Re: [time-nuts] Antennas for Symettricom 2500 Time Source
On 6/9/2018 12:05 PM, Bruce Hunter via time-nuts wrote: Has anyone stumbled across the 12V antennas for Symmetricom 2500 Time Source units. I have a Symmetricom "Replacement GPS Antenna Kit" P/N 142-614-50 which consists of "one wide range 5-12 VDC L1 antenna" and 50 feet of Belden 9104 coax terminated with a BNC. Plus the hardware and stub mast to fix it to a vent pipe or similar. I don't know what system this antenna was designed for but the 5-12V spec is interesting. Dan - ac6ao ___ 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] nuts about position
I would be quite interested in the results of this test from something like a Ublox 6T or 8 unit. Please keep us posted. Dan On 6/5/2018 2:35 PM, time-nuts-requ...@febo.com wrote: The next thing I want to try is a receiver self-survey vs the post processed results... I may be able to kludge up a test that does a self-survey / precision survey / post processed survey and compare the results of the methods on the same data set. ___ 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] FS -hp- 5370 "Time Nuts Processor" board + +
Board is spoken for, thanks, Dan ___ 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] FS -hp- 5370 "Time Nuts Processor" board + +
Bought some time around 2013 and not used if this is any use to anyone please contact me direct. No reasonable offer refused. I also have a 5370B to go with it but that will have to be picked up in Santa Monica CA. $100 with an A parts unit and a few spare boards rescued from the gold scrap dealers. Dan ___ 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] time-nuts Digest, Vol 166, Issue 44
Mark, Ditto this. On 6T's and M8T's both. The 6T's do have an odd issue once in a while, right at the roll over limit from +10.whatever nS to -10.whatever nS, sometimes the sawtooth value comes in with the wrong sign. We were playing with the 6T's in a GPSDO, against a good crystal it stuck out really well in the graph. A software check in the GPSDO looks for this and fixes it. Seemed like it happened about once a week to once a month type timeframe. Have you noticed this in your hardware? Dan On 5/21/2018 3:21 PM, time-nuts-requ...@febo.com wrote: Message: 10 Date: Mon, 21 May 2018 19:21:25 + From: Mark Sims<hol...@hotmail.com> To:"time-nuts@febo.com" <time-nuts@febo.com> Subject: [time-nuts] NEO-M8N vs. NEO-M8T Message-ID: <sn1pr11mb1024d7811062897bd74308eece...@sn1pr11mb1024.namprd11.prod.outlook.com> Content-Type: text/plain; charset="iso-8859-1" It looks like you have slipped a decimal point somewhere (also that "ps" label is wrong). I have an M8N running here and the report sawtooth errors are all within a ± 10 ns span. (and LEA-5T is ± 5ns). ___ 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] Motorola GPS Antenna?
On 5/21/2018 8:24 AM, Clint Jay wrote: Found on eBay with no further information, can anyone identify? https://www.ebay.co.uk/itm/EX-MOD-Motorola-Antenna/323177970249?hash=item4b3ee87a49:g:tHIAAOSwUCZavUAe It looks like the standard "Marine" antenna, probably 5v, loads of gain (30 dB?), like the one I have up on my roof. There should be a part number under the rubber gasket if you want to ask the seller to have a look. Dan ___ 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] Datametrics SP-100 Time Code Generator
Hello, I'm looking for a schematic and/or service manual for a Datametrics SP-100, a 1970s-era rack-mount IRIG time code generator. According to the Time Nuts archives, Dave Brown (ZL3FJ) was looking for this information back in 2005 but as far as I can see received no reply. I have found references to its use in a timing distribution system but haven't found service information that would allow component level repair. Does anyone have, or know of a source for, technical information on this unit? Thanks! Cheers, Dan --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ___ 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] Racal 9475 Rubidium
On 5/3/2018 9:55 AM, Bob kb8tq wrote: Hi You *really* need to keep the baseplate of the FRK series devices down. Their reliability drops quite a bit as you go from 40 to 50 to 60 C on the baseplate. I would avoid boosting the input voltage without a very good heatsink ( or heatsink + fan ) setup. I just measured mine after about two hours of warm up, the case sides (which also are a sort of sink) measure around 33C, and the rear heat sink around 34C in a fairly chilly (17C :^) ) southern California room. I don't think it's ever going to cook the FRK which has been working when needed, as I just discovered, since 2001. Dan ___ 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] Racal 9475 Rubidium
On 5/3/2018 7:38 AM, Adrian Godwin wrote: What sort of heatsink does it need ? Do you need the original part or would a lightly-machined generic module do ? At the time, at least in the UK, it was a very common extrusion, often used for power supplies etc., and in fact I see two on the back of big Astron supplies under my bench. I had some in my "junk box" that even had the mounting holes in the correct places. If anyone needs it I can take photographs of the back of my 9475 with the heatsink fitted. Dan ___ 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] Racal 9475 Rubidium
On 5/1/2018 2:18 AM, Paul Bicknell wrote: As I have just bought a Racal 9475 Rubidium and it has problems Is there any stock faults ? What is the life of the rubidium standard? The Racal manual for this only covers the support stuff. Your problem is almost certainly with the Rb module; these were some variety of FRK, either FRK-L or -H. These are repairable without much difficulty, but obviously you will need the manual for it. In the FRK there is a crystal that will have aged, and a free running audio oscillator around 8 kHz in the servo unit that may well need attention. I did fix mine some ten or more years ago and since then it has worked when needed. I wouldn't worry about the lamp yet before checking the rest of it. Dan ___ 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] nuts about position
Hi, Anecdotal response. A few years back we played with using handheld garmin units (GPSMAP 62st) for locating property lines and corners. We averaged for 6 to 12 hours at known standards (section corners). This data was used to subdivide the section for property corner locations, and these corners were marked. The method for marking was to park the GPS close to the calculated corner location in Lat/Lon. Then we let the GPS survey for the same 6-12 hour period, corrected the GPS position and repeated until the desired corner was located. A year or two later due to a power line upgrade, many of the properties were surveyed professionally. We're in a small community and we got chatting with the surveyors. We helped them find roads/trails to get to section corners they needed to get to. They in turn helped us by marking the property corners in question with survey grade equipment (They said accurate to within an inch). The handheld GPS units were within about a foot or so of the professional units. Obvious concerns aside, what we were really doing was dividing relatively short distances (1 mile) between existing point into even shorter distances between the points. The limiting factor was really number of digits in the average reported Lat/Lon positions from the GPS. That said, with a few good reference points (section corners, or other standards) near the telescope and some time using a good handheld GPS and some careful math you should be able to drill down close to 0.3m level of accuracy. We did want to repeat the tests with timing mode receivers set to average for 48 hours, but haven't got around to it yet. Dan On 4/25/2018 12:00 PM, time-nuts-requ...@febo.com wrote: Message: 6 Date: Wed, 25 Apr 2018 07:56:14 -0700 From: "Tom Van Baak"<t...@leapsecond.com> To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Subject: [time-nuts] nuts about position Message-ID: <2E0CF8A1D3C64D58BA771539C620ABE9@pc52> Content-Type: text/plain; charset="iso-8859-1" List -- I had a recent query by a researcher who would like to pinpoint the location of his telescope(s) within 0.3 meters. Also (he must be a true scientist) he wants to do this on-the-cheap. He may have timing requirements as well, but that's another posting. So I toss the GPS question to the group. Surely some of you have crossed the line from precise time to precise location? How easy, how cheap, how possible is it to obtain 0.3 m accuracy in 3D position? When we run our GPSDO in survey mode how accurate a position do we get after an hour, or even 24 or 48 hours? And here I mean accurate, not stable. Have any of you compared that self-reported, self-survey result against an independently measured professional result or known benchmark? Do you know if cheap ublox 5/6/7/8 series receivers are capable of 1 foot accuracy given enough time? If not, what improvement would -T models and RINEX-based web-service post-processing provide? It that's still not close enough to 0.3 m, is one then forced to use more expensive multi-frequency (L1/L2) or multi-band (GPS, GLONASS, Galileo) to achieve this level of precision? If so, how cheaply can one do this? Or is the learning curve more expensive than just hiring an survey specialist to make a one-time cm-level measurement for you? Something tells me 1 foot accuracy in position is possible and actually easier than 1 ns accuracy in time. I'm hoping some of you can help recommend solution(s) to the researcher's question or shed light on this interesting challenge. Thanks, /tvb ___ 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] Introduction & GPSDO Question
I'm mainly interested in creating a reasonable 10mHz standard for my various pieces of test equipment here at home. To that end I've purchased and received an Ebay "Trimble Inside" GPSDO unit, described as model 57963. No instructions or manual were included with the hardware. The unit has now been powered up for the past 18 hours with the GPS antenna connected with a favorable outside view of the southern sky. I am however uncertain if the hardware is GPS locked based on the two external ACT status LEDs, the leftmost LED is solid yellow and the adjacent right LED is rapidly flashing red. The 1pps LED is flashing once per second as expected. Can anyone point me to an online manual or explain the ACT status LEDs and how to interpret those indications. Tom, there seem to be several types of Chinese GPSDOs, all with green PCB looking end covers, some of which don't even seem to have OCXOs inside, The ones bearing the call sign BG7TBL seem to be quite well made, and do have an OCXO. Those at least will work with Lady Heather and some of the others even seem to have that feature advertised. Try it and see. LH is a marvellous program and with it you can do a precise survey so the Rx knows where it is and so can achieve the maximum accuracy in 2D position hold mode. http://www.ke5fx.com/heather/readme.htm will get you the program and pdf manual. Dan ___ 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] Ref Voltage for GPSDO?
I've been trying to use an Oscilloquartz 8663 in my recently resurrected Shera GPSDO, but the built in V ref of the 8663 has major random instabilities. I've tried another (MTI) ocxo in it's place but that one has galloping ageing problems (the equivalent of 10 to 20 milliHertz per day) and no sign of slowing down after several weeks. Can someone recommend a simple and stable source of around 7 Volts so I can use the (well aged and very stable) 8663? Thanks, Dan ___ 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] Any guesses as to how Citizen is claiming ±1 second/year with using this AT-cut 8.4MHz XTAL?
Way back in 1960 something Braun in Germany made a little alarm clock using a 4.194304 MHz crystal which could reach this level of accuracy. I had one and it certainly met the Harrison level of timekeeping when I used it for navigation. I think that the crystal cut used had a temperature coefficient at room temperatures that had minimal variation at around this frequency. Way better than the 32+ kHz crystals used now. The clock died in the end but I still have the crystal somewhere :^) Dan ___ 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] Cheap jitter measurements
Hi Bob, The performance counter does not use the system time calls, NTP, etc. It's an independent counter clocked from raw CPU clock. So you have a ~300pS Timestamping counter in the processor. Why not use that hardware to do the measurement? Does the signal have to exit the PC to measure it? Yes, getting ~300pS out of the code calls is probably unrealistic for various reasons, however 300nS should be easily achievable. If you use the actual NTP PPS capture code with a few extra lines of code added, you should be able to timestamp PPS and NTP values against the performance counter. David, Correct me if I'm wrong, but the issue with the GetSystemTime calls is they don't use the performance counters. They are system time related calls and affected by UTC/NTP or other system time adjustments. The bigger questions is how does NTP query the serial port? Is it in an actual interrupt routine, or is the data captured via software driven event? (I'm betting on a OS driven event). Maybe the Dave Hart patches improve the PPS capture??? The bottom line is it all depends on now the PPS Capture event is handled, and if that's even predictable enough or stable enough to prove useful. The performance counter is, but getting the PPS code to read the counter is still a software problem. If you guys want to take this offline and chat about it further, I'd be happy to discuss this without using up bandwidth here. Thanks, Dan On 4/10/2018 4:01 PM, time-nuts-requ...@febo.com wrote: Dan, Take a look at Dave Hart's patches to the Microsoft serial port driver, that does something similar. The source may be in the NTP distribution, or Meinberg may have a copy. At one time using the QueryPerfomanceCounter call was an option (look for "QPC"). With Windows-8 and later there is a much more precise GetSystemTime call which NTP uses. I played a little with those calls (in a non-serious way) and wrote some code: http://www.satsignal.eu/ntp/TSCtime.html based on: http://www.lochan.org/2005/keith-cl/useful/win32time.html and just messing around! Perhaps it's of interest or use? Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ 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] Cheap jitter measurements
Hi, Yes, but isn't generating pulses OUT of a PC with low latency/jitter one of the difficult issues? If we (somebody smarter than me...) flip this around and modify a copy NTP to grab the QueryPerformanceCounter value when it gets a PPS pulse and log that count, don't we now have a way to compare the high resolution uncorrected counter to NTP and the external PPS? Agreed, not trivial. But maybe fun anyway! Dan On 4/10/2018 11:03 AM, time-nuts-requ...@febo.com wrote: NTP already looks at incoming pulses and reports what it thinks is going on with them. The desire here is to get a pulse*out* of the device. Then you can toss it into a conventional set of gear. From the data you can independently evaluate what’s going on. So more or less: 1) Generate pulse 2) Work out when the pulse went out 3) Compare that to what NTP thinks is going on 4) Generate a message to describe the delta in time No, not trivial …. Bob ___ 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] Cheap jitter measurements
Hi, Don't know how good they are, but there are two functions in the kernel32 lib in windows that are related to a cpu performance counter, QueryPerformanceCounter and QueryPerformanceFrequency. (Maybe Linux has similar?) Anyway, on most systems the frequency reported is the raw cpu clock. (Couple of Ghz Range numbers, My current system is reporting 3,320,458 Hz, windows7.) Supposedly these are low latency functions. It may not offer a perfect solution, but at least it gives you 'low latency' access to a high speed counter. Maybe it's possible to timestamp incoming PPS pulses with this (assuming they're triggering an interrupt), and learn something neat. Some of this is subject to change with windows versions: https://msdn.microsoft.com/en-us/library/windows/desktop/dn553408(v=vs.85).aspx Dan On 4/10/2018 8:01 AM, time-nuts-requ...@febo.com wrote: kb...@n1k.org said: The kernel clock comes from the CPU clock. That CPU clock is phase locked to a crystal. If you have a CPU that is driven by a VCXO that is a*very* unusual CPU board. The crystal runs at an arbitrary frequency. That gives you edges that are unlikely to happen ���right on the second���. I was assuming the CPU clock was fast enough that reading a cycle-count register and converting to ns would be within a ns which is the resolution of the clock. That's obviously not true for low end SOC type setups. A Pi-1 runs at 700 MHz. The Pi 3 is up to 1.4 GHz. ___ 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] Environmental sensor recommendations.
Hi John, Thermocouples are very robust, and have a very wide operating range. However they require extremely accurate voltage measurements to get to sub degree temperature accuracy. On top of that they require a local temperature sensor to measure the 'reference' temperature (Or an actual Icepoint bath). Once you have those that a lookup table or up to 14th or so order polynomials (Depending on thermocouple, and range) is required to convert the 'reference temperature' and millivolt reading to the temperature measured. Look at some of the NIST copies of the ITS-90 thermocouple tables and coefficients: https://srdata.nist.gov/its90/download/download.html https://srdata.nist.gov/its90/download/allcoeff.tab Overall, a lot of things going on there with errors that all stack up (including silly things like not enough range in floating point number routines for polynomial calculations). Don't get me wrong, they make great sensors. Probably not the right sensor for a small home brew board. IC Temp sensors, thermistors, or RTD's may all be reasonable options here. IC Temp sensors for simplicity, RTD's for accuracy, and thermistors (except where they are in a loop, holding the temp constant) for cost. Dan On 4/5/2018 12:00 PM, time-nuts-requ...@febo.com wrote: Message: 11 Date: Thu, 5 Apr 2018 09:44:48 -0500 From: John Green<wpxs...@gmail.com> To:time-nuts@febo.com Subject: Re: [time-nuts] Environmental sensor recommendations. Message-ID: <cagrb8tlmgxhowoqsgxpg2c2xe8skxnqk1y9_chkmjwmikec...@mail.gmail.com> Content-Type: text/plain; charset="UTF-8" Why has no one mentioned thermocouples? I had some experience with thermistors a few years back designing thermal attenuators and equalizers for CATV. NTC thermistors can have a large change of resistance for a unit change in temperature. They aren't linear, but there are formulas for computing resistance vs temp. PTC thermistors have a much smaller change per unit change in temp., but are much more linear. And, they are susceptible to self heating, which makes things interesting. If I remember correctly, in my research something called an RTD was supposed to be the king when it came to accuracy and repeatability. As someone else has stated, the IC devices are supposed to be quite good, but you have to interface with them. ___ 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] Tracor 527 CRT
On 4/4/2018 2:28 PM, ew via time-nuts wrote: Lat year some one from the UK asked me about a 1 inch CRT for the Tracor 527. I sent David Partridge one at the time, so he is now happy. Dan ___ 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] Identify RFTGM-II-XO Part
Patrick, It's possible that's one of the integrated RF amps, and not just an RF transistor. You should be able to tell by tracing out the circuit. The inputs and outputs will typically be capacitor coupled, with DC fed to the output through a chip inductor or similar choke and resistor. There are some other variations, but that's a pretty common style part. Here's and example. Although I doubt this is exactly what you have. https://www.minicircuits.com/pdfs/ERA-1+.pdf If it's one of these style amp's, you may be able to find a compatible part if you know the rough gain required and frequency of operation. It appears there is a mini circuits part close by, possibly tied into this amp. Can you tell what part of the circuit this board covers? GPS signal, etc? Dan On 1/10/2018 1:26 AM, time-nuts-requ...@febo.com wrote: Message: 3 Date: Tue, 9 Jan 2018 23:33:33 -0600 From: Patrick Murphy<fgdhr...@gmail.com> To:time-nuts@febo.com Subject: [time-nuts] Identify RFTGM-II-XO Part Message-ID:
[time-nuts] A Lady H mystery
I've been trying to get LH (V5) to control and set position for the GPS board in one of my GPSDOs. It is a Trimble "Lassen Ace III" Rx according to itself. LH auto detects it quickly enough, reports it as a TSIP receiver but then shows a screen saying "LOG: OFF", a blank graph grid and nothing much else. No data apparently, so how did it autodetect? I've been beating my head against this for two days; it used to work fine but since a tantalum went on the TTL to RS232 convertor (since replaced along with the receiver itself just in case) it won't perform for me. LH performs fine for all the other units here as it always has and the Trimble Monitor program works on this one. I'd really appreciate someone telling me gently what stupid thing I'm doing or not doing :^) Thanks, Dan - ac6ao ___ 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] UltrAtomic clock.
Hi all, So, anyone notice what time their UltrAtomic clock did the dst change? Mine didn't change last night. Time has been right since it first set itself, so, I'm suspecting it's getting signal. ( We're in northern Michigan, eastern time zone.) Anyone else have a clock that missed dst change? Dan -- Sent from my phone. ___ 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] R XSRM Rubidium Standard
On 9/12/2017 5:58 AM, GandalfG8--- via time-nuts wrote: A friend of mine has bought a just out of calibration R & S XSRM Rubidium standard from one of the so called "recyclers" on Ebay. Nigel / David, Sorry to hear of your "bargain". However I doubt very much that the lamp was made by R themselves, like with the Racal 9475 unit it was probably sourced either as a module or as parts from someone like Efratom and one of those lamps will be found to fit. I'm not in a position to help much at present (just coming out of Chemo). My Racal which was in a similar or worse state when I got that, now comes to life when needed. Cheers, Dan ___ 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] Bad TBolt Crashing LH?
Hi, Not to flood the list with traffic, but as this is probably an issue that many list members run into I'll speak up. FTDI has been very good. We've run everything from their very first chips through USB 3 hardware, and never had any problems. The TTL-232R series of cables are also very handy, USB on one end with 3.3V or 5.0V serial on the other. No dongles... FYI, Mouser and Digikey are also sources: https://www.digikey.com/products/en/cable-assemblies/smart-cables/468?k=FTDI http://www.mouser.com/Wire-Cable/Cable-Assemblies/_/N-bkre6?Keyword=FTDI=True -Dan On 8/30/2017 12:00 PM, time-nuts-requ...@febo.com wrote: Message: 2 Date: Wed, 30 Aug 2017 14:26:24 +0100 From: Dave B <g8kbvd...@googlemail.com> To: time-nuts@febo.com Subject: [time-nuts] [OT] Re: Bad TBolt Crashing LH? Message-ID: <20ce5538-ad60-779f-7a61-a048008bd...@googlemail.com> Content-Type: text/plain; charset=utf-8 Yep, Prolific got badly hit by the counterfeiters. So, they depreciated the use of all the early generation chip-sets (even legit ones!) and had MS push out updated drivers to enforce that. That's why it "appears" to be a Windows update problem that stops many older Prolific based adapters working... The indication of that, is a non working adapter, that shows a Yellow triangle with an exclamation mark, when you look in the Device Manager to see what's recognised. Sadly... FTDI too have been hit by the bad guys out East. They too, had MS push out an update a while back that could detect the fakes and brick them! Well, you can imagine the bad press that created! Thankfully, it is possible to un-brick the things 100% successfully, with a little Googling and a Linux tool. (Rewriting the VID/PID data.) In truth, what seems to have happened is that the counterfeiters are using a micro-controller programmed to emulate the real things, and are getting quite good at it. But.. In the case of the FTDI clones, what should be configurable options (polarity of the serial lines & auxilary IO line functions etc) are fixed, though the FTDI configuration program thinks the chip is good, the requested changes don't take effect, no errors, just no changes. I have also recently purchased "Genuine FTDI" based adapters, only to find that one proudly installed itself with a Prolific driver! The other used the FTDI driver, and both worked, "as standard". But, as I *Needed* the user configurable options, I returned them to the seller for a full refund. Seems he got scammed with 1000's of them! I popped the lid on the one that loaded a Prolific driver, only to find the chip marked up as FTDI! It has to be noted, that it appears that even the very old Prolific chips, and all fakes that I've encountered so far, just seem to be accepted and work as standard, just fine under Linux, but for how long? The only way to guarantee a genuine FTDI adapter, is to buy it from FTDI http://www.ftdichip.com/ They have a webshop, and the prices are not that bad. I use what does appear to be a genuine Prolific based device to talk to my T'Bolt. I used to use that with Windows 7, but I now use Linux Mint (after the great Win10 fiasco) on the same PC. Not a painless change by any means, but I've not regretted it. Regards. Dave B. G8KBV ___ 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] GPS Antenna on Tower.
Hi Bob, So, what sorts of things are done for high precision survey work? I would guess a sturdy mount, good sky view, no reflections, good antenna, no nearby radiators, etc. Those all seem like common sense stuff. But for applications that really matter, what sorts of things might be missing above. Obviously, really expensive silly things won't be done on my site for a few GPSDO's, but it would be good to know what the issues are. Thanks, Dan On 6/16/2017 6:29 PM, time-nuts-requ...@febo.com wrote: Hi Will there be an effect? Yes. Are roughly 99% of all GPSDO’s run with antennas mounted that way by “pros” ? Yes again. If you are setting up a reference site for high precision survey work, don’t do it that way. For a GPSDO, you should be fine. Bob ___ 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] GPS Antenna on Tower.
Hi All, Fair Warning: Nuts Mode Engaged. :) Recently we've moved to a new house and am in the process of getting the antennas back up for various things. One of these is the GPSDO(s), and an obvious location is somewhere on a Roan 25 tower set up just south of the house. At about half way up the tower, there is clear sky view in all directions and the GPS antenna is temporarily parked there about a foot off the tower. The GPS antenna is on the south side of the tower and we're ~47N, so most of the GPS birds should be visible. Single band GPS antenna, nothing special. My guess is this will be fine. However, I'm still wondering what sorts of multi-path or reflections could be expected off the tower itself. And are these enough to worry about? If there is multi-path what sorts of things would help prevent this? (Mounting the antenna further off the tower, etc.) Once I get the tower guy lines redone, I'm thinking about putting the GPS antenna on the tip of the mast (No rotator on this tower). That's at about 75 feet with nothing close by. That would be slightly above the tree line, with a 360 degree sky view. FYI, currently the GPS antenna wire is "Priority Wire and Cable" RG-6/U. Did some measurements last night. It measures as 85 Ohm, with a velocity factor of ~.86. It looks pretty lossy, but it should still work. Any ideas and comments welcome! Thanks, Dan ___ 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] poor-man's oven
The attached plot shows the sort of improvement in warm up time and stability of a simple "oven" made by attaching a Darlington heater transistor and thermistor to a Crystek 100 MHz oscillator, adjusted to set the osc temp to around 35C and wrapping it all in foam. In this application, a DDS clock for an HF transceiver, the result was well worthwhile. Dan - ac6ao Crystek Test.doc Description: MS-Word document ___ 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] Looking for NovAtel GPStation-6
Hello, I am looking to purchase a now-discontinued NovAtel GPS receiver, specifically the GPStation-6 GNSS Ionospheric Scintillation and TEC Monitor (GISTM) Receiver. <https://www.novatel.com/products/scintillation-tec-monitor/gpstation-6/> I have not been able to get a direct response from NovAtel if they might have any remaining units. Any leads for this specific receiver would be appreciated. Thanks, Dan ___ 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] Fwd: HP10811 Oscillator Thermal Fuse
As I reported the last time this subject came up, or maybe the time before, the only time I had an open thermal fuse was in a 10811 that had an open thermistor. I was able to replace that and get the OCXO working, but if the fuse had been replaced with a wire link I'm sure the entire oven would have been toast. There have been two types of fuse fitted, all I those have are the type that can be fitted with the plug in axial panasonic type, less than a dollar from Digikey. The older ovens had a different type but I imagine it's similarly easy to replace. All my 10811s have the higher temperature Panasonic fuse fitted and I sleep well at night... Dan ___ 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] HP 3048A Phase Noise System needs a new home
On 5/1/2017 4:14 PM, Dan Rae wrote: Basic system comprising: 3561A Analyzer 11848A Interface 11729C Carrier Noise Test Set with all extras to 18GHz Basic system is spoken for. Thanks to all and to tvb for being there. Dan ___ 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] HP 3048A Phase Noise System needs a new home
Basic system comprising: 3561A Analyzer 11848A Interface 11729C Carrier Noise Test Set with all extras to 18GHz Bunch of HPIB and Coax cables as needed and pretty much all the paper manuals, several shelf feet. An -hp- 2225A hpib printer which I couldn't get to work in the system as I had it but should work in an RM basic environment. No computer included in this package. I had it working well with an XP machine using the ported program on John Miles' web site and an NI interface card. Optionally: 8662A Signal generator with Opt 003 (Specified Phase Noise for 640 MHz Output). Power supply has been re-capped. 3585A Spectrum Analyzer to extend noise measurements up to 40 MHz from Carrier. A second, spare, 3561A I'm in the LA area in southern California and would prefer pickup. I'm not really up to shipping the whole caboodle... Offers and any questions: DIRECT PLEASE! Dan ac6ao ___ 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] TAPR Oncore M12+ kit
Worth looking closely at these if you've bought one. On mine, apart from the connector to the DB9 being pulled off and some pins bent, which I could fix, there are two tiny SM ceramic caps that have been knocked off the M12 GPS board, both hanging by one of the detached PC traces. This I may be able to fix, but I'm not certain obviously :^) Dan - ac6ao ___ 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] Conversion of Stanford PRS10 to RS-232 Communication
On 4/3/2017 1:05 PM, Philip Jackson wrote: I understand that the PRS10 Rubidium units either talk to the host device via a RS-232 serial command language or via analog values using the same set of pins in both cases. Does anyone know how the format can be changed? The manual doesn't say anything more than there are jumpers inside that can be changed. Page 20 of the manual has the details... Dan ___ 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] Antique precision timing device without, > electronics
This is all cool stuff, and neat to read about. What's the best (Most stable, most accurate, best adev, etc.) tuning fork oscillator made? What the lowest frequency tuning fork oscillator ever built? Was 1Hz ever achieved commercially? Fun stuff for Friday! Dan On 3/17/2017 12:00 PM, time-nuts-requ...@febo.com wrote: Message: 8 Date: Fri, 17 Mar 2017 01:34:39 +0100 (CET) From: "iov...@inwind.it" <iov...@inwind.it> To: Discussion of precise time and frequency measurement <time-nuts@febo.com> Subject: Re: [time-nuts] Antique precision timing device without electronics Message-ID: <1660573894.5853221489710879161.javamail.ht...@webmail-13.iol.local> Content-Type: text/plain;charset="UTF-8" This is mine, used to calibrate some aircraft related equipment: https://www.flickr.com/photos/103726899@N08/33326340242/in/dateposted-public/ and its diagram: https://www.flickr.com/photos/103726899@N08/33482556075/in/dateposted-public/ iov ___ 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] Bye-Bye Crystals
Hi Bob, If one prototypes any crystal oscillator, and runs it on a bench. Then builds an 'oven' of sorts and runs it on the same bench. Would you expect to see any improvement? In other words for a given oscillator (crystal and electronics, etc), will there be any improvements in an oven compared to not in an oven? Or, are there other things that outweigh the gains by temp controlling the whole thing. Yeah, this is a pretty open question, but I don't really have a feel for how good an oscillator needs to be before an oven starts to improve things... Dan On 3/15/2017 12:00 PM, time-nuts-requ...@febo.com wrote: Hi Where do you plan on getting an OCXO grade crystal at an odd frequency like that? Much of the performance of a good OCXO is in the crystal. Doing a proper design on one is a lot of work. You *might* think that having a design for 5.00 MHz would give you a good design for 5.50 MHz. I have empirical evidence that this isn’t the case. Many years later, I’m still utterly amazed that this is the way things work in the crystal business ….( = it’s not just a design issue, it’s also a business decision) More or less the crystal needs to be: 1) Cut specifically to have a turn at a temperature that makes sense for your application. 2) A “large blank” design (for it’s frequency) 3) In a cold weld package (most of the normal crystals are resistance weld) 4) Run through a high vacuum / high temperature process 5) Be plated with gold rather than something like silver or aluminum (unless it’s at VHF). 6) Have a motional capacitance that makes sense for your EFC range ( normally = minimize) 7) Preferably be an SC or modified SC cut. This is for a high stability part. The list does keep going on for a while, but that should give you a pretty good idea. Bob ___ 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] HP5065A Rubidium questions: some progress
On 2/20/2017 4:25 PM, David Scott Coburn wrote: One odd bit is that the resistor in the transistor emitter leg measures about 350 ohms (this is R3 in my schematic). The schematic says it should be 10 ohms. This resistor is on solder posts, so it looks like a 'selected at assembly' item. Corby: it this the 12 ohm resistor you mentioned? Scott, there's no way that oscillator can deliver the power needed to excite the lamp with that high an R3. Something like the specified 10 Ohms is needed. Dan ___ 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] Vintage Frequency Measurement
To put BC-221 things in perspective, the 1 Mc/s reference crystal was adjusted, according to the manual, to within 5 c/s... Things have come a ways since! Dan ___ 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] Vintage Frequency Measurement
On 2/11/2017 10:08 PM, Scott Stobbe wrote: I was inspired recently coming across a Lampkin 105 frequency meter, as to how frequency measurement was done before counters. Certainly zero-beating a dial calibrated oscillator, would be one approach. Google BC-221 and you may get some idea of how those worked. I just wish I could find the one hidden in my garage :^) Dan ___ 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] Autodesk Eagle -- maybe they're listening
Hi, OK, maybe off topic for this list. It'll be my first and last post on this. Spent some time on the phone with autodesk. Something interesting came out of the conversation. The autodesk rep said that he hasn't heard anything but positive feedback about the subscription licensing. (Yeah, Yeah, I know...) He said they have an email address that can be used for feedback. And that if anyone is unhappy, they should let them know what their concerns are. support.ea...@autodesk.com So, please let autodesk know. And foreword this out to other lists and people who can also send out a quick note. Autodesk really needs to hear how we all feel. Thanks! Dan On 1/24/2017 2:06 AM, time-nuts-requ...@febo.com wrote: Message: 3 Date: Mon, 23 Jan 2017 17:24:52 -0600 From: "Graham / KE9H" <ke9h.gra...@gmail.com> To: Discussion of precise time and frequency measurement <time-nuts@febo.com> Subject: Re: [time-nuts] Autodesk Eagle -- maybe they're listening Message-ID: <capyj-ywv70gfreglet694kf+ocebv_rrotrkjcn3lrcv1_q...@mail.gmail.com> Content-Type: text/plain; charset=UTF-8 Hi John: It is still an effective tripling or quadrupling of the cost. I purchased a "non profit" license several years ago for $129. "Non commercial, 4 layers, up to 160 sq cm., all functionality enabled." They converted this to a "standard" license over time. A license was good for the life of a major version, such as 5 or 6. When 7 came out, I had to buy a new license for 7, but it was at the existing customer upgrade price, which was $69. So $129 initially, then $69 every two or three years or so, as new major versions came out. Now they want $100 per year. --- Graham ___ 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] Temperature (environmental) sensors
Hi All, Just ordered a few of these BME280 sensor boards. Also ordered a FTDI C232HM cable to try to SPI or to bit-bang data from the board directly to the PC. If a PIC or similar is required, does anyone on the list have 16Bit PIC code (pic24/dsPIC) C code for reading these BME280 sensors laying around? They really look like a neat little unit. Thanks to all for the heads up on these ones! Dan On 1/4/2017 12:00 PM, time-nuts-requ...@febo.com wrote: Message: 7 Date: Wed, 4 Jan 2017 09:53:24 - From: "David J Taylor" <david-tay...@blueyonder.co.uk> To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Subject: Re: [time-nuts] Temperature (environmental) sensors Message-ID: <076CCA551DC142C2A8D93CF02A4AD1A3@Alta> Content-Type: text/plain; format=flowed; charset="UTF-8"; reply-type=original I like the Bosch BME280 conneced to a Raspberry PI. https://learn.adafruit.com/adafruit-bme280-humidity-barometric-pressure-temperature-sensor-breakout/pinouts https://github.com/adafruit/Adafruit_Python_BME280/blob/master/README.md -- Björn Some performance plots are here, with some comparison between the pressure readings from various sensors. http://www.satsignal.eu/mrtg/performance_air_temp.php This is on mixed Windows/Linux platforms. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk Twitter: @gm8arv ___ 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] Why is holdover LED on HP 58503A not lit, when GPS lock is unlit too?
On 12/18/2016 9:34 AM, Dr. David Kirkby (Kirkby Microwave Ltd) wrote: *12 -- ---MODE Survey: 0% complete If it's still showing that after being on for five hours, maybe it needs to be explicitly told to start a survey? dr ___ 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] Switching regulator replacement for 7805
Depending on the application, another possible application is to sync up the DC/DC converter to the "main" clock source. This makes the switching noise then coherent to the system, which either makes it average out completely, or possible to filter it out in the digital domain using a deep notch-filter in receiver applications. You are assuming the switching noise is directly caused by the fundamental switching frequency, this may not always be the case. Often the fast edges can excite parasitic reactances in the board and components, which in turn oscillate and radiate at their own frequency. This is not necessarily related to the switching frequency. That said, it may be an interesting test to run anyway! Dan ___ 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] Switching regulator replacement for 7805
On 12/5/2016 12:00 PM, time-nuts-requ...@febo.com wrote: This is exactly the PWM to PFM mode switch I described earlier. The 850mA are probably high enough that the DC/DC converter works in PWM mode, thus switching with a constant frequency, even if the load changes. On the other hand 200mA of a 1A converter is low enough that it's most likely in the PFM region, where every small change (or noise) causes the switching frequency to change. I would guess at 200mA the switcher is still operating PWM. With that tiny little inductor, the inductor has probably fallen into discontinuous current mode. Usually this is bad for noise generation. It would be interesting to see what a scope trace of the switched leg of the inductor looks like in both cases. Dan ___ 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] hp 5065A
On 10/29/2016 9:42 AM, John Ponsonby wrote: Gentlemen, I am interested in getting an old hp 5065A Rubidium frequency standard working again. I recall that if one of these units is left not running for a long time that the rubidium atoms get adsorbed onto the glass of the cell and filter. John, the procedure for that is on page 3-1 and 2 of the manual, but it may not be necessary. Lots has been published about these and I'm sure a Google search will turn them up, in particular there's an Italian authored pdf from, I think, a member of this group. There are some electrolytic caps that will need to be checked and replaced where necessary. Having said that mine came back to life after being in dusty storage for about ten years and all it needed was a good clean... Dan ___ 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] Opening an Isotemp OCXO
On 10/28/2016 9:09 AM, Peter Reilley wrote: The only document that I could find said 12 volt. Pete. The 82 series came in a lot of flavors. I have one 82-49 which is definitely 12V ( draws 0.12A when warm and maybe 0.3 when cold) and has a 5V pp square wave output at 10 MHz. It also has a Vref output and an EFC input. What is odd about this one is that it came to me from a TRW swap meet scrap dealer who bought stuff from Cubic Communications in San Diego and it had a "Reject" tag from them. Probably because it was supposed to be a 5 MHz unit as marked, so presumably had the wrong crystal fitted by Isotemp. Other versions of the 82 series (-10) were fitted to Racal Receivers like the RA6790/GM. Screw adjustment on the side and 5 MHz output. Are you sure yours shouldn't have a 5V supply on that output IC? Could be why it died if there is an internal regulator that failed putting the full supply voltage on the IC? Dan ___ 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] Temperature/Humidity
Simple, build your room (8 x 12), use a water sealing paint paint, install a split mini cooling unit at approx.8,000 BTU, set temperature below oven temperature of the equipment.Carefully choose AC size (not to big). Door at far end of room. ___ 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] 1PPS to 32.768 khz
Hi, = If you want to go Tom's picDIV route, and are lazy like me, this is one of several boards available. https://oshpark.com/shared_projects/kXG6K5Xu You'll get several copies of the bard board for under $10. Few minutes stuffing it, and you'll have a working device... Dan Hi Lee, It's not likely you can directly multiply 1PPS up to 32 kHz, but it's easy to divide 10 MHz down to 32 kHz. See http://leapsecond.com/pic/src/pd30.asm for a $1 PIC example. A stand-alone 10 MHz OCXO or the simplest possible GPSDO would work for your digital clock project. Chris and Nick and many others have shared low-cost Arduino-class examples to the list over the years. Another example is the MCU-less James Miller design which uses a PLL at 10 kHz. Contact me off-list some day when want a Trimble Thunderbolt; they are still available. /tvb ___ 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] TNS-BUF High Isolation, Low Noise Buffer Amp Available
For those of us who aren't scared of surface mount stuff, and maybe even prefer it, will there be any bare boards available? Dan - ac6ao ___ 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] Thunderbolt spurs on 10MHz output at 100Hz and 200Hz from signal.
On 9/21/2016 9:01 AM, David C. Partridge wrote: Yes, I fear a timepod is a bit out of my budget (I can dream tho'). Over here in the UK PN measurement kit is a bit thin on the ground too. So I looked at <http://www.wenzel.com/documents/measuringphasenoise.htm> but that seemed a little thin on details. Or were you referring to something else? The Wenzel note is at: http://www.wenzel.com/documents/circuits1.htm as a pdf under link: "Low noise amplifier for Phase Noise measurements" or try: www.wenzel.com/wp-content/uploads/lowamp.pdf Pretty much all there, but the FET is hard to find now. Dan ___ 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] Thunderbolt spurs on 10MHz output at 100Hz and 200Hz from signal.
On 9/21/2016 8:01 AM, David C. Partridge wrote: Looks like all I've managed to do is measure the baseline noise of the analyser. Ho-hum looks like I need something a *lot* quieter to do these measurements. Indeed Dave, yes. I made the same mistake a few years ago when I tried to compare the results of three different DDS clocks on the output of my homebrew transceiver DDS LO using a 3585A spectrum analyser and John's program. It took me a while to figure out why they were identical and then the penny dropped that I was just measuring the 3585A... The plot of the three thunderbolts I sent before using my -hp- phase noise system is interesting in that the white plot was from the Tbolt I keep on the bench to run all the stuff there, and it uses the switch mode power supply that came with the TAPR ones, built into an Extron distribution amp case. All the spurs that are shown with dotted lines aren't all spurious, most are probably real. The other two are from units with linear supplies and are significantly improved. Most older phase noise systems use some kind of low noise oscillator for reference, mixing the signal under test down to AF and going from there with low noise amps and then the actual measurement. Wenzel has a very good application note describing a system that can be copied in the home lab. I attach a plot of my -hp- 3048A system noise floor showing what levels can be achieved with twenty year old technology. The spurs the system shows dotted may not be real. The modern system John Miles designed can no doubt do better and in about one hundredth of the volume, but is a little more expensive :^) Dan ___ 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] Normal operating specs of a Morion MV89?
These have been discussed before at some length. It is not just the output cap that is easily damaged by rough salvage efforts, which however are sadly common enough. There is also a frequently seen problem of bad output spectra with a lot of non harmonic related stuff in the output, not a problem I felt capable of or interested in tracking down. In my sample of two from China via eBay, one was good the other not. Dan ___ 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] Thunderbolt spurs on 10MHz output at 100Hz and 200Hz from signal.
On 9/18/2016 5:42 AM, David C. Partridge wrote: I've just redone the measurement without the external attenuator and with 10dB attenuation set internally to the analyser. The results are attached. I suspect that you are measuring the analyser phase noise, but it's rather early in the morning... I attach, if I can get it to work, a plot of three different Tbolts on my 3048A system. Dan ___ 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] time-nuts Digest, Vol 146, Issue 13
This may help. http://www.auberins.com/index.php?main_page=index=1 Look at: SYL-1512A (Or any of the others, really...) If you want to lock a temp down and use a light bulb or similar, this is a pretty cheap way to go. I've used them for large soldering irons, reptile incubators, and temp chambers. They work great if you need to hold temp long to stabilize everything before a measurement. Very nice units for the price. I'm sure you know this, but watch your temp gradients in the chamber. Dan As we all know, step #1 in making a clock is NOT to build a thermometer:-) I thought I would check the brain trust here to see if anyone has seen a hobbyist grade temperature testing chamber or kit or homebrew design. I have some crystals, oscillators, and other electronics I would like to characterize over temperature. I know this reflector has discussed homebrew stabilization ovens; however, they have tended to have very long time constants (which makes sense for that application). I need to be able to change temperature in a reasonable amount of time, and I don't need extreme stability. Looking for any ideas, maybe in the "maker" spirit. I think the size I need would be perhaps 1/2 the size of a shoebox. BTW, in case someone has a chamber to sell, let me know... Rick Karlquist N6RK ___ 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] Q/noise of Earth as an oscillator
On 7/27/2016 10:04 AM, time-nuts-requ...@febo.com wrote: Exciting the Earth with a new frequency (and an adeguate amount of energy) sets a new rotational speed: you cannot retune a (for example) quartz crystal in the same way... Sure you can. Spin it at 100 RPM, or 1000, RPM or even 25000 RPM... :) Interesting conversation. I tend to agree the earth is not a classic harmonic oscillator. Energy is not exchanged between different storage mechanisms. It's rotational period has no natural harmonic frequency. i.e. rotational period could be anything. However I also agree it exhibits characteristics of other items that Q can be calculated for. Rate of slowing, loss of energy per cycle, etc. And since the definition of Q is varied and used quite widely, it seems Q is also appropriate here. Maybe Earth is a special case since after all it DID give us the second, and we DO set our atomic clocks to IT every 6 to 12 months... ...now I'll be thinking of this all night... ...I think Tom is just toying with us now... Dan ___ 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] 5061B Service Manual, Page 8-57 (BEAM I, if LOW)
On 7/16/2016 8:11 PM, Christopher Hoover wrote: My 5061B (with FTS tube) has a low beam current. Maybe 7 on the meter when adjusted onto the primary peak. I bought the Ops and Service manual, but my copy is missing page 8-57 (and 8-56 if that exists). Christopher, Given that Foldout Page 8-57 (Beam I LOW Troubleshooting Chart) is Fig 8-30 and Fig 8-29 (The HIGH version) is Page 8-55, I don't think there actually is a Page 8-56. Since my computer was forcibly updated to WIN10 my scanner no longer works with it but if you don't get a better offer I will try to get an old laptop to work with it tomorrow and scan Fig 8-30. It's too hard to abstract what you need, and will have to be in segments anyway. Dan ac6ao ___ 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] There is a Tracor 527E on ebay
On 7/15/2016 4:19 AM, Bert Kehren via time-nuts wrote: Have been using mine for over 15 years, very handy tool and using the > 1 MHz output for very high resolution measurements. Bert Kehren If anyone is in need, I have both a 572E as well as a 572A (the version with a 1" CRT display, a new tube fitted in this case) that I rarely use and I would be open to offers. As to the eBay one shown with a UK power plug, I'm pretty certain that the power transformer in these can be wired or switched for 110 / 220 V but my manual eludes me... Dan ___ 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] Visiting Greenwich
Dave, it's been a few years since I was there but the Harrison clocks are not in the main part of the museum but in the Observatory which is a bit to the South and East if I remember right. Both are well worth a look, but the Harrisons are magic of course. Dan ___ 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] frequency generation algorithm.
Hi, Quick question to the group, maybe slightly of topic. I'm looking for a quick and dirty algorithm or method to generate a pulse train at arbitrary frequencies based on a fixed clock source. This will be run as code in a timer ISR in a microcontroller, so some calculations can be done. Ideally the division ratio could be changed, say from 100% to 0% of the master frequency. Frequency resolution is not highly critical, however it would be very nice to have a 'dithered' answer for odd ratios. Ideally the pulses in the pulse train would be as evenly space as possible. Any ideas, search terms, code examples are all welcome! Thanks! Dan ___ 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] How to properly characterize 32kHz oscillators manually and with a microcontroller?
On 6/27/2016 1:51 PM, Hal Murray wrote: I assume you are doing this for fun. That means you get to do whatever you think will be fun. The DS3231 is pretty crappy by time nuts standards. Maybe, but simply by adjusting mine by measuring the 32 kHz output with an accurate counter I can get them to keep to within about one second a month. I have two incorporated in homebrew HF transceivers that I built and find that their performance is actually pretty impressive, /for what they are/. Being able to set time zones and UTC offset from the radio's front panel is also handy. After all they only claim to be a fairly accurate clock. I doubt that any of the fancy schemes being proposed for measurement will improve the basic accuracy much. Dan ___ 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] OT stuffing boards: was GPS interface/prototyping
I’ve been doing SMT assembly for 40 years. I have never ever seen anybody with a process that “just worked”. They all involve some amount of fine tuning and design optimization. Hi, Yep, The amount of tweaking required to get a good board build can be extensive. Part density, ground plane, part sizes, solder type, solder age, stencil design, board finish, and SMT pad design all add up. Tweaks in the oven and stencil can be required to make it work. It's the tweaking it that can get expensive fast... Dan ___ 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] HF frequency counting receiver
On 6/20/2016 11:18 AM, Mark Spencer wrote: I am quite convinced that HF Doppler shift is a real issue at times. Absolutely true Mark. I spent some time looking at this way back when and it is quite possible to observe (in Southern Calfornia) transitory phase shifts on the 10 MHz signal from WWV of more than 360 degrees. Some times of day are worse than others. In 2003, the last time I bothered with the FMT and then it was from a signal at the ARRL, i.e. right across the country from me, I was able to get within 0.1Hz using nothing more than a 1Hz tuning receiver with external reference and a 100 kHz IF output which I compared with another output from the Standard on an oscilloscope. But this did involve a lot of visual averaging and estimation on the 'scope as the apparent received frequency varied. This was the usual method of measuring frequencies off air in the day. Most more "modern" FMT approaches have been using sound cards, but I've no experience of these. Whatever method is used once you have any ionospheric reflections then you will start to see phase shifts which will be what limits your accuracy. Dan ac6ao ___ 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] ADCs for phase noise measurement
The 2378-20 is a pretty nice ADC. I expect the 2368-24 to be good also. It should be easy to see at least -130dBfs noise floor with an FFT. Keep in mind supply rail noise, and REF voltage noise etc. That's a lot of resolution and bandwidth in one unit! The DC890B board appears to run an FTDI FT245BM. I wouldn't expect that to be able to transfer data at the full rate from the ADC to the PC. So you'll be limited to the buffer size on board (memory or FPGA buffer) for snapshots of data. That may not matter for what you'd be doing... Dan On 6/12/2016 12:00 PM, time-nuts-requ...@febo.com wrote: Alternatively, I would suggest using one of the modern sigma-delta >or SAR ADCs, which can deliver increadibly high ENOB and SNR at >astonishing sampling rates. Good candidates might be: > >AD7982, 18bit 1Msps >AD7984, 18bit 1.33Msps >LTC2378-20, 20bit 1Msps >LTC2368-24, 24bit 1Msps > >Eval boards for these are available (between 100 and 200€) and interface >with SPI. You can either use an USB SPI dongle (between 5 and 50€) or >use a small uC board to interface with the PC. Saving the samples in >a wav file and using one of the many FFT tools shouldn't be a problem. > Good call on the LTC2368-24. The eval board for it has considerably better support (like p-scope) than do the Analog Devices eval boards. I think this might work for me. What are the tradeoffs between SAR and sigma-delta ADC? Can you point me to a few of the "many" FFT tools? Maybe I don't have to buy spectrum analyzer software. Thanks. Rick ___ 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] Goodie for British Timenuts!!!
On 6/7/2016 10:38 AM, cdel...@juno.com wrote: RACAL MA259 FREQUENCY STANDARD FROM 1965 Looks neat Corby, Internally they're a rebadged Sulzer more or less. There's been one for sale on eBay in the US for years, literally, at the somewhat ridiculous price of over $3,000. item: 252399450511 only now slightly reduced! One might wonder what state the 21 NiCads are in after all those years :^) And I couldn't sell my Sulzer for $50 at the swap meet, and that had new NiCads. They are remarkably stable if my Sulzer is anything to go by, and it has a lovely mechanical fine frequency adjustment behind that multi turn dial. ___ 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] HP 106a oscillator connectors question
Corby wrote: Need help identifying the RF connectors on the unit. Corby, I may have some connectors on leads but would have to dig deep in my garage. They were used a lot on some UK made Racal receivers in the sixties... Let me know if you still need them. Dan ___ 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] picDIV board.
So, having a batch of PIC12F675's to play with the picDIV's with, but being lazy I decided to look for a dev board for the 8 pin PIC's. (Yeah, I know how lazy can you get! :) ) Just didn't feel like wiring up the programming header to a bread board, etc. Anyway, one appeared in google on OSH park and Tindie. Looks like the same guy. So for anyone thinking about playing with the picDIV but feeling as lazy as I am, this might be a good option. It even includes some prototype area on the board! From OSH park you get 3 boards for under $10. https://oshpark.com/shared_projects/kXG6K5Xu For those of you who don't know what a PIC DIV is: http://www.leapsecond.com/pic/picdiv.htm My guess is it would also work with a picPET and an FTDI cable. http://www.leapsecond.com/pic/picpet.htm Dan ___ 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] Looking for Z3801 Power Supply Board
On 5/23/2016 3:54 PM, Dave M wrote: Dan, If you haven't already found the Z3801A page at http://www.realhamradio.com/GPS_Frequency_Standard.htm, you should read it thoroughly (in your case, especialy the section on the power supply). there is a good pictorial that shows locations of all the power supply test points. Using that pictorial, you should be able to determine which power supply is causing the problem (there are several). Dave, it's completely dead. I do have a schematic of the board (of uncertain origin), but I suspect it is one of the DC/DC convertors that is dead. It just puts the power supply I'm feeding it from into tick mode but I can't find any obvious short anywhere. It could be a Tantalum inside one of the aforesaid convertors, but it's not blown any pico fuses. I will continue to puzzle over it... Dan ___ 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] Looking for Z3801 Power Supply Board
My Z3801 power supply board has given up the ghost. It had been working well apart from an occasional Error 230 causing it to go into Holdover for no good reason from time to time which may well be related of course. Does anyone have a good power supply from an otherwise dead unit which might enable me to get it going again? I've had the darn thing for fifteen years and miss it :^) Dan ___ 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] GENIUS by Stephen Hawking (PBS TV), with 5071A cesium clocks
I have a recording of this on my hard drive, at1.3 Gb it's too big to email but I can share it via Wetransfer if anyone wants it. I would need a recipient's email address to do this. Dan ___ 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] High rate, high precision/accuracy time interval, counter methods
Hi, I've looked at the higher end TDC from ACAM. They claim a 40Mhz data rate, with burst of 200Mhz max. However it wasn't clear what the maximum sustained rate would really be. Answers became a little obscure when pressed for maximum sustained data rates. Overall the chips weren't horribly expensive considering what you get. http://www.acam.de/products/time-to-digital-converters/tdc-gpx/ Do keep us posed if you come up with something that works at 20Mhz or 30Mhz rate. I still have a possible application for something like that. Dan On 5/3/2016 12:00 PM, time-nuts-requ...@febo.com wrote: Message: 16 Date: Tue, 3 May 2016 14:31:17 +0200 From: Attila Kinali<att...@kinali.ch> To: Discussion of precise time and frequency measurement <time-nuts@febo.com> Subject: [time-nuts] High rate, high precision/accuracy time interval counter methods Message-ID:<20160503143117.3d9c9144e22fc3b5305f4...@kinali.ch> Content-Type: text/plain; charset=US-ASCII Hi, We had here a discussion about measuring events (ie time stamping them precisely) with high rates. As some of you know, Javier and his group, Bruce and me are working on a system that should give us something better than 10ps (my guess is that we should get close to 1ps) at a rate of (guestimated) 1MHz per channel. (Based on the excitation of a LC tank and measuring the ring-down/phase with an ADC). As it is with researches, we want the moon, and prossible even more. So we were talking about getting the measurement rate up even higher, to 10MHz and if possible 50MHz with the same precision. The above approche will not work above 1MHz. Using different filters it might be possible to get it up to maybe 10MHz, but it would be an awkward design at best. The only methods I am aware of (and could find) that achieve such high rates are those, based on (vernier) delay lines (and their equivalent ring oscillator ones) in ASICs. But this means that a costly ASIC needs to be produced. Does someone know of other methods that could achieve high measurements rates with better than 10ps precision/accuracy? (This question is mostly a hypothetical question out of interest, I don't plan to build one...yet:-) Attila Kinali ___ 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] RG6 or LMR400 for GPS Antenna (Symmetricom, 58532Aand T-bolt)
On 4/22/2016 12:00 PM, time-nuts-requ...@febo.com wrote: On 4/21/16 6:03 PM, Tom Van Baak wrote: >Paul, > >If possible can you make an audio recording of a woodpecker attack? You know it's a form of 1pPS. >I'd like to add that data set to my list of ADEV plots. > I am sure, like almost all oscillators, it will have 1/f flicker noise. It's not unheard of around here to increase shot noise to solve the problem... Dan (I'm done now, I promise!) ___ 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] Rpair of an 8662 HP Generator
On 4/15/2016 3:38 PM, John Miles wrote: Have a look at the capacitors in the voltage divider that drives the bases of the switching transistors. There's a good chance that's your problem, and they probably need to be replaced even if not. 75-TVA1607 (Mouser p/n for Sprague TVA1607) works well. John for what it's worth both my 8662 and 8663 which are late (1994) revisions have these single 15 µF caps replaced by two parallel 10 µFs among other changes in the power supply area. Maybe worth doing if they can be fitted... Dan ___ 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] How to run Lady Heather under Windows10
Hi, Sorry, I have to speak up here. This fake stuff isn't "clone" FTDI hardware. It is counterfeit hardware. And it uses FTDI's VID illegally. FTDI should block counterfeit hardware from using their drivers. Making the assumption that the counterfeit junk will work, and putting blame on FTDI for blocking it is unacceptable. Unfortunately, some of us trying to save a few bucks are ripped off by vendors selling this garbage. FTDI chip makes great hardware. Real FTDI hardware and drivers make an amazingly easy to use USB solution. They are extremely reliable. Dan On 3/18/2016 12:00 PM, time-nuts-requ...@febo.com wrote: -- Another issue is that FTDI is back at it again with making their drivers incompatible with clone FTDI chips. Their previous attempt actually bricked the clone USB interface chips. Their latest driver just sends garbage out the serial port. If you are using a cheap USB to serial converter cable there is a very good chance it has a clone chip in it and FTDI's latest driver may be up to its evil ways. ___ 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] MTI 260-0624-D OCXO
For anyone interested to know an induction heater, If you happen to have one laying around, works pretty well for opening these types of cans up. Properly placed you can heat the can melt the solder and not burn up any paper labels on the top of the can. If done carefully, they can be reassembled this way also. My guess is even the cheap inductive cook tops would work for this. Dan I have read sometime ago and probably on this list a success stories about opening OCXOs using a hot air gun or even a propane torch, an x-acto knife and a stainless steel shim sheet to avoid the solder to do it stuff again when solidifying. Using this technique probably the can could be reused after repairing the part. Ignacio EB4APL ___ 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] Trimble Thunderbolt error
I saved my LH screen just as the period of seeing no satellites ended with one coming into view at the bottom, and again maybe an hour and a half later. In between LH reported "No Almanac" at some point. Whatever was being done must have been fairly major! Dan ___ 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] Seeking HP 3561A schematic diagrams
On 2/12/2016 11:28 AM, Charles Steinmetz wrote: I'm helping a colleague resurrect a hard-luck HP 3048A phase noise measurement system. In particular, he asked me to help get the 3561A dynamic signal analyzer working again. I downloaded Volume 1 of the service manual from Keysight, which contains Sections I through VI but does not contain Section VII (schematics and service information). I suspect that Section VII is Volume 2 of the manual, but do not know for sure. Vol 2 does indeed contain all the schematics and is about 2 inches thick with a lot of oversized fold outs, it will not be an easy one to scan... There is also an operating manual. Have you asked Dave at Artek, he might have one in the pending pile? (I'm not sure if there are any hardware differences between "regular" 3561As and the ones supplied as part of the 3048A system. I'm pretty sure the faults [at least the major ones] lie in the basic hardware, so I don't think we need schematics particular to the 3048A if there are differences.) The 3048 system uses a standard (working!) 3561A. There are no differences. I don't think the optional extra memory is required either. Dan ___ 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] MicroPulse L1/L2 Surveying Antenna
Does anyone have any details on the above antenna? Part Number is: 90LL122300-2 and it has a sticker on it saying it is a Global Hawk Asset, it has a big set of choke rings (about 35 cm across) and looks as though it might have been designed to be mounted flush on an aircraft body. I'm doing a LH survey at present with it perched temporarily on a wall at the back of my house and it seems healthy at 5V supply. Dan ac6ao ___ 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] PRS10 C900 replacement
Hi, You need one more piece of info: its value! E.g. 1uf, 0.35uF, 2.2uF, 10uF? That is quite important :) Just don't use too old tantalum caps - they tend to absorb moisture over time (when stored incorrectly) - and self destruct as you have experienced.. I just experienced the same while renovating a Tek 475 'scope. Regards Dan (A newbie from Denmark) -Oprindelig meddelelse- From: davidh Sent: Tuesday, January 19, 2016 11:21 PM To: time-nuts@febo.com Subject: [time-nuts] PRS10 C900 replacement Hi All, While still appearing to function normally, my PRS10 started to smell: C900 in the lamp assembly has self destructed. The SRS parts manual merely says "Capacitor, Tantalum, 35V, 20%, Rad", so I'd appreciate any advice on what additional parameters I should be looking at in selecting a replacement. Thanks, david ___ 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] Phase Noise Comparisons
On 1/16/2016 5:00 PM, KA2WEU--- via time-nuts wrote: Did my plot make it ? Ulrich It did. Very impressive! Dan ___ 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] PPS phase between two GPS units.
Hi all, Thanks for all the responses. The GPS units were swapped on the splitter ports, and the phase difference did in fact change. It changed from 21nS to around 5nS. Not exactly what was expected, although it would tend to indicate the RF path is not the same through the splitter. Last night a 'symmetrical splitter' was made up using a mini circuits ZFRSC-42. Both of the outputs to the GPS units were AC coupled. A bias T was inserted directly on the antenna feed with external power feeding the new splitter antenna port. The PPS's are now very close, about 1 nS average difference. If this holds solid, in a few days I'll swap splitter ports again. Thanks, Dan ___ 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] PPS phase between two GPS units.
Hi All, So I've been playing with some timing hardware here, and have noticed something rather curious. I have two otherwise identical Lea-6T GPS modules, configured exactly the same. These units are tied to the same antenna, with a splitter with the same length cables running to each unit. They were given the same survey coordinates. Initially there was not any appreciable difference between the PPS outputs. The outputs were on average within about one nS of each other. However after a day or two they started to display a difference of about 21nS between the PPS outputs. This is also evident in the GPSDO output, as the phase of the 10Mhz is also skewed by 21nS or so. A few days ago I started a 48 hour survey. The came up virtually identical coordinates at the end of that survey. After the survey the phase is still 21nS different. At this point, my only thought is the GPS splitter. It's DC coupled to one unit, and AC coupled to the other. It is possible there are some delays on one output vs. the other due to the blocking caps and bypass inductor in the splitter. I've tried swapping the GPSDO units on the splitter, so we'll see what happens there. Can anyone offer any insight as to why the two units may have a different PPS output timing? It's not really a problem, more of a curiosity and mildly academic exercise. Thanks, Dan ___ 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] HP 5065A battery pack
On 11/21/2015 6:13 AM, Bob Camp wrote: Hi The key issue is that there has been a lot learned about charging batteries since the 5065A was designed. Just as other parts of the 5065 can be improved with some work, so can the battery charger. Given that NiCad’s aren’t cheap, it’s worth noting that the circuit could be worked on *before* somebody buys a bunch of batteries to re-cell one. Moving a bit further off topic and back to our original conversation when you re-did yours (2 years ago?) - you don’t get a lot of standby time even with the full load of NiCads in there. Bob, I stopped writing dates on the chart thing inside the pull down cover in August 2004 since the numbers had not changed significantly since 2002 (and still haven't) which in fact must have been when I did the battery. Time flies... A bit more than my guess of 5 years! It got a check recently when we had an outage that lasted for a good twenty minutes and the green light stayed lit. -hp- spec is for more than ten minutes. And incidentally the schematic shows the battery as 25.2 Volts which might indicate 21 cells, although I'm sure it would work with 20 and maybe there have been early versions that did have 20; mine is late, the last but one serial prefix. It's certainly possible that the circuit might be improved but it does seem to perform as advertised as is. For extended periods than there is always the DC input as has been pointed out. I suspect this option was more for moving the thing from one lab to another adjacent rather that flying clock trips or mountain climbing :^) Dan ___ 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] HP 5065A battery pack
On 11/20/2015 10:52 AM, cdel...@juno.com wrote: Any one know how many cells went into the HP 5065A battery packs? 21 Corby, in three rows of seven, from my notes when I re-celled mine. Dan ___ 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] HP 5065A battery pack
On 11/20/2015 4:54 PM, Bob Camp wrote: Hi I don’t in any way doubt your count. If indeed they are putting 21 cells into that circuit, the NiCads likely don’t last as long as they might with a different charging circuit …. Bob Bob, I was answering Corby's query; mine had an original -hp- battery pack which I assumed was designed by someone who knew what they were doing, so I just put new Chinese made 2.2 Ah Nicad cells in it, exactly the same number as the original, however I don't know the capacity of the originals, they were unmarked. Five or six years later it still will hold the thing up for at least twenty minutes, which I would think is what matters. It would in any case be difficult to fit any more than 21 in the space available. Dan ___ 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] 10811 unsoldered fuse
On 10/19/2015 11:51 PM, Richard (Rick) Karlquist wrote: The thermal fuse plugs into pin sockets. It cannot be soldered for the obvious reason that the solder would melt it...at 109 degrees as it is marked. My suggestion would be to jumper it out of the circuit. However, if you'd rather have some small degree of protection against meltdown due to the thermistor failing open, a good replacement which fits is available for less than $1 from Digikey: EYP-1BF115. This was discussed about a year ago at some length. Dan ___ 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] time-nuts Digest, Vol 134, Issue 23
Hi Bob, I have a similar oscillator tied to a GPSDO that another list member is developing. I have not seen the EFC turn around! That's seems very unusual. If you are interested, I may be able to give you a plot of my EFC over the last ~3000 hours. Pretty boring decay curve, with the oscillator sitting at around 3e-12 per day drift. (The oscillator was on for about 6 months prior to being hooked to the GPSDO...) Dan On 9/23/2015 3:10 AM, time-nuts-requ...@febo.com wrote: Date: Tue, 22 Sep 2015 23:49:25 -0400 From: "Bob Benward"<rbenw...@verizon.net> Continuing this discussion, I have included a PDF showing the past 30days of EFC. Amazingly, the drift has reversed direction! Anyone have any insights into this behavior? Each data point represents 10 seconds. Bob ___ 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] HP 3048A Alternative to HP3561A?
On 9/4/2015 8:07 PM, John Allen wrote: Hello all - I have always wanted an HP 3048A system. I have acquired a 11848A, but need an HP 3561A or equivalent. Is there any substitute to the 3561A? John the problem is that all the software is specific to the 3561A so unless you are going to write your own version, you're stuck with the instruments that the 3048 software will address. One exception is the Voltmeter, the later meters like the 34401A will work with the hpib commands for the 3478A. Also, are their other spectrum analyzers that are acceptable other than the ones listed here? The same applies to spectrum analyzers for the HF segment. There are 3561As around, after a lot of searching I found not one but two, however both needed some work to get them running perfectly. Personally I have had much more trouble getting the computer part of the system to work than I had with the hardware, and I still have not managed to generate my own calibration files... John Miles has some excellent pages on his site concerning the 3048A. Dan ___ 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] KS-24361 EFC Error
On 8/12/2015 4:13 AM, Bob Camp wrote: Hi Indeed, there is a *lot* of difference between the REF-1 and the REF-0. Working out a clone of the two could be a major undertaking. I’d only try it if there was nothing else on my schedule for the winter :) It’s the observation that the ROM’s are likely identical that has me interested in the idea. *IF* that’s a correct guess (and I have not verified it’s true with dumps), there must be jumpers that tell the board what it is and what it does. There *could* be some interesting things that you can do with this or that jumper. Bob, some of the differences are on the bottom of the board and appear to be concerned with the interface connector. Also of course the stuff to supply power to the antenna. The interface stuff might be deciding where the 1 pps comes from? I took a long look at the two boards side by side and decided that there was way too much to move from one to the other and vice versa, and not all of it easy to identify either. All the ICs with paper labels are similarly marked in both the -0 and -1 units. Much as I like a challenge, this is a few dozen parts too far for me... Dan ___ 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] KS-24361 EFC Error
On 8/11/2015 4:09 PM, Bob Camp wrote: For the very ambitious, start swapping ROM’s and GPS parts from the “dead” REF-1 over to the “live” REF-0. For what it's worth, I have a dead Ref-1 here that came to me with a dead power supply; that is now fixed but there seem to be other problems as well. I looked at swapping over the gps parts from that to a new Ref-0 and very rapidly came to the conclusion that it was not a possibility, there's an awful lot of stuff different between the two units, especially underneath, maybe fifty components in total, although it does look as though the ROMs are the same, at least they have the same part numbers. Dan ___ 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] HP10811 dual oven
Hi, If you search the internet, you should come across a design by Warren S. It's basically the same type of oven controller that is used in the internal oven for that oscillator. I did a surface mount version of his design a while back. I've been running it for quite a while now. IMO it is helping to reduce the thermal drift of the oscillator. Bob has pointed out in the past that the outer oven was not intended to be active all of the time. This is probably true. That said it seems to help in my setup. If you are unable to find the documentation, please let me know. I can try to dig it up when I get home. Dan On 8/3/2015 12:00 PM, time-nuts-requ...@febo.com wrote: Hi The “external” heater on the Z3801 OCXO is only needed if you are regularly running below -20C in your environment. Other than the alarm signal, there is no harm in letting it simply shut off forever. Bob On Aug 2, 2015, at 8:56 AM,tim...@timeok.it wrote: Hi, I have seen, but I do not remember where, someone have rebuilt the external oven controller to complete a stand alone OCXO removed from an HPZ3801A. Can you hep me to find the document? Luciano timeok ___ 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] Flashback to 1988 (Austron Catalog)
Sure. I uploaded a scan of the catalog parts to KO4BB. It's listed in Recent Uploads awaiting sorting. As for the 2100F manual, is there a scan available online already? Dan On Sun, Jul 26, 2015 at 2:03 AM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: In message cac2_fprrd0hpwbrqbejvwsiuaq8afrmn1be25wtdqnh+pxy...@mail.gmail.com , Dan Watson writes: The serial-numbered original manual was also included. Inside the plastic wrapping was an Austron catalog from 1988, complete with vintage smell! It is very interesting to look through. Attached is a picture of the spread for you Austron fans. Can we persuade you to all that stuff and uploade it to KO4BB or similar ? I'd love to get a chance to read it... -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Any other useful purpose for Austron 2100F or SRS FS700 receivers in US
On 7/11/2015 8:14 AM, James Robbins wrote: Does anyone know of any other genuinely useful purpose to which the Austron 2100F, SRS FS700, etc receivers can be put in the US since the demise of Loran? Inquiring minds would like to know. Jim Robbins, N1JR Jim, I gave my Austron to a friend in the UK, at the time shipping wasn't as bad as it is now, so I hope he was reasonably happy. I can't see any real hope of it ever coming back here, although there have been frequent reports of eLoran testing, I'm not sure they ever amounted to anything. Dan - ac6ao ___ 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] Reeeely long term HP 5065A drift rate (13 year!)
On 6/30/2015 10:21 AM, cdel...@juno.com wrote: Yes, same workbench and location! How about some of the 5065A owners helping out in a bigger sample? What I thought is that say on July the 4th a few owners measure their frequency offset to say at least 5X10-12th and then without changing the C-field for a year we could repeat the measurement next year and see what kind of results we get. Corby, by some quirk of fate I have a 5065A here that has been operating continuously (apart from the odd power outage of longer than the batteries could supply) since 2002. My problem is that I'm not sure how to get to the degree of accuracy that you ask. I set it originally using a really old method, feeding 5MHz from it and another input from a GPS standard into a DB mixer and plotting the output on a pen recorder, getting down to better than one cycle error per 24 hours. A quick check today on a 2465B 'scope shows an absolutely static trace at the highest timebase speed. What measurement method would you recommend, absent a working Caesium standard and a Timepod? I have a 5370B somewhere, but nothing more modern. Dan ___ 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] Help with my ADEV measurement setup
Oddly enough I do have a PPS output from the TCXO I was measuring. It's on a little board I made and there is a PicDiv right on it. I'll have to play around with that. I did notice the aliasing issue trying to measure a 12MHz crystal. It appeared to have incredible stability and accuracy for a plain old XO... Also it has a frequency offset of over 1kHz, and I noticed that I had to manually type in the correct initial frequency during setup to have meaningful data in the frequency difference view. i.e, 12001053 instead of 12E6. But of course with a marginally stably oscillator, that poses a problem. How long do I wait to find a mean frequency to type in...? It makes total sense why this is so in TI mode, but still it's one more thing to deal with. I think I'll stick with frequency mode for most things. Many of the oscillators I want to measure are right around 10^-8 or 10^-9, and I'd hate to constantly be fighting the noise floor of the instrument. I'll treat the data from frequency mode as relative and that should get me what I need. At least until I own a better instrument. Thanks Dan On Tue, Jun 30, 2015 at 10:49 PM, John Miles j...@miles.io wrote: Yep, it will ignore any non-numeric data like us suffixes. It will always interpret incoming data as seconds, so the 1E-6 scale factor is appropriate if the counter is returning microseconds. I'll tweak the mouseover help text for the scale factor field to clarify that. I think you're basically getting valid data. The 53131A's one-shot resolution is 0.5 ns, and you're seeing about 2E-9 residual ADEV at t=1s. It's in the right ballpark, anyway... e.g., on a 20-ps HP 5370, the residual ADEV at t=1s will usually be in the neighborhood of 30-60 ps. I would, however, be worried about aliasing with a TCXO. If its frequency is more than 5E-8 off -- meaning it drifts more than 50 nanoseconds per second with 10 MHz at the STOP jack -- its error will end up underrepresented in the measurement. In this case your oscillator is drifting quite a bit (as expected) -- look at the 'w' view of the original phase compared to the unwrapped 'p' phase. You could try putting 1pps on both the START and STOP jacks but that'll require more futzing with scale factors, 1pps dividers and the like, and may leave you more vulnerable to trigger uncertainty from various causes. For measurement of a TCXO, I'd stick with frequency mode. The ADEV plots won't be 100% kosher but they'll be fine for relative comparisons with other plots from the same measurement setup. -- john, KE5FX Miles Design LLC -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dan Watson Sent: Tuesday, June 30, 2015 5:05 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Help with my ADEV measurement setup I tried both the PPS and the 10MHz signal on channel 1, with the 10MHz DUT on channel 2. Tom emailed me and it turns out the software was not detecting the units correctly from the serial string. (What are 6 powers of ten between friends, right? :) ) Likely a settings mistake on my part, I sent him a screen cap to see what's up. None the less, I manually enter the time units and was able to plot some data. I attached a new screen cap. How does this look? Thanks Dan On Tue, Jun 30, 2015 at 5:36 PM, Bob Camp kb...@n1k.org wrote: Hi Are you using a PPS as the “start” and the 10 MHz as the “stop” or comparing two PPS signals? Bob On Jun 30, 2015, at 2:47 PM, Dan Watson watsondani...@gmail.com wrote: Hi, I'm trying to take some ADEV measurements with my 53131A, and I'm having some issues. This is my setup: - 53131A with the OCXO option. Calibrated against a T-bolt. I also did the TI Quik cal and it passed - I'm using RS-232 out with a null modem cable into a Serial-USB converter - Software is TimeLab in talk-only mode. 53131A check box is checked. - The counter is in TI mode, with a T-bolt on Channel 1 and DUT on Channel 2 - A delay of 1 second is set on the counter. TimeLab seems to accurately detect this interval I started measuring various devices, and could never seem to get better than around 1x10^-6. Even my Rb was showing a 1 second ADEV of 10^-6. Finally I put the T-bolt on channel 1 with common mode on to both channels, and it still measures around 10^-6. A picture of that is attached. Surely this can't be right. I tried frequency mode and it gives ADEVs of 10^-12 on the Rb and T-bolt, as expected. I understand the issues with filtering that the 53131A does internally on this mode, but at least it shows my setup is working to some degree. It's TI mode that seems to be wonky. I'm probably doing something really stupid. Thanks for any help you all can suggest. Regards, Dan W
Re: [time-nuts] Help with my ADEV measurement setup
I tried both the PPS and the 10MHz signal on channel 1, with the 10MHz DUT on channel 2. Tom emailed me and it turns out the software was not detecting the units correctly from the serial string. (What are 6 powers of ten between friends, right? :) ) Likely a settings mistake on my part, I sent him a screen cap to see what's up. None the less, I manually enter the time units and was able to plot some data. I attached a new screen cap. How does this look? Thanks Dan On Tue, Jun 30, 2015 at 5:36 PM, Bob Camp kb...@n1k.org wrote: Hi Are you using a PPS as the “start” and the 10 MHz as the “stop” or comparing two PPS signals? Bob On Jun 30, 2015, at 2:47 PM, Dan Watson watsondani...@gmail.com wrote: Hi, I'm trying to take some ADEV measurements with my 53131A, and I'm having some issues. This is my setup: - 53131A with the OCXO option. Calibrated against a T-bolt. I also did the TI Quik cal and it passed - I'm using RS-232 out with a null modem cable into a Serial-USB converter - Software is TimeLab in talk-only mode. 53131A check box is checked. - The counter is in TI mode, with a T-bolt on Channel 1 and DUT on Channel 2 - A delay of 1 second is set on the counter. TimeLab seems to accurately detect this interval I started measuring various devices, and could never seem to get better than around 1x10^-6. Even my Rb was showing a 1 second ADEV of 10^-6. Finally I put the T-bolt on channel 1 with common mode on to both channels, and it still measures around 10^-6. A picture of that is attached. Surely this can't be right. I tried frequency mode and it gives ADEVs of 10^-12 on the Rb and T-bolt, as expected. I understand the issues with filtering that the 53131A does internally on this mode, but at least it shows my setup is working to some degree. It's TI mode that seems to be wonky. I'm probably doing something really stupid. Thanks for any help you all can suggest. Regards, Dan W adevtest.png___ 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.
Re: [time-nuts] Help with my ADEV measurement setup
Attached is a screenshot of the setup window. I manually typed in 1E-6 as the units. I also hit Monitor and let it average the reporting interval for a while until it settled at 1.00 seconds. Originally I was leaving the time unit as 1, and microseconds in in the serial string was not being detected to set the units automatically. I'd be happy to send you a tim file as well if necessary. Let me know. Thanks Dan On Tue, Jun 30, 2015 at 8:51 PM, John Miles j...@miles.io wrote: Let's see a snapshot of your acquisition dialog, just before you hit 'Start'. (Or send me a .tim file directly.) It can be tricky to configure the test setup for a TI measurement, since so many more things can go wrong compared to a frequency-based setup. -- john, KE5FX Miles Design LLC -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dan Watson Sent: Tuesday, June 30, 2015 11:48 AM To: time-nuts@febo.com Subject: [time-nuts] Help with my ADEV measurement setup Hi, I'm trying to take some ADEV measurements with my 53131A, and I'm having some issues. This is my setup... ___ 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] Help with my ADEV measurement setup
Hi, I'm trying to take some ADEV measurements with my 53131A, and I'm having some issues. This is my setup: - 53131A with the OCXO option. Calibrated against a T-bolt. I also did the TI Quik cal and it passed - I'm using RS-232 out with a null modem cable into a Serial-USB converter - Software is TimeLab in talk-only mode. 53131A check box is checked. - The counter is in TI mode, with a T-bolt on Channel 1 and DUT on Channel 2 - A delay of 1 second is set on the counter. TimeLab seems to accurately detect this interval I started measuring various devices, and could never seem to get better than around 1x10^-6. Even my Rb was showing a 1 second ADEV of 10^-6. Finally I put the T-bolt on channel 1 with common mode on to both channels, and it still measures around 10^-6. A picture of that is attached. Surely this can't be right. I tried frequency mode and it gives ADEVs of 10^-12 on the Rb and T-bolt, as expected. I understand the issues with filtering that the 53131A does internally on this mode, but at least it shows my setup is working to some degree. It's TI mode that seems to be wonky. I'm probably doing something really stupid. Thanks for any help you all can suggest. Regards, Dan W ___ 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] Testers needed: Arduino (Thunderbolt) TSIP Library
Hello, I'm in the final stages of developing a new TSIP communications library for Arduino devices. What distinguishes this library from the others that I found and mulled over, is an ability to configure and handle the TSIP packets that arrive asynchronously via 232 serial I/O from a Thunderbolt. The library is being developed on UNO R3, Nano, Mega and DUE platforms (it should work on others) and supports both UART-based, and software (bit-banged) serial ports. On systems (like DUE) it can use 8-byte precision floating point. Setup and use is straight-forward requiring only a handful of code lines to get started. Thus I am looking for a few volunteers with the hardware, time and desire to help test and validate the utility of the library before I release it to the community wild. If you are interested please let me know off-list. Best, Dan Quigley (N7HQ) Note: The libraries are derived from the great work by Mark Sims, John Miles and Tom Van Baak. Please note this is not a complete Lady Heather-like implementation, but the structure and base functionality is there to advance it to that point. I also have a more complete library implemented in C# if anyone is interested. ___ 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] Performance of 74LVC series ICs
Thanks for all of the replies, very useful. Also for the recommendations on the 74LVC1G74 and 1G80. I don't know why I didn't check for a 7474 in this technology, of course they would have that available. But it looks like the 1G80 will do just exactly what I need in a smaller package, so I think I'll go with that. Dan On Tue, Jun 9, 2015 at 8:52 AM, Dan Kemppainen d...@irtelemetrics.com wrote: Hi Dan, 74LVC1G80. See: http://www.ti.com/lit/ds/symlink/sn74lvc1g80.pdf Might be worth looking at. Dan On 6/9/2015 4:24 AM, time-nuts-requ...@febo.com wrote: Let's say I have a 20MHz TCXO. I want to square up the output signal and divide by two. Easy, just a buffer or inverter and a flip flop. But looking at the pinout of the 74LVC1G175 (D flip flop) it doesn't have a Q not output. So now I need a second inverter to make it toggle. The 74LVC2G14 includes two schmitt inverters in the package, but will isolation inside the device be good enough to use it for two separate functions at 20 and 10 MHz? ___ 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] Performance of 74LVC series ICs
Hi Dan, 74LVC1G80. See: http://www.ti.com/lit/ds/symlink/sn74lvc1g80.pdf Might be worth looking at. Dan On 6/9/2015 4:24 AM, time-nuts-requ...@febo.com wrote: Let's say I have a 20MHz TCXO. I want to square up the output signal and divide by two. Easy, just a buffer or inverter and a flip flop. But looking at the pinout of the 74LVC1G175 (D flip flop) it doesn't have a Q not output. So now I need a second inverter to make it toggle. The 74LVC2G14 includes two schmitt inverters in the package, but will isolation inside the device be good enough to use it for two separate functions at 20 and 10 MHz? ___ 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] Performance of 74LVC series ICs
I have something of a follow up question. How good is the isolation inside these devices (74LVC, SOT-23 package) between gates? Let's say I have a 20MHz TCXO. I want to square up the output signal and divide by two. Easy, just a buffer or inverter and a flip flop. But looking at the pinout of the 74LVC1G175 (D flip flop) it doesn't have a Q not output. So now I need a second inverter to make it toggle. The 74LVC2G14 includes two schmitt inverters in the package, but will isolation inside the device be good enough to use it for two separate functions at 20 and 10 MHz? Just from a layout perspective using three devices instead of two would be easier. However the thing will be battery powered, so I'd like to save the power if possible. Thanks Dan On Mon, Jun 1, 2015 at 6:13 PM, Andy ai.egrps...@gmail.com wrote: The gates on that page http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/trangate.html use bipolar transistors. The 74LVC parts are CMOS. There are various effects caused by that difference. And those examples have vastly inferior control over input switching levels, compared to just about any well made digital IC from the last half century. (Funny to think that it has been half of a century!) 2N type transistors might have switching delays upwards of 100 ns (depending on load), whereas the LVC parts switch in the 1-5 ns range. On the other hand: A well designed discrete circuit can beat a general purpose integrated circuit in almost all performance measures. Some performance metrics would be hard to beat with even a well designed discrete circuit. On-die capacitance and inductance tends to be much smaller than any discrete circuit can achieve. Andy ___ 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.
