead. Could someone please suggest a way of going about this? Regards Chris Stake ___ 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
[time-nuts] FE5680A Calibration
Hello all, I purchased a FE5680A from a Chinese Ebay vendor. I have connected it to a 16.5V laptop supply, added 7805-based 5V rail and a PMOS Fet switch to drive a LED for the locked signal. I can communicate with it using the excellent Fe5680Calibrator software. As received the frequency offset is set to Zero and the unit seems to work well. I plan to put it into service as a workshop frequency reference and so would like to set it close to 10.0Mhz. I have various oscillator modules, signal generators, SDR receivers, GPS receivers, a scanner, some uncalibrated test-gear. I live in a river valley in North Devon UK so radio reception is a bit restricted but I receive digital television via a masthead amplifier and long downlead. Could someone please suggest a way of going about this? Regards Chris Stake ___ 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] FE5680A Calibration
My fast approach would be to trigger a scope with the 1 PPS from the GPS receiver and observe the how the 10 MHz output of your Rb drifts. 1 full cycle per second is 1 e-7 so you'll need to use an stopwatch to time long periods when you are fine adjusting . Building (or buying) a GPSDO allows yo to make the comparison between both 10 MHz outputs without the jitter in the GPS receiver 1 PPS. Probably others in this list can suggest more elaborated and convenient approaches to this. On 14/03/2012 16:17, Chris Stake wrote: Hello all, I purchased a FE5680A from a Chinese Ebay vendor. I have connected it to a 16.5V laptop supply, added 7805-based 5V rail and a PMOS Fet switch to drive a LED for the locked signal. I can communicate with it using the excellent Fe5680Calibrator software. As received the frequency offset is set to Zero and the unit seems to work well. I plan to put it into service as a workshop frequency reference and so would like to set it close to 10.0Mhz. I have various oscillator modules, signal generators, SDR receivers, GPS receivers, a scanner, some uncalibrated test-gear. I live in a river valley in North Devon UK so radio reception is a bit restricted but I receive digital television via a masthead amplifier and long downlead. Could someone please suggest a way of going about this? Regards Chris Stake ___ 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] FE5680A Calibration
The first thing to consider is something to put the 5680 into. Search the list for temperature considerations. Basically you will need to heat sink the 5680. It can be run without, but won't last long. The technique I'm going to use it to heat sink the 5680 and with a pair of small variable speed fans (one as a backup) the inside of the box will be keep at a reasonably constant temperature with the set point based on keeping the 5680 in a safe region. There's been quite a bit of discussion on 10 MHz distribution. For now I'm thinking of using a surplus commercial video distribution amplifier. Most studio grade DA's are good to 15 MHz +- 3db. I also have a HP 5087A but its input is 5 MHz and the output cards are mostly 5MHz. A future project to convert. I have not decided if I want to put the Rb which maybe a LPRO, the Thunderbolt, and maybe a 10811 into one box or not. One idea is with them all on one box having the ability to adjust the Rb and the 10811 via the Thunderbolt, and one box can be looked at as a temp controlled 'oven' for all three. One could also put a DIY DA into the same box. -pete PS A friend and time-nut has be threatening to do a modern easy to build DA, many on the list need one. On Wed, Mar 14, 2012 at 8:17 AM, Chris Stake st...@btinternet.com wrote: Hello all, I purchased a FE5680A from a Chinese Ebay vendor. I have connected it to a 16.5V laptop supply, added 7805-based 5V rail and a PMOS Fet switch to drive a LED for the locked signal. I can communicate with it using the excellent Fe5680Calibrator software. As received the frequency offset is set to Zero and the unit seems to work well. I plan to put it into service as a workshop frequency reference and so would like to set it close to 10.0Mhz. I have various oscillator modules, signal generators, SDR receivers, GPS receivers, a scanner, some uncalibrated test-gear. I live in a river valley in North Devon UK so radio reception is a bit restricted but I receive digital television via a masthead amplifier and long downlead. Could someone please suggest a way of going about this? Regards Chris Stake ___ 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] FE5680A Calibration
Hi Consider that the noise on the 10 MHz output of the FE5680 is pretty bad. You may / may not want to propagate it all over your shop. At the very least, a simple band pass filter is needed. A better solution would be to lock a crystal oscillator up to the FE and use the output of the oscillator. It's a reasonable bet that you unit is within +/- 1x10^-10 of the right frequency. If you are lucky, it's 10X better than that. To observe it's frequency adequately to set it well, you will need to average it's output for at least a couple hundred seconds. You don't want to make it worse trying to set it closer If you are comparing to a normal GPS receiver, they have noise on their PPS output as well. To get to adequate stability / resolution you will need to average them for a while. Just how long depends on which one you have and a few other things. Best approach / lazy approach / provides adequate time for a beer: Look at the edge of the FE's pps relative to the pps out of the GPS on a scope. Note the offset on a piece of paper along with the time. Come back in an hour and repeat the process. Get a couple of points this way. The drift (if any) will show up as a linear trend. The noise will likely be in the 20 to 200 ns. At this point all you really are looking for is a noise estimate. Say the noise is 200 ns. If you do observations at a 200 second spacing you would get 1x10^-9. To get to 1x10^-12 you need to observe for about 1000X longer. 200,000 seconds is a couple of days. Yes indeed there are fancy math things try to speed things up. They don't fit under the lazy approach (there also are a few other reasons to take your time). Based on the noise estimate you get, and the calculations above, come up with a schedule. No need to get obsessive about it. All you are looking for is: read every day / every three days / once a week sort of spacing. Start logging your phase offset at what ever spacing makes sense. Take at least ten readings. Based on your readings, take a stab at correcting the FE. Adjust it and then go back to taking readings. Eventually it will be close enough. So much fun... Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Stake Sent: Wednesday, March 14, 2012 11:17 AM To: 'Discussion of precise time and frequency measurement' Subject: [time-nuts] FE5680A Calibration Hello all, I purchased a FE5680A from a Chinese Ebay vendor. I have connected it to a 16.5V laptop supply, added 7805-based 5V rail and a PMOS Fet switch to drive a LED for the locked signal. I can communicate with it using the excellent Fe5680Calibrator software. As received the frequency offset is set to Zero and the unit seems to work well. I plan to put it into service as a workshop frequency reference and so would like to set it close to 10.0Mhz. I have various oscillator modules, signal generators, SDR receivers, GPS receivers, a scanner, some uncalibrated test-gear. I live in a river valley in North Devon UK so radio reception is a bit restricted but I receive digital television via a masthead amplifier and long downlead. Could someone please suggest a way of going about this? Regards Chris Stake ___ 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] FE5680A Calibration
Nice idea, But I haven't got a DSO and the persistence of my scope isn't good enough to view 10Mhz sampled at 1pps. Chris -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of EB4APL Sent: 14 March 2012 15:46 To: time-nuts@febo.com Subject: Re: [time-nuts] FE5680A Calibration My fast approach would be to trigger a scope with the 1 PPS from the GPS receiver and observe the how the 10 MHz output of your Rb drifts. 1 full cycle per second is 1 e-7 so you'll need to use an stopwatch to time long periods when you are fine adjusting . Building (or buying) a GPSDO allows yo to make the comparison between both 10 MHz outputs without the jitter in the GPS receiver 1 PPS. Probably others in this list can suggest more elaborated and convenient approaches to this. On 14/03/2012 16:17, Chris Stake wrote: Hello all, I purchased a FE5680A from a Chinese Ebay vendor. I have connected it to a 16.5V laptop supply, added 7805-based 5V rail and a PMOS Fet switch to drive a LED for the locked signal. I can communicate with it using the excellent Fe5680Calibrator software. As received the frequency offset is set to Zero and the unit seems to work well. I plan to put it into service as a workshop frequency reference and so would like to set it close to 10.0Mhz. I have various oscillator modules, signal generators, SDR receivers, GPS receivers, a scanner, some uncalibrated test-gear. I live in a river valley in North Devon UK so radio reception is a bit restricted but I receive digital television via a masthead amplifier and long downlead. Could someone please suggest a way of going about this? Regards Chris Stake ___ 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] FE5680A Calibration
Hi Do you have a dual channel counter that you can put the GPS into on the start and the FE into as the stop? The HP 5334, 5335, and 5345 are all examples of this sort of counter. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Stake Sent: Wednesday, March 14, 2012 12:49 PM To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] FE5680A Calibration Nice idea, But I haven't got a DSO and the persistence of my scope isn't good enough to view 10Mhz sampled at 1pps. Chris -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of EB4APL Sent: 14 March 2012 15:46 To: time-nuts@febo.com Subject: Re: [time-nuts] FE5680A Calibration My fast approach would be to trigger a scope with the 1 PPS from the GPS receiver and observe the how the 10 MHz output of your Rb drifts. 1 full cycle per second is 1 e-7 so you'll need to use an stopwatch to time long periods when you are fine adjusting . Building (or buying) a GPSDO allows yo to make the comparison between both 10 MHz outputs without the jitter in the GPS receiver 1 PPS. Probably others in this list can suggest more elaborated and convenient approaches to this. On 14/03/2012 16:17, Chris Stake wrote: Hello all, I purchased a FE5680A from a Chinese Ebay vendor. I have connected it to a 16.5V laptop supply, added 7805-based 5V rail and a PMOS Fet switch to drive a LED for the locked signal. I can communicate with it using the excellent Fe5680Calibrator software. As received the frequency offset is set to Zero and the unit seems to work well. I plan to put it into service as a workshop frequency reference and so would like to set it close to 10.0Mhz. I have various oscillator modules, signal generators, SDR receivers, GPS receivers, a scanner, some uncalibrated test-gear. I live in a river valley in North Devon UK so radio reception is a bit restricted but I receive digital television via a masthead amplifier and long downlead. Could someone please suggest a way of going about this? Regards Chris Stake ___ 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] FE5680A Calibration
Hi Bob, Thanks for pointing-out the noisy output of the FE5680A. I'll probably try to lock a crystal oscillator to it. Unfortunately I don't have a suitable counter. I was hoping I could use some sort of higher frequency standard but I confess I had not really grasped the fact that the unit may well be within millihertz of the nominal frequency: too delicate to twiddle with anything other than precision equipment and long timebases. Kind regards Chris -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: 14 March 2012 16:57 To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] FE5680A Calibration Hi Do you have a dual channel counter that you can put the GPS into on the start and the FE into as the stop? The HP 5334, 5335, and 5345 are all examples of this sort of counter. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Stake Sent: Wednesday, March 14, 2012 12:49 PM To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] FE5680A Calibration Nice idea, But I haven't got a DSO and the persistence of my scope isn't good enough to view 10Mhz sampled at 1pps. Chris -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of EB4APL Sent: 14 March 2012 15:46 To: time-nuts@febo.com Subject: Re: [time-nuts] FE5680A Calibration My fast approach would be to trigger a scope with the 1 PPS from the GPS receiver and observe the how the 10 MHz output of your Rb drifts. 1 full cycle per second is 1 e-7 so you'll need to use an stopwatch to time long periods when you are fine adjusting . Building (or buying) a GPSDO allows yo to make the comparison between both 10 MHz outputs without the jitter in the GPS receiver 1 PPS. Probably others in this list can suggest more elaborated and convenient approaches to this. On 14/03/2012 16:17, Chris Stake wrote: Hello all, I purchased a FE5680A from a Chinese Ebay vendor. I have connected it to a 16.5V laptop supply, added 7805-based 5V rail and a PMOS Fet switch to drive a LED for the locked signal. I can communicate with it using the excellent Fe5680Calibrator software. As received the frequency offset is set to Zero and the unit seems to work well. I plan to put it into service as a workshop frequency reference and so would like to set it close to 10.0Mhz. I have various oscillator modules, signal generators, SDR receivers, GPS receivers, a scanner, some uncalibrated test-gear. I live in a river valley in North Devon UK so radio reception is a bit restricted but I receive digital television via a masthead amplifier and long downlead. Could someone please suggest a way of going about this? Regards Chris Stake ___ 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] FE5680A Calibration
Hi At least the don't mess to much with it part has sunk in. That puts you ahead of most people at this point. A usable counter should be a sub $100 sort of thing either at auction or surplus. With some careful shopping it can be a sub $40 item. Bob On Mar 14, 2012, at 4:25 PM, Chris Stake st...@btinternet.com wrote: Hi Bob, Thanks for pointing-out the noisy output of the FE5680A. I'll probably try to lock a crystal oscillator to it. Unfortunately I don't have a suitable counter. I was hoping I could use some sort of higher frequency standard but I confess I had not really grasped the fact that the unit may well be within millihertz of the nominal frequency: too delicate to twiddle with anything other than precision equipment and long timebases. Kind regards Chris -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: 14 March 2012 16:57 To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] FE5680A Calibration Hi Do you have a dual channel counter that you can put the GPS into on the start and the FE into as the stop? The HP 5334, 5335, and 5345 are all examples of this sort of counter. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Stake Sent: Wednesday, March 14, 2012 12:49 PM To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] FE5680A Calibration Nice idea, But I haven't got a DSO and the persistence of my scope isn't good enough to view 10Mhz sampled at 1pps. Chris -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of EB4APL Sent: 14 March 2012 15:46 To: time-nuts@febo.com Subject: Re: [time-nuts] FE5680A Calibration My fast approach would be to trigger a scope with the 1 PPS from the GPS receiver and observe the how the 10 MHz output of your Rb drifts. 1 full cycle per second is 1 e-7 so you'll need to use an stopwatch to time long periods when you are fine adjusting . Building (or buying) a GPSDO allows yo to make the comparison between both 10 MHz outputs without the jitter in the GPS receiver 1 PPS. Probably others in this list can suggest more elaborated and convenient approaches to this. On 14/03/2012 16:17, Chris Stake wrote: Hello all, I purchased a FE5680A from a Chinese Ebay vendor. I have connected it to a 16.5V laptop supply, added 7805-based 5V rail and a PMOS Fet switch to drive a LED for the locked signal. I can communicate with it using the excellent Fe5680Calibrator software. As received the frequency offset is set to Zero and the unit seems to work well. I plan to put it into service as a workshop frequency reference and so would like to set it close to 10.0Mhz. I have various oscillator modules, signal generators, SDR receivers, GPS receivers, a scanner, some uncalibrated test-gear. I live in a river valley in North Devon UK so radio reception is a bit restricted but I receive digital television via a masthead amplifier and long downlead. Could someone please suggest a way of going about this? Regards Chris Stake ___ 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. ___ 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] FE5680A Calibration
On Wed, Mar 14, 2012 at 8:17 AM, Chris Stake st...@btinternet.com wrote: Hello all, I purchased a FE5680A from a Chinese Ebay vendor. I have connected it to a 16.5V laptop supply, added 7805-based 5V rail and a PMOS Fet switch to drive a LED for the locked signal. I can communicate with it using the excellent Fe5680Calibrator software. As received the frequency offset is set to Zero and the unit seems to work well. What you need to do is build a GPSDO using your FE5680A as the O. You can use digital logic or a human in the control loop. Either way it works the same. Get a 7400 series flip flop A 74AC74 costs about 50 cents. Wite it so the PPS for the GPS flips it on and the next edge of the 10MHz out from the FE5680 re-sets the signal. A simple XOR can also work. Now what you do is measure the time the signal is high. The classic way is to use the signal to charge a capacitor then measure the voltage on the cap. So now you can use a DMM to measure time. The controller adjusts the FE5680A's frequency so as to keep the time the signal is high (and the voltage on the cap) at some arbitrary fixed value People have built the above using all kinds of methods, from pure analog to micro controllers, 7400 logic and even a human in the loop. If you want to build a working system fast look at using an Arduino and divide the 10Mhz signal down by at least 10 or 20 so that (1) the speed is compatible with solderless breadboards and the flip flop's output will stay high longer and will be easier to measure. Chris Albertson Redondo Beach, California ___ 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] FE5680A Calibration
I picked up a gimpy Beckman UC10 universal counter not long ago for about $10 from Ebay. Even better, I just repaired a Tektronix 7D15 (it has a whole board full of those junk TI integrated circuit sockets which need to be replaced) although you need to leave an entire oscilloscope mainframe on to use it. The advantage of the later is adjustable slope, sensitivity, and triggering. On Wed, 14 Mar 2012 17:50:28 -0400, Bob Camp li...@rtty.us wrote: At least the don't mess to much with it part has sunk in. That puts you ahead of most people at this point. A usable counter should be a sub $100 sort of thing either at auction or surplus. With some careful shopping it can be a sub $40 item. On Mar 14, 2012, at 4:25 PM, Chris Stake st...@btinternet.com wrote: Hi Bob, Thanks for pointing-out the noisy output of the FE5680A. I'll probably try to lock a crystal oscillator to it. Unfortunately I don't have a suitable counter. I was hoping I could use some sort of higher frequency standard but I confess I had not really grasped the fact that the unit may well be within millihertz of the nominal frequency: too delicate to twiddle with anything other than precision equipment and long timebases. Kind regards Chris -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: 14 March 2012 16:57 To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] FE5680A Calibration Hi Do you have a dual channel counter that you can put the GPS into on the start and the FE into as the stop? The HP 5334, 5335, and 5345 are all examples of this sort of counter. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Stake Sent: Wednesday, March 14, 2012 12:49 PM To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] FE5680A Calibration Nice idea, But I haven't got a DSO and the persistence of my scope isn't good enough to view 10Mhz sampled at 1pps. Chris -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of EB4APL Sent: 14 March 2012 15:46 To: time-nuts@febo.com Subject: Re: [time-nuts] FE5680A Calibration My fast approach would be to trigger a scope with the 1 PPS from the GPS receiver and observe the how the 10 MHz output of your Rb drifts. 1 full cycle per second is 1 e-7 so you'll need to use an stopwatch to time long periods when you are fine adjusting . Building (or buying) a GPSDO allows yo to make the comparison between both 10 MHz outputs without the jitter in the GPS receiver 1 PPS. Probably others in this list can suggest more elaborated and convenient approaches to this. On 14/03/2012 16:17, Chris Stake wrote: Hello all, I purchased a FE5680A from a Chinese Ebay vendor. I have connected it to a 16.5V laptop supply, added 7805-based 5V rail and a PMOS Fet switch to drive a LED for the locked signal. I can communicate with it using the excellent Fe5680Calibrator software. As received the frequency offset is set to Zero and the unit seems to work well. I plan to put it into service as a workshop frequency reference and so would like to set it close to 10.0Mhz. I have various oscillator modules, signal generators, SDR receivers, GPS receivers, a scanner, some uncalibrated test-gear. I live in a river valley in North Devon UK so radio reception is a bit restricted but I receive digital television via a masthead amplifier and long downlead. Could someone please suggest a way of going about this? Regards Chris Stake ___ 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. ___ 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
