Re: [time-nuts] 20th year of time nuts mailing list
Hi Tom, All, Thank you for sharing such a great remembrance! At about five years subscribed I'm a newcomer and certainly at early stages of my time-nuttery journey, but none the less time-nuts remains my favourite 'net mailing list for all the reasons you outline - the exceptionally high SNR, fascinating discourse and just plain lovely bunch of folk that are involved. Thank you to Tom and all who keep it ticking over and to all that contribute to the discussions. The very best for 2021 and beyond vy 73 Hugh VK3YYZ/AD5RV On 1/1/21 4:02 pm, Tom Van Baak wrote: Hello time nuts, Ah, it is 2021-01-01 (JD 2459215.5, MJD 59215) which is nice because that means it's not 2020 anymore. One reason I've been looking forward to 2021 is that it's now officially the 20th year of the time nuts mailing list. So this is a note to say *thank you* to everyone for making it so amazing over the years. I get comments all the time about this mailing list; its depth, its high SNR, its focus, its vast archive of quality postings, and especially, the community that evolved around the list. On the web the phrase "time nut" is now a proper noun, sometimes an adjective, or occasionally a diagnosis or disease. Never in my wildest dreams did I think any of this would happen. I thought my early interest in nixie tubes, clocks, electronics, and precise timing might be a passing phase, and that the frequency of eBay purchases would fade. But no. This turns out to be an incredibly wide, deep, interesting, and rewarding hobby. The mailing list started with 6 people (half of whom are still active) and we now have 1850 members. [1] Speaking of history, and also to put time-nuts into perspective, I'd like to mention that leapsecond.com (tvb) and febo.com (jra) predate Y2K (2000), wikipedia (2001), facebook (2004), youtube (2005), twitter (2006), reddit (2006), iPhone (2007), duckduckgo (2008), gmail (2004, 2009), eevblog (2009), instagram (2010), snapchat (2011), outlook (2012), and literally millions of other web sites and mailing lists. When this all started for us it was WWV on short-wave, ACTS by phone, Loran-C, GOES, WWVB, GPS, Win98, dial-up, and my search engine was altavista.dec.com. It's scary to think how much has changed in 20 years. Fun fact: I started leapsecond.com so I could post the results of a Y2K Colorado visit to NIST. If the world was going to crash I was going to be at ground zero, with a camera. [2] Anyway, stay safe, stay healthy, stay timely. Here's to a new decade and a happy new year to all of us. /tvb [1] http://leapsecond.com/time-nuts.htm#history [2] http://leapsecond.com/y2k/ ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Quartzlock E10-MRX
Hiya, I'd wondered this also - my (limited) experience of Rbs are the LPROs and they definitely need a heatsink (I have a nice story to share about getting some made one day which I must write up, but I digress) Curious, I dug around a bit and only data I can find is a two pager on the manufacturer website - https://www.quartzlock.com/product/Rubidium/rubidium-oscillators/E10-MRX The packaging itself doesn't appear to be designed with heatsinking in mind, but perhaps there is an implicit expectation of convection cooling at least to keep it manageable ? Any idea what case temperature you're seeing @Richard ? Cheers, Hugh On 1/9/20 5:01 pm, Matthias Welwarsky wrote: On Dienstag, 1. September 2020 07:15:34 CEST Richard Katsch wrote: Hello All, I have acquired a Quartzlock E10-MRX Rb 10 MHz standard. It appears to lock and produce a nice sine wave that stays in phase with my Trimble Tbolt for a time which exceeds my attention span!!! It does however get hot in operation. As this is my first experience with a Rb standard I don’t know whether this is normal or indicates that I need a heat sink. Any comments would be appreciated. They're supposed to run hot, but excess temperature will degrade the stability and shorten the lifetime of the electronics. It's hard to recommend what heatsink they require if you have no documentation. Typically you'll need one. My LPRO-101 need a heatsink with < 2K/W of thermal resistance to keep the temperature in check. BR, Matthias Regards Richard Katsch VK2EIK ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] eLORAN in the Antipodes ? (was: Re: eLORAN will be on the air GRI 99600)
Hiya, Thank you for all the thoughtful replies on list and a couple received off list too. There is at least one VLF station in north western Australia which I think will be close enough to at least warrant the experiments, so will get myself set up with a loop antenna and suitable SDR and see what eventuates! Thanks all again, vy 73 Hugh ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] eLORAN in the Antipodes ? (was: Re: eLORAN will be on the air GRI 99600)
Hi, Been following this thread with the usual mixture of joy, awe and wonder (truly!) - fantastic stuff :) My read of the situation is that there is next to no chance of receiving any meaningful signal at the VLF frequencies in question down here in Melbourne - a great circle path of some 10,000 mi / 16000 km ? Cheers, Hugh ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Re; Motorola MC68HC11 Crystal
Hiya, A quick observation, though I'm mindful we may be drifting (sorry...) from the charter of time-nuts somewhat. I worked with 'HC11s a fair bit when they were current and seem to recall there were some subtle variations on the load capacitance requirements for the different variants (68HC811E2 vs 68HC11A1 etc. etc) It may be worth tracking down the electrical specs datasheet for the specific variant you are working with and comparing this with what you have to hand. Apologies if I'm preaching to the choir so speak though! Kind Regards/vy 73 Hugh On 7/3/19 06:47, Bob kb8tq wrote: Hi Load capacitance on a crystal is not at all easy to guess from the “stuff” hanging off of an MCU chip. There’s simply to much inside the chip that you have no way of knowing about. If indeed you *need* a very accurate crystal, it gets custom made for whatever that particular circuit happens to do. Generally that is taken care of with a PPM offset on the spec drawing. Rather than being +/- 30 ppm at some load, it will be +150 to +210 ppm. At least that’s the way Motorola always used to do it ….. Bob On Mar 7, 2019, at 1:45 AM, Joe Leikhim wrote: The circuit was an attachment and it showed 24 pf caps on the legs of the micro. It appears it is being scrubbed in the mailserver. Am I using the correct load capacitance for the application? Here are my assumptions: CL=(24pf x 24pf)/24pf+24pf) + 6pf (stray is a guesstimate) = 18 pf On 3/7/2019 1:41 AM, Joe Leikhim wrote: Roger, does the 18 pf load, crystal I have chosen for replacement seem correct for the design (attached)? Joe e: "Greetings Joe, Except for the difference in the marked frequency, there is no difference between the so-called "parallel resonant" and "series resonant" crystals. There is a minute difference in the physical dimensions and/or the angle of the cut(s) relative to the crystallographic axes to hit the desired frequency. The description of the OEM part "XTAL ANTIRES" shows that it is "parallel resonant" with the capacitance specified by the crystal manufacturer (typically 20 pF (sometimes less), 30 pF, or 50 pF) appearing in parallel with the crystal. This is the reason behind the use of a small-value variable capacitance in parallel with the crystal to trim the frequency to exactly that specified or desired at constant temperature though the trim range is relatively small. The design of crystals is something of a "black art". The so-called "series resonant" crystals are sometimes described as for use in a "resonant" mode while the so-called "parallel resonant" crystals are sometimes described as for use in an "anti-resonant" mode. This is technical gibberish but the "parallel resonant" and "series resonant" descriptions are a useful guide for the designer of the amplifier in which the crystal acts as narrow band filter in the feedback circuit and controls the frequency of the resultant oscillation. There are many considerations, such as the drive level (particularly for physically very small and very large crystals!) which have to be considered but if the equipment used to work correctly in the long term it is unlikely that there is a problem with the crystal. From your description, I doubt if the fault is in the crystal and you will need to look elsewhere for the fault. I hope that this may help you." Regards, Roger -- Joe Leikhim Leikhim and Associates Communications Consultants Oviedo, Florida jleik...@leikhim.com 407-982-0446 WWW.LEIKHIM.COM ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
