Re: [time-nuts] Si5351A harmonics question
Have you read this?? https://www.qrp-labs.com/ultimate3/u3info/u3pa.html -- 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.
Re: [time-nuts] Garmin GPS12XL V3.51
John; Try the tool Peter found. I thought the GPS-12 lacked a serial port and the GPS-12XL had both a serial port and external antenna port. Both good to have for a differential station. "Message: 9 Date: Mon, 8 Apr 2019 01:52:20 + From: John Reid To:"time-nuts@lists.febo.com" Subject: Re: [time-nuts] Garmin GPS12XL V3.51 Message-ID: Content-Type: text/plain; charset="utf-8" I checked today the GPS12XL I have, and that came up with a date in August 99, before dying a few minutes later. Firmware 4.57. The only thought I had was that the GPS 12 (still working, still showing "19" as the year) was bought new around 2002 with a differential receiver. Perhaps there was something different for that? John" -- 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.
Re: [time-nuts] Garmin GPS12XL V3.51
I just checked the Garmin site and indeed there are upgrades to versions 4.60 and 3.53. It seems that since I have V3.51 I can jump to 3.53 but not 4.60. I assume my hardware precedes yours. "Mine had the batteries out for about a year.? Put some fresh ones in, turned it on and set it outside for several minutes. It located position and is showing today's date and time just fine.? Software version on mine is 4.58. Wes" -- 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.
Re: [time-nuts] Garmin GPS12XL V3.51
Thanks! I don't ever think I relied on the date in the unit. It is going to get some use soon. I would have no idea what to replace it with. Next I need to check out my Symmetricom / /Datum 9390/-/6000/ EXACTIME next. The antenna has been off \for a while. It was updated some years back to what was the latest and last version. On 4/6/2019 1:04 AM, Peter Putnam wrote: From the Garmin web-site at: https://support.garmin.com/en-US/?faq=jXw3hvTdo24PunZy4yOpX8=87=date%20error=topics GPS 12 Time and Date are Incorrect We’ve identified an issue with this product that causes the date and/or time to be wrong after the GPS Rollover on April 6th, 2019. However, all functions not dependent on date and/or time will continue to work normally. Due to the age of the device we have determined we will not fix this issue. *What does that mean for my Garmin**?* * The date and/or time determined by the GPS will be wrong * Position, velocity, navigation, and all other functionality not dependent on date and/or time will continue to work normally *What is GPS Week Rollover?* The GPS satellite system communicates the date via a week number that is limited to 1024 weeks (about 20 years). On April 6th, 2019 the week numbers broadcast by the satellites will “rollover” to zero. If GPS receivers don’t account for this rollover in their software, it will calculate the wrong date and/or time. On 4/5/2019 8:40 PM, Joe Leikhim wrote: Just checked my wonderful Garmin GPS12XL tonight. before midnight UTC I checked navigation and UTC time and all was well. I did not bother to check date for some reason. Well now April 6 2019 at 03:39:19 UTC I see the time is 21 August 99 and no apparent way to change. The navigation and time seem correct. I heard there was a way to reset these to current date. Any thoughts? Can I still use this as a tool for gathering waypoints with precision? <http://www.avg.com/email-signature?utm_medium=email_source=link_campaign=sig-email_content=emailclient> Virus-free. www.avg.com <http://www.avg.com/email-signature?utm_medium=email_source=link_campaign=sig-email_content=emailclient> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> -- 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] Garmin GPS12XL V3.51
Just checked my wonderful Garmin GPS12XL tonight. before midnight UTC I checked navigation and UTC time and all was well. I did not bother to check date for some reason. Well now April 6 2019 at 03:39:19 UTC I see the time is 21 August 99 and no apparent way to change. The navigation and time seem correct. I heard there was a way to reset these to current date. Any thoughts? Can I still use this as a tool for gathering waypoints with precision? -- 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.
Re: [time-nuts] 4.19 MHz xtal
That same frequency 4.19304 MHz was used in the infamous Lockerbie flight 103 bom b timer, the Swiss made MEBO MST-13. The design of that timer was such that it could be optioned to be set up to hours. Why I know this? I was reading the history of this the other day and FBI's involvement etc. -- Joe K4SAT ___ 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] Re; Motorola MC68HC11 Crystal (Robert LaJeunesse)
Thanks Bob, Bob L, and Hugh.
I will look further into the exact specs of this 68HC11. Being this is a
small densely packed portable radio, the circuit foils are very tiny,
the stray capacitance is probably lower than typical design. Good point
on using the div/4 pin to measure the clock and to isolate the pulling
circuit. I will take a spare mother board and make a test jig for the
capacitors. I will have to search for some 15 pf crystals as this is an
unusual package.
I have in past changed these crystals with OEM parts without trouble.
When they fail, by listening with a SW radio, instead of a clean tone
you get what sounds like RTTY which I interpret roughly as "A quick
Brown Fox Wants you To Change the Crystal Now Please". {:^) But now
without a ready supply of qualified OEM parts and the cheap replacements
not working on several radios, I am chasing myself.
--
Joe K4SAT
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[time-nuts] Re; Motorola MC68HC11 Crystal
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.
Re: [time-nuts] Motorola MC68HC11 Crystal
Hi Bob; Jim; After I wrote that I did take a look at RS232 serial specs and yes, they are quite permissive. The programmer I have is simply an IBM PS2/E "pizza box" which is a 486 machine running DOS. Motorola was not very competent in their design of radio service software and as such, the speed of the PC processor can affect the serial connection. That said, I use this same computer, cables and RIB (RS232 to TTL) interface box on many of the same radios without a problem. It is so critical that I have a back up PS2/E because no modern computer will do. The radio service manual points to the crystal in the event of serial communications error. I would not be surprised if the designers of the software were targeting a much tighter timing window than sensible industry standards. So I am back to the question as to my part substitution being proper as they are a common failure component because these radios, though built to MIL-810D standards, get dropped often. I have not as yet encountered "birdies" because I have been unable to load the frequencies I wish to use in these few "broken" radios. Generally, when working properly, these radios normally don't suffer from RF design problems as they were top tier radios at the time. In fact, the portable products made since are inferior. This is the work zone: http://www.leikhim.com/attachments/Image/P1130492a.JPG Joe K4SAT "Async communications will usually tolerate an timing error of about 0.5 bit time in 10 bits or about 5%. So if your oscillator is within 1% (10,000 ppm) you should be OK in that regard. I suspect your serial communication problem is coming from someplace else. Maybe the radio needs real RS-232 voltages, or you have a bad interface chip or power supply for the RS-232, or you need a null modem cable that swaps the Rx and Tx data lines." "Hi First off, the programmer will work with any of the crystals you are talking about. You should be fine at 0.1% which would be +/- 7.4 KHz relative to 7.3728 MHz. Indeed you should find that serial com will work fine at offsets even greater than this. In terms of birdies - does the radio work? If not is it an IF issue or a front end problem? If none of the replacement crystals oscillate, that’s probably a good sign that the problem is not the crystal ….. Bob" -- 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] Motorola MC68HC11 Crystal
It seems some Crystal experts are on line, so here goes with my question. I have this microcomputer circuit (attached) that is in a Motorola Systems Saber radio. It contains a 68HC11 uC that requires Y400 which is a 7.3728 MHz crystal. Motorola no longer provides an OEM replacement for this part number 4805664G32. The description is simply "XTAL ANTIRES". -- Is that Parallel Resonant? These are those tubular 3 x 8 mm style like the 32Khz crystals used in early watches. There are two critical stability requirements of this crystal. _First _it runs the external RS232 programmer at 9600 baud. If bad the radio cannot be read or written to, and _secondly_ the harmonics could fall on operating channels. The network of Q403/L400 and C409 are to shift/pull the frequency where a known harmonic might occur. -- I don't know the normal stray load this network imparts. So far I have purchased some generic crystals from e-bay but they don't seem to be solving the immediate problem which is serial communications error. The crystal I removed from circuit oscillated at 7.3708 MHz per the CW zero beat on my Icom shortwave radio. (I know, yes, it is set to WWV) or 2 KHz low. The 10 replacement crystals sampled in at around 2.47 KHz low. An OEM crystal that I have (the last one) 4.36 KHz low. In my estimation, these parts should be within 30 ppm or +/- 222 Hz I do not know if the crystal pull network is running when I made these measurements. It is a possibility. It is switched in and out depending upon the radio RX frequency. I have no control over those until the radio is read and rewritten to which I cannot in this condition. --- The E-bay generic parts: Frequency: 7.3728Mhz Frequency Tolerance: ±30ppm Load Capacitance: 18pF Mounting Type: Through Hole - Am I using the wrong load capacitance for the application? Here are my assumptions: CL=(24pf x 24pf)/24pf+24pf) + 6pf (stray is a guesstimate) = 18 pf There is not enough board space to add parts. My estimation of stray capacitance may be high. I am trying to get to square one and buy the correct parts. Or maybe this is as good as it gets and my problem is elsewhere? -- 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.
Re: [time-nuts] MEMS oscillators
Thanks that was a very cool presentation. Amazing that they made a sustainable commercial success out of something so wildly impractical. And the fact they made incremental improvements on the concept instead of giving it up for some different scheme is amazing. I got a sense that the engineer I met was doing something similar with a spinning acrylic disc. Maybe same modulation technique with a solid instead of a liquid hydrocarbon. I will have to research this some more. I don't recall his name, we (My employer Motorola) needed an expert witness at the time and this guy was probably from IEEE. I was there to give him some technical input on an 800 MHz communications system sale that was involved in a legal contest. Joe On 10/31/2018 5:54 PM, Julien Goodwin wrote: Reminds me a little of the crazy Eidophor projectors. "An Eidophor was a television projector used to create theater-sized images. The name Eidophor is derived from the Greek word-roots ‘eido’ and ‘phor’ meaning 'image' and 'bearer' (carrier). Its basic technology was the use of electrostatic charges to deform an oil surface." https://www.youtube.com/watch?v=3-BvMcqEc98 https://en.wikipedia.org/wiki/Eidophor On 31/10/18 04:39, Joe Leikhim wrote: This is fascinating. I am a bit skeptical if this actually happened. I had an opportunity to meet an engineer that was involved with early HDTV development. Apparently early in his career he invented a color projection CRT for cinema. It had some sort of target inside of it (I think plastic) that was subjected to the electron beam but would outgas hydrogen in significant amounts and that hydrogen would ionize in the electron beam which was undesired. So they incorporated a band of titanium around the neck of the tube and the titanium apparently allows hydrogen to collect and migrate through it even though there is a vacuum inside the tube. It worked as intended. Then the Chinese tried to replicate the design and did not use a titanium band because they had no idea it had a purpose. Their tubes failed miserably. --- This email has been checked for viruses by AVG. https://www.avg.com -- 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.
Re: [time-nuts] MEMS oscillators
This is fascinating. I am a bit skeptical if this actually happened. I had an opportunity to meet an engineer that was involved with early HDTV development. Apparently early in his career he invented a color projection CRT for cinema. It had some sort of target inside of it (I think plastic) that was subjected to the electron beam but would outgas hydrogen in significant amounts and that hydrogen would ionize in the electron beam which was undesired. So they incorporated a band of titanium around the neck of the tube and the titanium apparently allows hydrogen to collect and migrate through it even though there is a vacuum inside the tube. It worked as intended. Then the Chinese tried to replicate the design and did not use a titanium band because they had no idea it had a purpose. Their tubes failed miserably. -- 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.
