Re: [time-nuts] Frequency counter recommendations
Hi, Although they are rather less common and more expensive than the ones you mentioned, Fluke/Philips 6681 counters are also very good. Nominal resolution is 50ps single shot and 1ps repetitive. No RS232, but GPIB and a rather basic analogue output are standard. On Mon, 19 Mar 2007 22:24:46 -0800, you wrote: Hi all, I have a run-of-the-mill frequency counter (8 digits, 0.1 and 1.0 sec gate, no reference oscillator output or ext. input) and would like to upgrade to something better. I would initially like to measure frequencies in the 10 MHz or below range with a resolution of better than 0.1 Hz. From reading this list have picked out a HP 5334 or a Racal-Dana 1991/1992. Some of these have been recently on ebay, but that is not my preferred source, the seller often does not state the options installed, as well as the typical ebay problems. Are there others someone would recommend, used? -Dave D. ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
[time-nuts] 59501A GPIB D/A PRGRMR
Hello the Time Nuts group, perhaps it is not the right place to look for such things, but I am searching already a long time, w/o any positive results, the user and as well the service manual for the HP-59501A GPIB D/A PRGRMR, a programmable DC-source . One could get the impression it was never manufactured, at Agilent I just get the answer that this product is obsolete, they do not have a manual, but I do have such thing and I want to play with it (discrete setup of a regulator loop), but without the command list and some hints on running it I feel lost. Could anybody give some help perhaps with a pdf copy? Many thanks ia, Arnold ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Hello
Yes, others working with pendulums have also discovered that they end up making crude thermometers, barometers, or seismometers instead of a good clock. Still, not a reason to give up. But you know you have a world-class pendulum clock when, after having solved every other perturbation, you can see the effects of lunar tides in your data (as your good pendulum clock demonstrates it is also a fair gravimeter). That seems like a neat threshold. Are current pendulum clocks good enough to notice tides? When was the first published paper? If not, how close? -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] 59501A GPIB D/A PRGRMR
These folks list manuals for the HP-59501A. They can be a bit spendy, but they are original manuals, not copies. http://yourmanualsource.com/ On Tue, 27 Mar 2007 18:44:28 +0200, Arnold Tibus [EMAIL PROTECTED] wrote: Hello the Time Nuts group, perhaps it is not the right place to look for such things, but I am searching already a long time, w/o any positive results, the user and as well the service manual for the HP-59501A GPIB D/A PRGRMR, a programmable DC-source . -- kc0ukk at msosborn dot com ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Hello
Yes, others working with pendulums have also discovered that they end up making crude thermometers, barometers, or seismometers instead of a good clock. Still, not a reason to give up. But you know you have a world-class pendulum clock when, after having solved every other perturbation, you can see the effects of lunar tides in your data (as your good pendulum clock demonstrates it is also a fair gravimeter). That seems like a neat threshold. Are current pendulum clocks good enough to notice tides? When was the first published paper? If not, how close? Yes, it is a neat benchmark. Not a few modern clock makers have tried to reproduce or improve on the old masters. It turns out a pendulum clock needs to be accurate (stable) to 1e-7 or 1e-8 for tau from an hour to a day in order for it to detect tides. See this article I wrote a while back on the subject: Lunar/Solar Tides and Pendulum Clocks (part 1) http://www.leapsecond.com/hsn2006/ch1.htm Not sure what you mean by current pendulum clocks. I think modern commercial pendulum clocks are nowhere as accurate as the state-of-the-art pendulum clocks of the 1920's. Quartz clocks in the 30's and atomic clocks in the 50's put an end to the market for ultra precise pendulum clocks. /tvb ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Hello
Yes, others working with pendulums have also discovered that they end up making crude thermometers, barometers, or seismometers instead of a good clock. Still, not a reason to give up. But you know you have a world-class pendulum clock when, after having solved every other perturbation, you can see the effects of lunar tides in your data (as your good pendulum clock demonstrates it is also a fair gravimeter). That seems like a neat threshold. Are current pendulum clocks good enough to notice tides? When was the first published paper? If not, how close? Yes, it is a neat benchmark. Not a few modern clock makers have tried to reproduce or improve on the old masters. It turns out a pendulum clock needs to be accurate (stable) to 1e-7 or 1e-8 for tau from an hour to a day in order for it to detect tides. See this article I wrote a while back on the subject: Lunar/Solar Tides and Pendulum Clocks (part 1) http://www.leapsecond.com/hsn2006/ch1.htm Not sure what you mean by current pendulum clocks. I think modern commercial pendulum clocks are nowhere as accurate as the state-of-the-art pendulum clocks of the 1920's. Quartz clocks in the 30's and atomic clocks in the 50's put an end to the market for ultra precise pendulum clocks. /tvb My work with a pendulum seems to point to the need to know the exact phase and amplitude of the pendulum as being a sticking point. The pendulum can be mounted firmly, with no yielding or flexing of brackets on a masonry mount bedded well into the ground. The pendulum can be made mechanically stable with accurately fitted joints between shaft and bob, and shaft and suspension. The pendulum can be excited with a minute magnet and an air cored coil to drive it with a few nanowatts. The pendulum can be shielded from air currents and vibrations. However accurate signals for phase and amplitude measurement with accuracy of microseconds for phase and microns for amplitude seem to be the challenges that must be met, this information is necessary to generate the pendulum drive so that the pendulum is the only frequency determining element. Compensation for temperature and barometric pressure are do-able, although the legendary clocks were in a vacuum (more or less) and in underground clock vaults kept at constant temperature. I still have hopes of getting great performance from a room temperature clock at ambient pressure. See http://ph.groups.yahoo.com/group/synchronome/photos/view/c1ba?b=1 cheers, Neville Michie ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
