[time-nuts] Re; Motorola MC68HC11 Crystal
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] 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] Portable Time Standard
Hello Petr and others, Thank you for the suggestions. I have several DS3231 modules running. I was able to adjust one to 0.04 PPM fast, which is more than good enough for my requirement of one second a month (this is at a constant temperature, but these RTC chips are supposed to be temperature compensated). I can read and write the DS3231 registers with a Raspberry Pi. Unfortunately, the RPi kernel sends time to the RTC every 11 1/2 minutes. This time is usually moderately accurate, but I have measured errors of up to 0.264 second, which is unacceptable. Does anyone have suggestions for a very low power controller and display for this RTC integrated circuit? The DS3231 has a 1 Hz square wave output that could signal the controller to read and display the time and date from the DS3231. The controller could sleep between updates, which would conserve batteries. Thanks again for all the suggestions, Joe By the way, the manufacturer of the high accuracy marine chronometer I was considering will not send specifications for other than 22 +/- 1 degree C. These DS3231 modules are a complete clock On 2/17/2019 3:46 PM, Petr Titěra wrote: > Hello, > > as I've said these are quite new, cheap RTC modules. There is DS3231SN > on them. Based on markings they were manufactured somewhere in 2008 but > I've bought them recently. > > I have two those modules. Both connected using I2C. > > First module is connected to Orange Pi sitting on my table. Pi is > running NTP and is controlled by NEO-6M GPS module (not timing, I know > butat this level accuracy of PPS signal should be enough). > > I measure in 10 seconds intervals difference between system time (which > I consider stable in long term) and time reported by RTC chip as > reported by adjtimex in compare mode. > > This is a little bit naive setup because timing from RTC is noisy but in > long run (its running for 25 days now) it should give me reasonable results. > > I did modify offset register. Again using naive approach. I've let run > unmodified module for one day and from that I did compute offset required. > > For second module I'm meassuring just now I don't care about time > reported and meassure only interval between rising edge of its PPS > pulses and PPS pulses from another GPS. Again for this measurement I > consider GPS PPS signal as stable. > > This second one is a little bit worse (or may be wrongly calibrated) but > I still get about 0.3PPM from my measurements. > > Petr Titera > > > > > Dne 17. 2. 2019 v 19:00 Joe Hobart napsal(a): >> Hello Petr, >> >> Your accuracy results are impressive. I have questions: >> >>What manufacture or brand DS3231 do you have? >> >>What do you use to communicate with the DS3231 and display time? >> >>How long has your DS3231 been running? >> >>Have you changed the crystal aging offset register(s) to compensate for >> crystal aging? >> >> Thank you, >> Joe >> >> >> On 2/15/2019 12:51 PM, Petr Titěra wrote: >>> Hello, >>> >>> sorry to reopen this old thread but it took me some time to measure. As >>> I've said I have one RTC module sitting right on my desk in my room >>> where temperatures can go anywhere between 3C and 20C. >>> >>> Using naive method of comparison of time difference between system time >>> and RTC module I get time difference only about 4.487869e-02 seconds in >>> 22 days. >>> >>> Petr Titera >>> >>> Dne 14. 1. 2019 v 16:11 Joe Hobart napsal(a): Hello Petr, I have not found a low power RTC chip that will keep 1 second a month with changes in temperature. This clock will be used to synchronize a portable communications system. Thank you, Joe On 1/13/2019 2:23 PM, Petr Titěra wrote: > I will probably sound dumb but did you consider cheap RTC chips? I have > one based on DS3231 currently on my table and although its is specified > to have precision +/-2PPM my seems to be in range about 0.5PPM right > from package with possibility to do some corrections. > > Petr Titera > > Dne 11. 1. 2019 v 20:57 Joe Hobart napsal(a): >> I need a relatively lightweight, self powered, portable clock accurate >> to 1 >> second per month. Temperatures may range from 10 to 35 C; altitude from >> 1000 to >> 7000 feet. Although expensive, some of the marine quartz chronometers >> appear to >> meet this requirement. ~0.3 PPM. >> >> Does anyone have any experience with these devices? >> >> If so, has anyone tried to detect the probably weak magnetic field >> generated by >> the clock mechanism for time comparison purposes? >> >> Thanks, >> Joe, W7LUX >> --- This email has been checked for viruses by AVG. https://www.avg.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 instruc
[time-nuts] Lady Heather treats me badly.
Try starting with the /rxk command line option to force Lucent KSx mode. Depending upon which side you are connected to you may also have to use /br=baud_rate to force the baud rate. One side runs at the default 19200 baud, the other runs at 9600 baud. If you got the source .zip file from ke5fx.com that is the older version. Try v6 Beta from the link in: http://www.eevblog.com/forum/metrology/lady-heather-v6-beta-for-windows-exe/ ___ 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] Smaller, and smaller antennas
On 3/6/19 5:33 AM, Bill Slade wrote: My calculation was a bit hasty. Q_rad is around 123, not 7e6 (misplaced factor of 2pi). Still pretty bad, tho'. So, we have 1/24 -1/123=1/Qloss or Qloss = 25; typical of what you'd find in a lumped LC circuit. Cheers after all, a good way to get a return loss no worse than 6dB is a 3dB pad.. From: time-nuts on behalf of Bill Slade Sent: Wednesday, March 6, 2019 10:32 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Smaller, and smaller antennas The Chu-Harrington limit for passive antennas (ones without active, non-Foster circuits) states that for small antennas Q_rad>lambda^3/(2pi a)^3. at 2.4GHz, lambda = 12.5cm. For an antenna of a=4mm dominant dimension, Q_rad>7e6! If a VSWR BW of 100 MHz is measured at the feedpoint (Q_tot approx 24) and we remember that 1/Q_tot = 1/Q_rad + 1/Q_loss, we see that the Q factor is dominated by antenna losses and radiation efficiency is very poor. My feeling is that the feed network on the PCB will radiate more than this antenna. It would not be the first time that I have seen electrically small antennas that exhibit suspiciously substantial VSWR bandwidth that are like resistors than antennas. Cheers, Bill ___ 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] Synthesized Signal Generator query
E44xx-AP/DP are a bit rubbish in PN department. I have tested a few units at 1GHz and the results were within 1-2dB from the datasheet, so have a look there. Don't even bother with -A/D models. If you are looking for HP 8664A/8644B class performance, have a look at IFR/Aeroflex/Marconi 2041 and 2042. Yes, they sometimes can be had for $1000. Leo > From: "Don@True-Cal" > I have my sights on an HP 8664A with Opt. 004 Low Phase Noise and want to > keep the purchase around $1000... > Can anyone give me advise on any similar low phase noise source that > is not so big and heavy. I like the looks and size of the E44xx series but > do they come even close to the signal purity of the 8664A. ___ 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] Synthesized Signal Generator query
On 3/6/19 7:44 AM, Don@True-Cal wrote: Hello all, I have my sights on an HP 8664A with Opt. 004 Low Phase Noise and want to keep the purchase around $1000. This signal generator meets all my requirements except being able to play table tennis on the top due to its size. Can anyone give me advise on any similar low phase noise source that is not so big and heavy. I like the looks and size of the E44xx series but do they come even close to the signal purity of the 8664A. Non HP, Agilent like Anritsu is also a consideration but that really opens up a host of unknowns. Any words of advice greatly appreciated. Regards, Don what frequency range do you need? the venerable 8664A is 100k to 3G. Just so folks know what phase noise you're shooting for: at 1 GHz, -110dBc @ 1kHz out, -135 @ 10kHz out, -150 @ 100k, -160 @ 1 M ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Lady Heather treats me badly.
Hi, yesterday I did install LH on my Linux system: got the zip file, unpacked it, compiled LH and after the usual ado I was able to connect to my Lucent KS-24361 pair. But somehow it looks like she's slowly dying: first the azimuth/strength display disappears; later the clock , the info in the upper left; then the traces of the DAC etc become boring: after some hours just one green line. Increasing the display size leads to crash. F11 immediately and each time I tried. The message then is "Stack thrashing detected - heather terminated". The compiler adds some known constants around the allocated variables and when they do not stay constant it assumes that the program writes outside of its allocated data area. Did that happen somewhere else? Any Ideas? best regards, Gerhard (But the singing Monk fits Ash Wednesday. :-) ) -- I called it with: gerhard@silver:~/work/heather$ heather -rx -b2 -tz=1CET -ta -vh -id=/dev/ttyUSB0 This is the system: gerhard@silver:~$ inxi -v7 System: Host: silver Kernel: 4.10.0-38-generic x86_64 (64 bit gcc: 5.4.0) Desktop: Cinnamon 3.6.7 (Gtk 3.18.9-1ubuntu3.3) dm: lightdm Distro: Linux Mint 18.3 Sylvia Machine: Mobo: ASUSTeK model: P8Z68-V PRO GEN3 v: Rev 1.xx Bios: American Megatrends v: 0402 date: 11/16/2011 CPU: Quad core Intel Core i7-2600K (-HT-MCP-) cache: 8192 KB flags: (lm nx sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx) bmips: 27289 clock speeds: min/max: 1600/3800 MHz 1: 1600 MHz 2: 1599 MHz 3: 1615 MHz 4: 1599 MHz 5: 1753 MHz 6: 1648 MHz 7: 1599 MHz 8: 1599 MHz Memory: No dmidecode memory data: try newer kernel. (16 GB RAM) Graphics: Card: NVIDIA GF110 [GeForce GTX 570] bus-ID: 01:00.0 chip-ID: 10de:1081 Display Server: X.Org 1.18.4 drivers: nvidia (unloaded: fbdev,vesa,nouveau) Resolution: 2560x1440@59.95hz GLX Renderer: GeForce GTX 570/PCIe/SSE2 GLX Version: 4.5.0 NVIDIA 384.130 Direct Rendering: Yes Audio: Card-1 NVIDIA GF110 High Definition Audio Controller . There is no other load than Firefox and Thunderbird. ___ 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
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 On Tue, 5 Mar 2019 17:58:58 -0500, Joe Leikhim wrote: > 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. ___ 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] Synthesized Signal Generator query
Hello all, I have my sights on an HP 8664A with Opt. 004 Low Phase Noise and want to keep the purchase around $1000. This signal generator meets all my requirements except being able to play table tennis on the top due to its size. Can anyone give me advise on any similar low phase noise source that is not so big and heavy. I like the looks and size of the E44xx series but do they come even close to the signal purity of the 8664A. Non HP, Agilent like Anritsu is also a consideration but that really opens up a host of unknowns. Any words of advice greatly appreciated. Regards, Don ___ 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] Smaller, and smaller antennas
On 3/5/19 11:11 PM, Bruce Griffiths wrote: 2.4/0.1 = 24 not 240 !!! Indeed,you're right, but still, pretty high Q.. Bruce On 06 March 2019 at 17:36 jimlux wrote: ___ 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] Smaller, and smaller antennas
My calculation was a bit hasty. Q_rad is around 123, not 7e6 (misplaced factor of 2pi). Still pretty bad, tho'. So, we have 1/24 -1/123=1/Qloss or Qloss = 25; typical of what you'd find in a lumped LC circuit. Cheers From: time-nuts on behalf of Bill Slade Sent: Wednesday, March 6, 2019 10:32 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Smaller, and smaller antennas The Chu-Harrington limit for passive antennas (ones without active, non-Foster circuits) states that for small antennas Q_rad>lambda^3/(2pi a)^3. at 2.4GHz, lambda = 12.5cm. For an antenna of a=4mm dominant dimension, Q_rad>7e6! If a VSWR BW of 100 MHz is measured at the feedpoint (Q_tot approx 24) and we remember that 1/Q_tot = 1/Q_rad + 1/Q_loss, we see that the Q factor is dominated by antenna losses and radiation efficiency is very poor. My feeling is that the feed network on the PCB will radiate more than this antenna. It would not be the first time that I have seen electrically small antennas that exhibit suspiciously substantial VSWR bandwidth that are like resistors than antennas. Cheers, Bill From: time-nuts on behalf of Bruce Griffiths Sent: Wednesday, March 6, 2019 8:11 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Smaller, and smaller antennas 2.4/0.1 = 24 not 240 !!! Bruce > On 06 March 2019 at 17:36 jimlux wrote: > > > On 3/5/19 3:05 PM, Charles Steinmetz wrote: > > Ho, hum, yet another fantastical claim for magical gain from a > > tiny-for-wavelength antenna. > > > > See the many discussions of same by Kurt N. Sterba over the last several > > decades, among many, many others. > > > > The laws of physics are stubborn things > > > these don't violate the theoretical limits.. 100 MHz BW at 2.4 GHz is > pretty high Q (240). > > What I'm interested in is the internal construction - lambda at 2.4 GHz > is 122 mm, and these things are 3x3x4mm. If you tried to dielectrically > load a half wavelength from 61 down to 3mm, that's a factor of 20, which > implies an epsilon of 400. Clearly, that's not what they're doing. > > I'm a bit suspicious about that long feedline in the test fixture. > > > Johansen has lots of these in various frequencies and sizes > https://www.johansontechnology.com/antennas > > Tons of WiFi (2.45 GHz) antennas in all sizes and shapes. > > GPS/GLONASS antennas too > https://www.johansontechnology.com/datasheets/1575AT54A0010/1575AT54A0010.pdf > 12x4mm > > > > > > > > Best regards, > > > > Charles > > > > > > On 3/5/2019 1:48 PM, jimlux wrote: > >> On 3/5/19 9:33 AM, Gregory Beat via time-nuts wrote: > >>> No, this is not an “L-band”, GNSS antenna ... BUT it demonstrates the > >>> shrinking size. > >>> > >>> NEW Molex 206513 Antenna for 2.4 GHz, 3x3x4 mm in size. > >>> Less than $1.00 for quantity 1, both Mouser and Digi-Key now stocking. > >>> https://www.digikey.com/en/product-highlight/m/molex/2-4-ghz-ceramic-antenna > >>> > >>> > >>> > >>> Molex’s 206513 series is a 2.4 GHz embedded ceramic antenna with high > >>> efficiency over 55% on all frequency bands. This miniature SMT ceramic > >>> component requires a very small (4 mm x 4 mm) keep-out area and is > >>> designed to be mounted directly at the corner of the main device PCB. > >>> It has a frequency range of 2.4 GHz - 2.5 GHz, return loss of <-6 dB, > >>> and peak gain (max) 3.6 dBi. It features an omnidirectional radiation > >>> pattern. > >>> > >> > >> One needs to carefully look at the 55% claim with these kinds of things. > >> Are they including that in the gain, 50% efficiency is a gain hit of > >> 3dB? Peak gain of 3.6dBi (is that circular or linear?) (is that > >> directivity, or gain?). Does the efficiency count the 25% of the power > >> reflected back from the 6dB return loss? > >> > >> https://www.molex.com/pdm_docs/ps/2065130001-PS.pdf is more about > >> packaging > >> > >> https://www.molex.com/pdm_docs/as/2065130001-AS.pdf has the antenna > >> patterns.. > >> > >> > >> > >> Also, what's the axial ratio off boresight... > >> > >> ___ > >> 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. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://l
Re: [time-nuts] Newbie alert! Just acquired a Datum FTS-4040A
Taka welcome to the time-nuts. Though I have no details on the Cesium its always good to meet a new time-nut. You have been lurking in the shadows to go from the basic systems to the Cesium. Nice. I am sure you will find help here in the group. Regards Paul WB8TSL On Tue, Mar 5, 2019 at 10:34 PM Taka Kamiya via time-nuts < time-nuts@lists.febo.com> wrote: > Hello Time-nuts I'd like to join your club. > I've been lurking for quite some time. During this time, I went to Xtal > oscillator to OCXO to GPSDO to Rubidium to GPSD Rb to TODAY, Cesium > standard. I thought this would be a good time to stop lurking and start > talking. > The Cesium unit in question is Datum FTS-4040A. I bought it on cheap. I > have no evidence that Cs tube has ever been replaced but it locks in 6 > minutes and it is quite stable. It must be a basic unit because RS232 port > is not wired (connector is there), 1 pps is not there, and only output > available are 1, 5, and 10MHz. > > I would first like to collect manuals. I went to my "usual places" and > did not find any. I did find one for 4040B but the part I really need are > missing on mine and standard on B. First goal is to enable RS232C so I can > monitor. MONITOR connector is there but this is just for relay outputs for > major errors, etc. > > If anyone can help, I'd be very appreciative. I also would like to meet > fellow FTS-4040A owners and exchange notes. > > Thanks - > Taka in Orlando FL > --- > (Mr.) Taka Kamiya > I'm stuck in a wormhole Hello, worms! > ___ > 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] Smaller, and smaller antennas
The Chu-Harrington limit for passive antennas (ones without active, non-Foster circuits) states that for small antennas Q_rad>lambda^3/(2pi a)^3. at 2.4GHz, lambda = 12.5cm. For an antenna of a=4mm dominant dimension, Q_rad>7e6! If a VSWR BW of 100 MHz is measured at the feedpoint (Q_tot approx 24) and we remember that 1/Q_tot = 1/Q_rad + 1/Q_loss, we see that the Q factor is dominated by antenna losses and radiation efficiency is very poor. My feeling is that the feed network on the PCB will radiate more than this antenna. It would not be the first time that I have seen electrically small antennas that exhibit suspiciously substantial VSWR bandwidth that are like resistors than antennas. Cheers, Bill From: time-nuts on behalf of Bruce Griffiths Sent: Wednesday, March 6, 2019 8:11 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Smaller, and smaller antennas 2.4/0.1 = 24 not 240 !!! Bruce > On 06 March 2019 at 17:36 jimlux wrote: > > > On 3/5/19 3:05 PM, Charles Steinmetz wrote: > > Ho, hum, yet another fantastical claim for magical gain from a > > tiny-for-wavelength antenna. > > > > See the many discussions of same by Kurt N. Sterba over the last several > > decades, among many, many others. > > > > The laws of physics are stubborn things > > > these don't violate the theoretical limits.. 100 MHz BW at 2.4 GHz is > pretty high Q (240). > > What I'm interested in is the internal construction - lambda at 2.4 GHz > is 122 mm, and these things are 3x3x4mm. If you tried to dielectrically > load a half wavelength from 61 down to 3mm, that's a factor of 20, which > implies an epsilon of 400. Clearly, that's not what they're doing. > > I'm a bit suspicious about that long feedline in the test fixture. > > > Johansen has lots of these in various frequencies and sizes > https://www.johansontechnology.com/antennas > > Tons of WiFi (2.45 GHz) antennas in all sizes and shapes. > > GPS/GLONASS antennas too > https://www.johansontechnology.com/datasheets/1575AT54A0010/1575AT54A0010.pdf > 12x4mm > > > > > > > > Best regards, > > > > Charles > > > > > > On 3/5/2019 1:48 PM, jimlux wrote: > >> On 3/5/19 9:33 AM, Gregory Beat via time-nuts wrote: > >>> No, this is not an “L-band”, GNSS antenna ... BUT it demonstrates the > >>> shrinking size. > >>> > >>> NEW Molex 206513 Antenna for 2.4 GHz, 3x3x4 mm in size. > >>> Less than $1.00 for quantity 1, both Mouser and Digi-Key now stocking. > >>> https://www.digikey.com/en/product-highlight/m/molex/2-4-ghz-ceramic-antenna > >>> > >>> > >>> > >>> Molex’s 206513 series is a 2.4 GHz embedded ceramic antenna with high > >>> efficiency over 55% on all frequency bands. This miniature SMT ceramic > >>> component requires a very small (4 mm x 4 mm) keep-out area and is > >>> designed to be mounted directly at the corner of the main device PCB. > >>> It has a frequency range of 2.4 GHz - 2.5 GHz, return loss of <-6 dB, > >>> and peak gain (max) 3.6 dBi. It features an omnidirectional radiation > >>> pattern. > >>> > >> > >> One needs to carefully look at the 55% claim with these kinds of things. > >> Are they including that in the gain, 50% efficiency is a gain hit of > >> 3dB? Peak gain of 3.6dBi (is that circular or linear?) (is that > >> directivity, or gain?). Does the efficiency count the 25% of the power > >> reflected back from the 6dB return loss? > >> > >> https://www.molex.com/pdm_docs/ps/2065130001-PS.pdf is more about > >> packaging > >> > >> https://www.molex.com/pdm_docs/as/2065130001-AS.pdf has the antenna > >> patterns.. > >> > >> > >> > >> Also, what's the axial ratio off boresight... > >> > >> ___ > >> 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. ___ 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] Smaller, and smaller antennas
2.4/0.1 = 24 not 240 !!! Bruce > On 06 March 2019 at 17:36 jimlux wrote: > > > On 3/5/19 3:05 PM, Charles Steinmetz wrote: > > Ho, hum, yet another fantastical claim for magical gain from a > > tiny-for-wavelength antenna. > > > > See the many discussions of same by Kurt N. Sterba over the last several > > decades, among many, many others. > > > > The laws of physics are stubborn things > > > these don't violate the theoretical limits.. 100 MHz BW at 2.4 GHz is > pretty high Q (240). > > What I'm interested in is the internal construction - lambda at 2.4 GHz > is 122 mm, and these things are 3x3x4mm. If you tried to dielectrically > load a half wavelength from 61 down to 3mm, that's a factor of 20, which > implies an epsilon of 400. Clearly, that's not what they're doing. > > I'm a bit suspicious about that long feedline in the test fixture. > > > Johansen has lots of these in various frequencies and sizes > https://www.johansontechnology.com/antennas > > Tons of WiFi (2.45 GHz) antennas in all sizes and shapes. > > GPS/GLONASS antennas too > https://www.johansontechnology.com/datasheets/1575AT54A0010/1575AT54A0010.pdf > 12x4mm > > > > > > > > Best regards, > > > > Charles > > > > > > On 3/5/2019 1:48 PM, jimlux wrote: > >> On 3/5/19 9:33 AM, Gregory Beat via time-nuts wrote: > >>> No, this is not an “L-band”, GNSS antenna ... BUT it demonstrates the > >>> shrinking size. > >>> > >>> NEW Molex 206513 Antenna for 2.4 GHz, 3x3x4 mm in size. > >>> Less than $1.00 for quantity 1, both Mouser and Digi-Key now stocking. > >>> https://www.digikey.com/en/product-highlight/m/molex/2-4-ghz-ceramic-antenna > >>> > >>> > >>> > >>> > >>> Molex’s 206513 series is a 2.4 GHz embedded ceramic antenna with high > >>> efficiency over 55% on all frequency bands. This miniature SMT ceramic > >>> component requires a very small (4 mm x 4 mm) keep-out area and is > >>> designed to be mounted directly at the corner of the main device PCB. > >>> It has a frequency range of 2.4 GHz - 2.5 GHz, return loss of <-6 dB, > >>> and peak gain (max) 3.6 dBi. It features an omnidirectional radiation > >>> pattern. > >>> > >> > >> One needs to carefully look at the 55% claim with these kinds of things. > >> Are they including that in the gain, 50% efficiency is a gain hit of > >> 3dB? Peak gain of 3.6dBi (is that circular or linear?) (is that > >> directivity, or gain?). Does the efficiency count the 25% of the power > >> reflected back from the 6dB return loss? > >> > >> https://www.molex.com/pdm_docs/ps/2065130001-PS.pdf is more about > >> packaging > >> > >> https://www.molex.com/pdm_docs/as/2065130001-AS.pdf has the antenna > >> patterns.. > >> > >> > >> > >> Also, what's the axial ratio off boresight... > >> > >> ___ > >> 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. ___ 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.
