Re: [time-nuts] 510 doubler
On Fri, Jan 30, 2015 at 07:35:34PM +0100, Gerhard Hoffmann wrote: As usual, it depends. If you want absolutely deep notches, it is easy with the usual molded chokes to produce craters at 5 and 15 MHz that meet at 10 MHz, even producing some loss there. Hello. Let me sum up everything and please correct me: the square-law characteristic of devices should be avoided, so the configuration of the doubler must be some sort of ideal full wave rectifier it's better to use diode-connected transistors like the 2N because they are less noisy than Schottky diodes at frequency 40MHz (what about the normal P-N diodes?) matching is very important, so monolithic doubles or quadruples could be the right choice, provided their other characteristics are compatible and the substrate connection is not a problem bandpass filtering must be avoided because of added unwanted temperature-dependent phase shifts, so harmonic suppression should be obtained by notch filtering the notch filters could be made using quartz resonators but their high impedance versus LC ones should be taken into account and, anyway, it's difficult to find exactly tuned quartz (particularly for the higher harmonics because of the overtone cut) - the sharpness of quartz filtering is not needed anyway because the harmonics are distant enough for LC filters (what about ceramic resonators?) I add some questions. I saw that most of the doublers out there are using a center tapped transformer to obtain +-180 while the Racal circuit use a single ended input / balanced output transistor discrete differential amplifier, thus combining phase splitting with gain and impedance matching (but not isolation). That configuration should be avoided because the transformer is normally a better matched splitter? On the base of many considerations, the Racal circuit is flawed in many parts; it's anyway good enough for the counters it was designed for or the better performance of other doublers will show up? Best regards, Andrea Baldoni ___ 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] Toko web catalog
Hello. Thank you to everyone who helped me with the search of the Toko catalog. I managed to download the pages still available through the Internet Archive (the link given by David), cleaned them up, corrected the links to work offline and made a zip file. Unfortunately some images are missing; the archive never saved them, but the data are all there. Hoping it will be useful, I uploaded it on the ko4bb site. It took the name Toko_5K_7K_10K_Inductors_and_transformers_Datasheet-toko.zip (123kb) I have now gathered also much more information about old Toko transformers, so if there is general interest and Didier agree, I can upload there another (bigger) archive. Best regards, Andrea Baldoni ___ 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] Symmetricom TymServe 2100-GPS currently fails with GPS offset
Andrew Lindh writes: Use an engineering command to set it to 16: root engineering timing early_utc_leap 16 You can also set the TS2100 to add a leap second at the correct time: root timing leap 1 07/01/2015 00:00:00 Tried that, but it seems that this setting stays only for a ongoing hour. As soon the hour changes, the leap setting will be lost, UTC offset is 17 again and time has one second offset: Before hour change: 27 ? leap leap second insertion at JUL 01 2015 00:00:00.00 After hour change: 28 ? leap leap second none at NOV 15 1995 00:00:00.00 -- 73s! Esa OH4KJU ___ 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] Usefulness of high end counters for ADEV plots of oscillators
Hi Rick, Thank you, I was intending to use an external reference and it is useful to know that the OCXO options are not worth paying a lot extra for. Since I'm looking at refurbished or ebay instruments the presence or otherwise of the OCXO options is a matter of luck - if they are there it doesn't push up the cost as it would on a new unit, but it all depends on if the original purchaser needed one or not. The one thing that the OCXO option seems to buy you is a narrower PLL locking range which presumably means that less noise/jitter is added to the external reference. I am more a time acorn than a time nut at present so I'm not yet at the stage of doing serious ADEV measurements but I want to be able to assess (comparatively) different OCXOs that I have acquired and also different GPSDO approaches. Perhaps for my uses it is sufficient to have the curve from about 100 seconds on. James -Original Message- From: Richard (Rick) Karlquist rich...@karlquist.com To: jpbridge jpbri...@aol.com; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sat, 31 Jan 2015 0:14 Subject: Re: [time-nuts] Usefulness of high end counters for ADEV plots of oscillators First of all, the oven oscillator option of the 53230 is no where near as stable in ADEV as a 10811 for example. The counter itself is 1 or 2 orders of magnitude better than the built in timebase. So don't waste your money on the OCXO option when you, as a time nut, undoubtably already own something like a 10811. When I was still with Agilent, I made innumerable measurements of ADEV with a 53230 down into the low parts in 10^11, which was the DUT ADEV, not limited by the counter. I vaguely remember measuring a 10811 as a sanity check and using the internal OCXO (not knowing any better). After wasting a lot of time, I eventually measured one 10811 against another and discovered that the ADEV floor was down to 1E-12 at least, and that the internal OCXO was junk. About the only good thing about the 53230 is that it is a self contained box that makes ADEV measurements and displays them in real time without requiring an external computer with software. In 1974, HP made a computing counter (5360 I think) that did this. Customers loved this box, but the HP engineers hated the box. Therefore, no HP/Agilent counter ever did ADEV again, until the product line was offshored to engineers who didn't know any better and put the feature back in. For serious ADEV measurements, you want two DUT's offset by a few 100 Hz and mixed, as originated in the HP 5490 system. Rick Karlquist N6RK On 1/30/2015 8:38 AM, James via time-nuts wrote: Though I'm new to the list I've lurked for quite a while and from reading various posts I am in a slightly confused state as to whether buying an expensive counter (eg Keysight 53230A or a Tek fca 3100) will be useful as a measurement tool for developing a GPSDO. Given a one shot measurement resolution of 50 psecs (on the Tek which is a pendulum CNT91) means that the uncertainty is around 50E-12 at 1 sec or 5 x 10^-11 or 10^-10 in round numbers for a ADEV at 1 sec? For this noise floor to get well below 10^-11 (the sort of ADEV of an OCXO) requires the interval to be increased to nearer to 100 seconds? So does this mean that an expensive counter allows useful ADEV plots from 100 seconds on but not the lower time frames? (By useful I mean able to measure down to and below 10^-11 not down to 10^-14!) The extra cost of the 53230A over the 3100 gets down to 20 psecs so possibly reduces the period to a bit less than 100 seconds but still above 10 seconds probably? Does paying extra for an OCXO gain significantly on this basis? Have I got the basic numbers right, and if one of my main aims is to have a good instrument for playing with GPSDO development will investing in such an expensive (for an individual hobbyist) instrument buy me a useful measurement capability or would it just be good for measuring long term frequency and say 1pps jitter from the GPS? Sorry for the long post, James ___ 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] Usefulness of high end counters for ADEV plots of oscillators
Rick Very interesting on the HP5360 and that it could do ADEV. I had no idea and actually don't know how that would be done. I can appreciate the HP Engineers distaste for the 5360. Its very complex to repair. I have 5 of them with the keyboard and they work. The worlds biggest calculator by size and weight. Very good oven in them. Not to take over the thread, few ever heard of the 5360. It seems the 53230 may be just a bit lighter. OK now to go see if I can hunt down how you do adev. Regards Paul WB8TSL On Fri, Jan 30, 2015 at 7:13 PM, Richard (Rick) Karlquist rich...@karlquist.com wrote: First of all, the oven oscillator option of the 53230 is no where near as stable in ADEV as a 10811 for example. The counter itself is 1 or 2 orders of magnitude better than the built in timebase. So don't waste your money on the OCXO option when you, as a time nut, undoubtably already own something like a 10811. When I was still with Agilent, I made innumerable measurements of ADEV with a 53230 down into the low parts in 10^11, which was the DUT ADEV, not limited by the counter. I vaguely remember measuring a 10811 as a sanity check and using the internal OCXO (not knowing any better). After wasting a lot of time, I eventually measured one 10811 against another and discovered that the ADEV floor was down to 1E-12 at least, and that the internal OCXO was junk. About the only good thing about the 53230 is that it is a self contained box that makes ADEV measurements and displays them in real time without requiring an external computer with software. In 1974, HP made a computing counter (5360 I think) that did this. Customers loved this box, but the HP engineers hated the box. Therefore, no HP/Agilent counter ever did ADEV again, until the product line was offshored to engineers who didn't know any better and put the feature back in. For serious ADEV measurements, you want two DUT's offset by a few 100 Hz and mixed, as originated in the HP 5490 system. Rick Karlquist N6RK On 1/30/2015 8:38 AM, James via time-nuts wrote: Though I'm new to the list I've lurked for quite a while and from reading various posts I am in a slightly confused state as to whether buying an expensive counter (eg Keysight 53230A or a Tek fca 3100) will be useful as a measurement tool for developing a GPSDO. Given a one shot measurement resolution of 50 psecs (on the Tek which is a pendulum CNT91) means that the uncertainty is around 50E-12 at 1 sec or 5 x 10^-11 or 10^-10 in round numbers for a ADEV at 1 sec? For this noise floor to get well below 10^-11 (the sort of ADEV of an OCXO) requires the interval to be increased to nearer to 100 seconds? So does this mean that an expensive counter allows useful ADEV plots from 100 seconds on but not the lower time frames? (By useful I mean able to measure down to and below 10^-11 not down to 10^-14!) The extra cost of the 53230A over the 3100 gets down to 20 psecs so possibly reduces the period to a bit less than 100 seconds but still above 10 seconds probably? Does paying extra for an OCXO gain significantly on this basis? Have I got the basic numbers right, and if one of my main aims is to have a good instrument for playing with GPSDO development will investing in such an expensive (for an individual hobbyist) instrument buy me a useful measurement capability or would it just be good for measuring long term frequency and say 1pps jitter from the GPS? Sorry for the long post, James ___ 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] 10544A vs. 10811
I have a choice. Can I assume the 10811 is the better OCXO for phase noise and ADEV compared with the 10544A? Thanks and regards...Bill ___ 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] ***SPAM*** Re: 510 doubler
Andrea wrote: the square-law characteristic of devices should be avoided, so the configuration of the doubler must be some sort of ideal full wave rectifier I disagree strongly with this, at least where push-push JFET doublers are concerned. If you look at the schematic Bruce posted on his site, which uses a pair of J310 FETs driven into the pinch-off region, it runs the FETs from 0 to about 21mA. My circuit, when using J310s, runs the FETs from about 1mA to about 16mA. In both cases, when the FETs are conducting they are operating as common-source linear amplifiers, NOT as switches. In either case, when one FET is drawing low (or zero) current, the other one is drawing high current. The theoretical noise improvement due to running the low-current FET past the pinch-off point is, in practice, totally swamped by the noise from the other FET. In order to realize a useful reduction of noise, the FETs would have to switch hard, from off (beyond pinchoff) to full on (with Vgs=0) -- but JFETs don't work like that, unless you drive the gates hard with square waves (that is how commutating mixers such as the ones designed by Ed Oxner and the later H-mode mixers work). See below for a schematic of an Oxner mixer using a quad JFET (but note that commutating mixers generally use MOSFETs). When my circuit is normalized for 50 ohm output (by using a 4:1 transformer at the output -- which is the preferred method of driving 50 ohms with it) and the bias and drive are adjusted for the same currents as Bruce's circuit, the models predict almost identical noise from the two circuits. As a real-world check, I adjusted the bias conditions and drive on my breadboard doubler to give FET currents from 1 to about 22mA, and the measured noise decreased by a fraction of a dB. (The spurious distortion products rose somewhat, but not nearly as much as when one drives the FETs beyond pinch-off.) So no, running the FETs in Class AB or B does NOT confer a material noise advantage compared to running them in barely Class A, as my design does. It does, however, create an exponential explosion of odd-order distortion products that must be removed if the circuit is to be useful for time nuts purposes. So in my view, the barely Class A push-push JFET doubler is clearly superior to its Class AB or B cousin. it's better to use diode-connected transistors like the 2N * * * matching is very important, so monolithic doubles or quadruples could be the right choice, provided their other characteristics are compatible and the substrate connection is not a problem [NB: this applies to a mixer-based doubler, not a JFET push-push doubler.] Again, this is a theoretical advantage that is easily overshadowed in practice by the errors introduced by building one's own diode DBM. It is not impossible to build a home-brew DBM that performs as well as a good commercial DBM, but it is not easy, either. Just a small imbalance due to unequal winding spacing on the cores, small differences in stray capacitance, or geometric differences due to the packaging of the transistors used can easily create increased distortion products that are much worse than the 2 or 3dB reduction of noise you might realize. I'm not saying don't do it, just that the chances of improving things without causing collateral damage that is worse than the cure may not be high. 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] 510 doubler
I wrote: In both cases, when the FETs are conducting they are operating as common-source linear amplifiers, NOT as switches. should be, common gate linear amplifiers 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.
