Re: [time-nuts] Once again about counter calibration
Using GPSDO 10 Mhz as REF signal, I was able to calibrate OCXO. And now its potentiometer position was nether at its both extremes. The reading on 5386a (using 10 sec gate) fluctuate from 9.3M to 10.7M. Again, may be I need to wait much longer when OCXO will be stable. So, you are using a 5386A with TCXO to meaasure an OCXO, and the reading you get drifts 14 e-10 (or 1.4 e-9), nicely centered on 10 MHz. This error band includes the error of both the TCXO and the OCXO (presumably, the TCXO contributes most of this error, but you don't have enough information to conclude that yet). [This error also includes the jitter in the trigger circuitry of the 5386A, but if you are using a 10 second gate time that should be small compared to the drift of the TCXO.] I don't believe you can reasonably expect this setup to exhibit less drift than what you are seeing. In fact, I'm surprised the drift range is as low as 1.4 e-9. Waiting will probably change the center of the drift range (it will not stay symmetrically +/- 7 e-10 above and below 10.0), but not the magnitude of the range (14 e-10 peak to peak). So, I think the best approach will be using 10Mhz GPSDO as ref. signal for this counter. In another case, I'll need to wait to warm it up (the manual advised only 30 minutes. But I am not sure). Generally, a time nut would let a counter warm up for 24 to 48 hours before doing any critical work. And yes, the GPSDO is probably the most stable of the three oscillators you have (I assume you leave it running 24/7/365), so the best you will be able to do is to feed it into the 5386A's external reference input and measure the OCXO. You should see a smaller drift range than the 1.4 e-9 you are seeing now, which will indicate that most of the drift you are seeing now is due to the TCXO (and confirm the expectation noted above). Most time-nuts use a distribution amplifier to supply separately buffered copies of their best oscillator to various instruments and other equipment. In your case, you would feed the GPSDO into the distribution amp and then use the distribution amp's multiple outputs to feed the 5386A's reference input, your various radios, etc., etc. Best regards, Charles ___ 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] Once again about counter calibration
The problem with using a 1 Hz reference when looking at a nominal 10 MHz signal is that you will get a stable scope display with no drift when the input is *any* integer number of cycles/sec. So 10,000,000 Hz will give a stable display, but so will 9,999,999 Hz and 10,000,001 Hz. Unless you know that your 10 MHz signal is already within 0.5 Hz of the correct frequency, the drift method is likely to cause you to adjust to the nearest integer number of Hz, not exactly 10 MHz as you want. It's better to start out with input and reference that are the same frequency, or are related by some small integer factor. So you can compare a 10 MHz adjustable oscillator to a reference that is 1 MHz or 5 MHz or 10 MHz or 20 MHz. For a stable scope trace, connect the lower of the two frequencies to the scope trigger input, and the higher frequency to the scope waveform input. Then adjust for zero drift. Also, use an analog oscilloscope if you have one (or a digital scope with a high waveform update rate). An analog scope will clearly show a high drift rate as a smeared waveform, so you will know that you need to keep adjusting the frequency trimmer and (probably in which direction). With a low-cost digital scope, you can get beat frequencies between the drift frequency and the screen update rate that make it appear as if the input waveform is stationary, when it fact it is drifting rapidly. - Dave On Sat, Apr 25, 2015 at 11:12 PM, d0ct0r t...@patoka.org wrote: I tried to use 1PPS as Ext. trigger for the oscilloscope. I was able to stabilize signal movement. Then I tried to calibrate OCXO. However its appeared out of range (I reach end of potentiometer limit but counter still shows that OCXO is out of 10Mhz). Which kind of suspicious. Then I decide to disassemble my project to take pure 10Mhz directly from GPSDO to measure OCXO signal. Its read totally different frequency value now. So, using 1PPS didn't work for me. I tried using that GPSDO 10 Mhz as Ext. Trigger. And now I got much better result. I was able to calibrate 5386A to some extent. But my 5386 has TCXO. So, after few minutes its moving out of perfect value. May be I need to wait much longer to stabilize oscillator. I am not sure what to expect here. Using GPSDO 10 Mhz as REF signal, I was able to calibrate OCXO. And now its potentiometer position was nether at its both extremes. The reading on 5386a (using 10 sec gate) fluctuate from 9.3M to 10.7M. Again, may be I need to wait much longer when OCXO will be stable. So, I think the best approach will be using 10Mhz GPSDO as ref. signal for this counter. In another case, I'll need to wait to warm it up (the manual advised only 30 minutes. But I am not sure). And then re-calibrate it. Its time consuming. I am curious, if its practical to calibrate something like Morion MV89A and use it as signal reference for this counter ? Or OCXO still will drift out of desired frequency relatively soon ? Regards, V.P. ___ 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] Once again about counter calibration
Hi OCXO’s come in many different “flavors”. Some older units with rack mount designs may take 1 day simply to warm up. Older AT based units might take 10 minutes simply to stop pulling maximum power. Stopping the maximum power pull does *not* indicate they are done drifting. Wit an AT drift in the first 24 hours might be 5x10^-8 relative to the end of the first hour. With a good SC that has only been off power for 48 hours, you might cut that down by 10X. Note the “48 hours” above. The assumption is that the power is only briefly interrupted after being on for a long period. If the OCXO has been off power for years, time to re-stabalize is anybody’s guess. A good unit might get to the 1x10^-8 per day level in a few days. Another unit from the exact same production batch might take 5 days to get there. OCXO’s are designed to be constantly on power. They work best that way. Keep them on power for a while (a couple weeks) before trying to adjust one that has an unknown history. Bob On Apr 25, 2015, at 11:12 PM, d0ct0r t...@patoka.org wrote: I tried to use 1PPS as Ext. trigger for the oscilloscope. I was able to stabilize signal movement. Then I tried to calibrate OCXO. However its appeared out of range (I reach end of potentiometer limit but counter still shows that OCXO is out of 10Mhz). Which kind of suspicious. Then I decide to disassemble my project to take pure 10Mhz directly from GPSDO to measure OCXO signal. Its read totally different frequency value now. So, using 1PPS didn't work for me. I tried using that GPSDO 10 Mhz as Ext. Trigger. And now I got much better result. I was able to calibrate 5386A to some extent. But my 5386 has TCXO. So, after few minutes its moving out of perfect value. May be I need to wait much longer to stabilize oscillator. I am not sure what to expect here. Using GPSDO 10 Mhz as REF signal, I was able to calibrate OCXO. And now its potentiometer position was nether at its both extremes. The reading on 5386a (using 10 sec gate) fluctuate from 9.3M to 10.7M. Again, may be I need to wait much longer when OCXO will be stable. So, I think the best approach will be using 10Mhz GPSDO as ref. signal for this counter. In another case, I'll need to wait to warm it up (the manual advised only 30 minutes. But I am not sure). And then re-calibrate it. Its time consuming. I am curious, if its practical to calibrate something like Morion MV89A and use it as signal reference for this counter ? Or OCXO still will drift out of desired frequency relatively soon ? Regards, V.P. On , Scott McGrath wrote: Or feed both oscillators into a mixer and extract the difference which will be the offset of your DUT from your standard Content by Scott Typos by Siri On Apr 24, 2015, at 10:36 PM, Brent Gordon time-n...@adobe-labs.com wrote: Just feed the PPS into the scope trigger on step 2. The low repetition rate on the PPS would make this difficult on an analog scope; on a digital scope it is easy. You can use any sub-harmonic that is less than or equal the counter reference frequency (10 MHz). Brent On 4/24/2015 3:45 PM, d0ct0r wrote: Hello, The input: HP 5386A which I would like to calibrate, Well warmed Tremble Thunderbolt (1PPS only), 10 Mhz Datum OCXO (unknown accuracy), Rigol 1101E Oscilloscope. The goal is to calibrate counter to read the Datum OCXO. === Reading the manual for 5386A, there is simple schema for calibration: 1. Connect HP 5386A 10Mhz OUTPUT to Oscilloscope 2. Connect Frequency Standard to Ext. Trigger on Oscilloscope 3. Adjust the frequency on 5386A TCXO for minimum sideways movement of 10 Mhz signal However, my Trimble TB 10Mhz output is currently in use. I have only 1PPS signal available. The HP manual do not mention what exactly frequency needs to be on Frequency Standard connected to Ext. Trigger. Is there any method/option I could apply to calibrate HP counter ? Thanks ! ___ 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. -- WBW, V.P. ___ 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] Once again about counter calibration
The problem with using a 1 Hz reference when looking at a nominal 10 MHz signal is that you will get a stable scope display with no drift when the input is *any* integer number of cycles/sec. So 10,000,000 Hz will give a stable display, but so will 9,999,999 Hz and 10,000,001 Hz. Unless you know that your 10 MHz signal is already within 0.5 Hz of the correct frequency, the drift method is likely to cause you to adjust to the nearest integer number of Hz, not exactly 10 MHz as you want. One solution to this problem is to divide the 10 MHz to 1PPS and then compare the two 1PPS signals, using a 'scope or a TI counter. The horizontal sweep of your 'scope and your patience will determine the resolution of the measurement. For example, at 1 ns/div you can easily resolve a 1e-11 frequency difference within a minute. /tvb ___ 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] Once again about counter calibration
Dave, The trick is to closely synchronize your 1PPS generator, whether you use the 1970's method of a string of seven '7490 decade divider chips (common reset) or a 1900's method of a sync'able MCU divider such as a picDIV (http://www.leapsecond.com/pic/picdiv.htm). It's so simple it's irresistible. The PIC s/w is there for free. The PIC h/w is less than 1$. Happy dividing, /tvb On Apr 26, 2015, at 8:17 AM, Dave Martindale dave.martind...@gmail.com wrote: Yeah, I considered saying that. But if you don't have a TI counter, you need some way of resetting the divide-by-1e7 chain so the two 1 Hz pulses are close enough in time that you can see them on the scope at some reasonably fast sweep rate. Yes, you can used delayed sweep, but how stable is the delay? If you do have a TI counter, then the accuracy of the counter's time base also factors into the reading (though you don't really care about absolute timebase frequency, just drift). A compromise method might be to divide the 10 MHz down to 10 kHz or 1 kHz. Then the nearest adjacent wrong integer multiple of 1 Hz where the drift would be zero is 1 part in 10,000 or 1 part in 1000 off the nominal frequency. Any decent crystal is unlikely to start out 50 PPM or more off frequency, and really unlikely to be 500 PPM off frequency, so this mostly eliminates the wrong ratio problem. Yet you get one cycle of the scope input signal every 0.1 or 1 ms, giving a reasonable chance for one of those edges to drift close enough to the 1 PPS reference to measure the drift at a fast sweep rate. - Dave On Sun, Apr 26, 2015 at 5:58 AM, Tom Van Baak t...@leapsecond.com wrote: The problem with using a 1 Hz reference when looking at a nominal 10 MHz signal is that you will get a stable scope display with no drift when the input is *any* integer number of cycles/sec. So 10,000,000 Hz will give a stable display, but so will 9,999,999 Hz and 10,000,001 Hz. Unless you know that your 10 MHz signal is already within 0.5 Hz of the correct frequency, the drift method is likely to cause you to adjust to the nearest integer number of Hz, not exactly 10 MHz as you want. One solution to this problem is to divide the 10 MHz to 1PPS and then compare the two 1PPS signals, using a 'scope or a TI counter. The horizontal sweep of your 'scope and your patience will determine the resolution of the measurement. For example, at 1 ns/div you can easily resolve a 1e-11 frequency difference within a minute. /tvb ___ 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] Once again about counter calibration
Yeah, I considered saying that. But if you don't have a TI counter, you need some way of resetting the divide-by-1e7 chain so the two 1 Hz pulses are close enough in time that you can see them on the scope at some reasonably fast sweep rate. Yes, you can used delayed sweep, but how stable is the delay? If you do have a TI counter, then the accuracy of the counter's time base also factors into the reading (though you don't really care about absolute timebase frequency, just drift). A compromise method might be to divide the 10 MHz down to 10 kHz or 1 kHz. Then the nearest adjacent wrong integer multiple of 1 Hz where the drift would be zero is 1 part in 10,000 or 1 part in 1000 off the nominal frequency. Any decent crystal is unlikely to start out 50 PPM or more off frequency, and really unlikely to be 500 PPM off frequency, so this mostly eliminates the wrong ratio problem. Yet you get one cycle of the scope input signal every 0.1 or 1 ms, giving a reasonable chance for one of those edges to drift close enough to the 1 PPS reference to measure the drift at a fast sweep rate. - Dave On Sun, Apr 26, 2015 at 5:58 AM, Tom Van Baak t...@leapsecond.com wrote: The problem with using a 1 Hz reference when looking at a nominal 10 MHz signal is that you will get a stable scope display with no drift when the input is *any* integer number of cycles/sec. So 10,000,000 Hz will give a stable display, but so will 9,999,999 Hz and 10,000,001 Hz. Unless you know that your 10 MHz signal is already within 0.5 Hz of the correct frequency, the drift method is likely to cause you to adjust to the nearest integer number of Hz, not exactly 10 MHz as you want. One solution to this problem is to divide the 10 MHz to 1PPS and then compare the two 1PPS signals, using a 'scope or a TI counter. The horizontal sweep of your 'scope and your patience will determine the resolution of the measurement. For example, at 1 ns/div you can easily resolve a 1e-11 frequency difference within a minute. /tvb ___ 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] Once again about counter calibration
Hi You would need to add another power supply into the 5386 case and rig it to always be on. You would also need to fit the MV89 in there. The MV-89 pulls about 5X more power than the OCXO HP used in similar counters. It’s also roughly 5X the volume. The simple / cheap / high reliability / lazy approach is to use an external reference. Bob On Apr 24, 2015, at 11:46 PM, d0ct0r t...@patoka.org wrote: Following my request, I am curious about modding of HP 5386A. My unit has TCXO. Is it possible to replace that existed TCXO by third part OCXO ? Like Morion MV89A, for example ? -- WBW, V.P. ___ 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] Once again about counter calibration
I tried to use 1PPS as Ext. trigger for the oscilloscope. I was able to stabilize signal movement. Then I tried to calibrate OCXO. However its appeared out of range (I reach end of potentiometer limit but counter still shows that OCXO is out of 10Mhz). Which kind of suspicious. Then I decide to disassemble my project to take pure 10Mhz directly from GPSDO to measure OCXO signal. Its read totally different frequency value now. So, using 1PPS didn't work for me. I tried using that GPSDO 10 Mhz as Ext. Trigger. And now I got much better result. I was able to calibrate 5386A to some extent. But my 5386 has TCXO. So, after few minutes its moving out of perfect value. May be I need to wait much longer to stabilize oscillator. I am not sure what to expect here. Using GPSDO 10 Mhz as REF signal, I was able to calibrate OCXO. And now its potentiometer position was nether at its both extremes. The reading on 5386a (using 10 sec gate) fluctuate from 9.3M to 10.7M. Again, may be I need to wait much longer when OCXO will be stable. So, I think the best approach will be using 10Mhz GPSDO as ref. signal for this counter. In another case, I'll need to wait to warm it up (the manual advised only 30 minutes. But I am not sure). And then re-calibrate it. Its time consuming. I am curious, if its practical to calibrate something like Morion MV89A and use it as signal reference for this counter ? Or OCXO still will drift out of desired frequency relatively soon ? Regards, V.P. On , Scott McGrath wrote: Or feed both oscillators into a mixer and extract the difference which will be the offset of your DUT from your standard Content by Scott Typos by Siri On Apr 24, 2015, at 10:36 PM, Brent Gordon time-n...@adobe-labs.com wrote: Just feed the PPS into the scope trigger on step 2. The low repetition rate on the PPS would make this difficult on an analog scope; on a digital scope it is easy. You can use any sub-harmonic that is less than or equal the counter reference frequency (10 MHz). Brent On 4/24/2015 3:45 PM, d0ct0r wrote: Hello, The input: HP 5386A which I would like to calibrate, Well warmed Tremble Thunderbolt (1PPS only), 10 Mhz Datum OCXO (unknown accuracy), Rigol 1101E Oscilloscope. The goal is to calibrate counter to read the Datum OCXO. === Reading the manual for 5386A, there is simple schema for calibration: 1. Connect HP 5386A 10Mhz OUTPUT to Oscilloscope 2. Connect Frequency Standard to Ext. Trigger on Oscilloscope 3. Adjust the frequency on 5386A TCXO for minimum sideways movement of 10 Mhz signal However, my Trimble TB 10Mhz output is currently in use. I have only 1PPS signal available. The HP manual do not mention what exactly frequency needs to be on Frequency Standard connected to Ext. Trigger. Is there any method/option I could apply to calibrate HP counter ? Thanks ! ___ 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. -- WBW, V.P. ___ 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] Once again about counter calibration
Hi: I also have a HP5386, it has very limited inside space, I think the MV89 is too big to it, even MV89 is small size in familiar OCXO, so if I need mor accurate, I used a extend GPSDO for its 10M stand. Hui Zhang BA6IT Sent from my Moto X 已通过我的 Moto X 发送 2015年4月25日 上午11:46于 d0ct0r t...@patoka.org写道： Following my request, I am curious about modding of HP 5386A. My unit has TCXO. Is it possible to replace that existed TCXO by third part OCXO ? Like Morion MV89A, for example ? -- WBW, V.P. ___ 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] Once again about counter calibration
Hello, The input: HP 5386A which I would like to calibrate, Well warmed Tremble Thunderbolt (1PPS only), 10 Mhz Datum OCXO (unknown accuracy), Rigol 1101E Oscilloscope. The goal is to calibrate counter to read the Datum OCXO. === Reading the manual for 5386A, there is simple schema for calibration: 1. Connect HP 5386A 10Mhz OUTPUT to Oscilloscope 2. Connect Frequency Standard to Ext. Trigger on Oscilloscope 3. Adjust the frequency on 5386A TCXO for minimum sideways movement of 10 Mhz signal However, my Trimble TB 10Mhz output is currently in use. I have only 1PPS signal available. The HP manual do not mention what exactly frequency needs to be on Frequency Standard connected to Ext. Trigger. Is there any method/option I could apply to calibrate HP counter ? Thanks ! -- WBW, V.P. ___ 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] Once again about counter calibration
Why not use a T connector to patch the 10 MHz to two places at once? Bob On Friday, April 24, 2015 5:06 PM, d0ct0r t...@patoka.org wrote: Hello, The input: HP 5386A which I would like to calibrate, Well warmed Tremble Thunderbolt (1PPS only), 10 Mhz Datum OCXO (unknown accuracy), Rigol 1101E Oscilloscope. The goal is to calibrate counter to read the Datum OCXO. === Reading the manual for 5386A, there is simple schema for calibration: 1. Connect HP 5386A 10Mhz OUTPUT to Oscilloscope 2. Connect Frequency Standard to Ext. Trigger on Oscilloscope 3. Adjust the frequency on 5386A TCXO for minimum sideways movement of 10 Mhz signal However, my Trimble TB 10Mhz output is currently in use. I have only 1PPS signal available. The HP manual do not mention what exactly frequency needs to be on Frequency Standard connected to Ext. Trigger. Is there any method/option I could apply to calibrate HP counter ? Thanks ! -- WBW, V.P. ___ 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] Once again about counter calibration
Currently, 10 Mhz output connected to Linear LTC6957-3 to feed DDS and MCU for another purpose. Of course I am able to reconfigure (physically disconnect) it. But I am just curious if its an option to use only 1PPS for calibration. Regards, V.P. On , Bob Albert wrote: Why not use a T connector to patch the 10 MHz to two places at once? Bob On Friday, April 24, 2015 5:06 PM, d0ct0r t...@patoka.org wrote: Hello, The input: HP 5386A which I would like to calibrate, Well warmed Tremble Thunderbolt (1PPS only), 10 Mhz Datum OCXO (unknown accuracy), Rigol 1101E Oscilloscope. The goal is to calibrate counter to read the Datum OCXO. === Reading the manual for 5386A, there is simple schema for calibration: 1. Connect HP 5386A 10Mhz OUTPUT to Oscilloscope 2. Connect Frequency Standard to Ext. Trigger on Oscilloscope 3. Adjust the frequency on 5386A TCXO for minimum sideways movement of 10 Mhz signal However, my Trimble TB 10Mhz output is currently in use. I have only 1PPS signal available. The HP manual do not mention what exactly frequency needs to be on Frequency Standard connected to Ext. Trigger. Is there any method/option I could apply to calibrate HP counter ? Thanks ! -- WBW, V.P. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts [1] and follow the instructions there. Links: -- [1] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts -- WBW, V.P. ___ 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] Once again about counter calibration
Following my request, I am curious about modding of HP 5386A. My unit has TCXO. Is it possible to replace that existed TCXO by third part OCXO ? Like Morion MV89A, for example ? -- WBW, V.P. ___ 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] Once again about counter calibration
Just feed the PPS into the scope trigger on step 2. The low repetition rate on the PPS would make this difficult on an analog scope; on a digital scope it is easy. You can use any sub-harmonic that is less than or equal the counter reference frequency (10 MHz). Brent On 4/24/2015 3:45 PM, d0ct0r wrote: Hello, The input: HP 5386A which I would like to calibrate, Well warmed Tremble Thunderbolt (1PPS only), 10 Mhz Datum OCXO (unknown accuracy), Rigol 1101E Oscilloscope. The goal is to calibrate counter to read the Datum OCXO. === Reading the manual for 5386A, there is simple schema for calibration: 1. Connect HP 5386A 10Mhz OUTPUT to Oscilloscope 2. Connect Frequency Standard to Ext. Trigger on Oscilloscope 3. Adjust the frequency on 5386A TCXO for minimum sideways movement of 10 Mhz signal However, my Trimble TB 10Mhz output is currently in use. I have only 1PPS signal available. The HP manual do not mention what exactly frequency needs to be on Frequency Standard connected to Ext. Trigger. Is there any method/option I could apply to calibrate HP counter ? Thanks ! ___ 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.
