Re: [time-nuts] LPRO testing
On 01/20/2013 04:08 AM, Bob Camp wrote: Hi I just watch them with a reasonable counter that will give me 0.1 ppm resolution. Since the sweep is fairly fast, you can't have an overly long gate time. The real thing you want to catch is the frequency at each end of the sweep. It waits there long enough that you don't have to go crazy to catch it. As I suspected. I would have to switch mode for fine-tuning anyway. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LPRO testing
Hi Yes, unless you have some very unusual gear, it's tough to get a good view of the warmup / lockup sweeps *and* the performance of the LPRO after it's locked. The main questions on the lockup sweep is going to be: 1) does it make it to / past the right frequency? 2) how soon after it does get there, does it lock up? 3) if it doesn't lock up, does it do something odd as it sweeps past the right frequency? Not terribly complex. Bob On Jan 20, 2013, at 9:33 AM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 01/20/2013 04:08 AM, Bob Camp wrote: Hi I just watch them with a reasonable counter that will give me 0.1 ppm resolution. Since the sweep is fairly fast, you can't have an overly long gate time. The real thing you want to catch is the frequency at each end of the sweep. It waits there long enough that you don't have to go crazy to catch it. As I suspected. I would have to switch mode for fine-tuning anyway. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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] LPRO testing
Warren, On 01/20/2013 09:42 PM, WarrenS wrote: Magnus After you find/fix the working ones, may want to measure their Ageing rate, room temperature Tempco, and ADEV. Oh yes, that will be the interesting stuff once I'm past the initial bumps that I anticipate. These are know to have issues so I want to do a quick diagnosis so I would know how to proceed with each individual of them. Two example plots attached, one from LadyHeather using a Tbolt with the LPRO as it's ref Osc, the other is a TimeLab plot using a XOR phase comparator to test an undisciplined LPRO. To get valid ageing rate and tempco data that is good enough to measured a correctly working LPRO, using this Tbolt method, need to log at least three days and preferable a week or more of data. To measure my LPROs' ADEV which is typically ~1e-11 at 1 sec and crosses 1e-12 at ~ 200 seconds, a couple hours of data will do. Once past the initial hurdles, looking at drift and ADEV becomes interesting, so will phase-noise. TimeLab's freq plot will give a great plot of the LPRO's locked warm-up performance. For this, depending on the time period and DUT's noise and drift rate, I find setting the TimeLab's freq display filter from 10 to 1000 seconds works best. TimeLab exercises will be nice, but I hate to lock up the computer for longer runs with the TimePod. I can use the old laptop for TI.EXE exercises. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LPRO testing
I do not have a LPRO nor a schematic but all Efratom units I have played with have identical loops. They also use the 1 uF capacitor for sweeping. Adding an other larger capacitor in parallel and the sweep slows down and you can observe 127 Hz behavior. Bert Kehren In a message dated 1/20/2013 3:18:58 P.M. Eastern Standard Time, li...@rtty.us writes: Hi Yes, unless you have some very unusual gear, it's tough to get a good view of the warmup / lockup sweeps *and* the performance of the LPRO after it's locked. The main questions on the lockup sweep is going to be: 1) does it make it to / past the right frequency? 2) how soon after it does get there, does it lock up? 3) if it doesn't lock up, does it do something odd as it sweeps past the right frequency? Not terribly complex. Bob On Jan 20, 2013, at 9:33 AM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 01/20/2013 04:08 AM, Bob Camp wrote: Hi I just watch them with a reasonable counter that will give me 0.1 ppm resolution. Since the sweep is fairly fast, you can't have an overly long gate time. The real thing you want to catch is the frequency at each end of the sweep. It waits there long enough that you don't have to go crazy to catch it. As I suspected. I would have to switch mode for fine-tuning anyway. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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] LPRO testing
li...@rtty.us wrote: The main questions on the lockup sweep is going to be: 1) does it make it to / past the right frequency? 2) how soon after it does get there, does it lock up? It crosses the right frequency a few times until lockup, in both directions. According to my experience, typical lockup time for a healthy unit is 3.5min. 3) if it doesn't lock up, does it do something odd as it sweeps past the right frequency? It may get stuck at either end of the sweep span. Normally the sweept voltage (as available at the voltage monitor output) should vary between about 0.5V and 12.5V and vice-versa. If it reaches 0V or about 14V then one of the voltage comparator circuits failed, and the unit gets stuck. 0.5V and 12.5V are preset thresholds for the voltage comparators. I happened to come across both cases, and the failing components were 100K resistors. Antonio I8IOV ___ 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] LPRO testing
Further, the strangest case I had to deal with was a correct voltage sweep at the monitor output but wrong voltage at the varactor: the issue was a leaking capacitor between the above voltage rail and ground, namely C406. Antonio I8IOV li...@rtty.us wrote: The main questions on the lockup sweep is going to be: 1) does it make it to / past the right frequency? 2) how soon after it does get there, does it lock up? It crosses the right frequency a few times until lockup, in both directions. According to my experience, typical lockup time for a healthy unit is 3.5min. 3) if it doesn't lock up, does it do something odd as it sweeps past the right frequency? It may get stuck at either end of the sweep span. Normally the sweept voltage (as available at the voltage monitor output) should vary between about 0.5V and 12.5V and vice-versa. If it reaches 0V or about 14V then one of the voltage comparator circuits failed, and the unit gets stuck. 0.5V and 12.5V are preset thresholds for the voltage comparators. I happened to come across both cases, and the failing components were 100K resistors. Antonio I8IOV ___ 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] LPRO testing
Well, I believed to be answering questions from the original poster, not to questions that indeed are troubleshotting advices. Sorry Antonio Further, the strangest case I had to deal with was a correct voltage sweep at the monitor output but wrong voltage at the varactor: the issue was a leaking capacitor between the above voltage rail and ground, namely C406. Antonio I8IOV li...@rtty.us wrote: The main questions on the lockup sweep is going to be: 1) does it make it to / past the right frequency? 2) how soon after it does get there, does it lock up? It crosses the right frequency a few times until lockup, in both directions. According to my experience, typical lockup time for a healthy unit is 3.5 min. 3) if it doesn't lock up, does it do something odd as it sweeps past the right frequency? It may get stuck at either end of the sweep span. Normally the sweept voltage (as available at the voltage monitor output) should vary between about 0.5V and 12.5V and vice-versa. If it reaches 0V or about 14V then one of the voltage comparator circuits failed, and the unit gets stuck. 0.5V and 12.5V are preset thresholds for the voltage comparators. I happened to come across both cases, and the failing components were 100K resistors. Antonio I8IOV ___ 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] LPRO testing
Hi John, On 01/20/2013 10:36 PM, John Miles wrote: If you have a TimePod or 3120A you may be able to capture an LPro warmup cycle by selecting 500 Hz measurement bandwidth. You will still get drift warnings during the lock-search process but the data will probably be OK as long as the swing isn't too radical. In this case, the LPro swept about +/- 150 Hz around 10 MHz before locking up at about 120 seconds: Zooming into the frequency-difference plot reveals that it continued to settle down for the next few minutes: Quite useful :) You could get the same data from a counter, of course, just not at 1000 sample points per second. :) Naturally! :) (20+ MB .TIM file at http://www.miles.io/lpro_coldstart.zip for those interested) Handy. Thanks :) The main reason I have been asking have been to establish measurements to be done in order to figure out the failure mode(s). Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LPRO testing
Hi Watching the EFC sweep as it tries to lock can be a useful diagnostic tool. Bob On Jan 19, 2013, at 8:45 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Fellow time-nuts, As I received a box of suspect LPROs I now have a largish amount of LPROs to test through. I got the LPRO manual as well as the repair guide. Seems like I need to solder up a connector and hook a few things up. I will have to improvise on the heat-sink side until I find something useful. I would think that I would sort them into a few different piles depending on the failure modes. By external observing I should see these: 1) Heater problem (monitoring current would have heating gone or overheating) 2) Lamp problem (monitoring the lamp monitor output) 3) Lock problem (monitoring the BITE as well as frequency) 4) RF problem (monitoring the existence of RF output) What else did can people think off? I think the above would work as a systematic check-list. Now, I'd love to hear about hints and tips from you folks. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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] LPRO testing
Hi Should have been more clear. Watching the *output frequency* as the EFC sweeps and the EFC it's self can be a useful diagnostic tool. Bob On Jan 19, 2013, at 8:45 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Fellow time-nuts, As I received a box of suspect LPROs I now have a largish amount of LPROs to test through. I got the LPRO manual as well as the repair guide. Seems like I need to solder up a connector and hook a few things up. I will have to improvise on the heat-sink side until I find something useful. I would think that I would sort them into a few different piles depending on the failure modes. By external observing I should see these: 1) Heater problem (monitoring current would have heating gone or overheating) 2) Lamp problem (monitoring the lamp monitor output) 3) Lock problem (monitoring the BITE as well as frequency) 4) RF problem (monitoring the existence of RF output) What else did can people think off? I think the above would work as a systematic check-list. Now, I'd love to hear about hints and tips from you folks. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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] LPRO testing
Hi Bob, On 01/20/2013 02:53 AM, Bob Camp wrote: Hi Should have been more clear. Watching the *output frequency* as the EFC sweeps and the EFC it's self can be a useful diagnostic tool. That will be done. Would CNT-90 eye-bolling suffice or do you think TimeLab logging will be needed? Default would be CNT-90 eye-bolling as I always like to see the heat-up signature of OCXOs. It would be neat if I could log a pair of DMMs and the HP PSU along-side the TIC into the same plot. Unfortunately TimeLab isn't that tool yet. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LPRO testing
Hi I just watch them with a reasonable counter that will give me 0.1 ppm resolution. Since the sweep is fairly fast, you can't have an overly long gate time. The real thing you want to catch is the frequency at each end of the sweep. It waits there long enough that you don't have to go crazy to catch it. Bob On Jan 19, 2013, at 9:35 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Hi Bob, On 01/20/2013 02:53 AM, Bob Camp wrote: Hi Should have been more clear. Watching the *output frequency* as the EFC sweeps and the EFC it's self can be a useful diagnostic tool. That will be done. Would CNT-90 eye-bolling suffice or do you think TimeLab logging will be needed? Default would be CNT-90 eye-bolling as I always like to see the heat-up signature of OCXOs. It would be neat if I could log a pair of DMMs and the HP PSU along-side the TIC into the same plot. Unfortunately TimeLab isn't that tool yet. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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.
