Re: [time-nuts] 10.23 MHz SC cut 10811 compatible crystals available
Rick, On 11/15/2010 06:25 AM, Richard (Rick) Karlquist wrote: Someone was asking about SC cut crystals to play with. I have a few dozen 10.23 MHz SC cut crystals that are interchangeable with 10811 10 MHz crystals, except for the frequency difference. They were made for a GPS version of the 10811 that never saw the light of day. Any interest in these? Vigorous hand-waving. Yes. Cheers, Magnus ___ 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] ADEV
10 MHz locked LNBs do not use a separate connector. Everything goes down/up the single main coax. The typical L-band down-converted frequency and the 10 MHz are easily separated, as is the DC. These are definitely not inexpensive. Regards - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-901-9193 cell -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of jimlux Sent: Sunday, November 14, 2010 11:49 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] ADEV David I. Emery wrote: 3. External reference LNBs with 10 MHz (pretty universal) going up the cable that also carries power and brings the L band signal down. I'm not entirely sure how many of these designs simply bandpass filter and then limit the 10 MHz and use that directly as a PLL reference and how many phase lock a VCXO to the 10 MHz coming in. Otherwise similar (and often derived from designs for) the internal reference PLL types in 2 above. And, I'll bet those are fairly pricey.. (after all, it needs another connector, and that's a price sensitive application..) ___ 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 does one actually do Allan variation graphs?
Hi The only reason the check list is any good is the - gee if I'd checked that I would not have bought this one syndrome ... The same socketed ROMs on the A that have issues while they are live are easier to replace if / when they go bad. --- Many of these counters (any model) spent their life on an external standard. Having an OCXO that's a ppm or two off is not unusual. What you want to watch out for is the one that's 30 or 40 ppm off. Bob On Nov 14, 2010, at 11:15 PM, John Miles wrote: Bob's checklist is a good one, all right. It is important to get a solid working example because they are quite challenging to troubleshoot and calibrate. The only problem with the 5370A as far as I'm aware is the reduced reliability caused by the larger number of socketed ROM chips. It seems that many, if not most, 5370s were used with external 10 MHz references. If you're patient, you can wait for one to show up on eBay with a display that is blank except for one bright LED. Buy it cheap, and flip the external-reference switch back to internal-reference mode when you get it. Easy fix! -- john, KE5FX -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]on Behalf Of paul swed Sent: Sunday, November 14, 2010 8:01 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] How does one actually do Allan variation graphs? Really good advice on what to checkout. 5370s are the devil to fix if somethings wrong such as jitter. Good luck. Paul On Sun, Nov 14, 2010 at 12:40 PM, Bob Camp li...@rtty.us wrote: Hi Like a lot of stuff, the going price for these has dropped. They get less and less respect every day ... One thing that may be specific to me - I do not consider a 5370A to be any more or less valuable than a 5370B. They both do pretty much the same thing. The 5370B might have fewer hours on it, it might not. On average 5370A prices seem to run slightly higher than 5370B prices. Why is a mystery to me. Bob On Nov 14, 2010, at 11:57 AM, William H. Fite wrote: Thanks, Bob He's asking $400 but I can tell by the look in his eye that he'll take substantially less. He's a lousy poker player, too... I asked him to turn it on about 0900 this morning and I'm going over in an hour or so to check it out. Thanks again, Bill On Sun, Nov 14, 2010 at 11:44 AM, Bob Camp li...@rtty.us wrote: Hi Assuming: 1) All the knobs and switches are intact and working 2) All the led's in the display work 3) All the alarm and indicator LED's work 4) The input amps are good 5) All the connectors are intact 6) The OCXO is good / on frequency 7) It passes the diags 8) Jitter is down below 100 ps ( should be below 40) 9) You can check all this out before purchace. Let the beast warm up for at least an hour before you check it. Something in the $180 to $260 range is probably fair depending on cosmetics. You might start out at $150 in order to compromise at $200. I certainly would not pay over $300. I know the list sounds a bit long, but I've seen 5370's with problems in each of those areas. Pretty much anything damaged / non-functional would knock a pretty good chunk off the price. Bob On Nov 14, 2010, at 11:29 AM, William H. Fite wrote: Gentlemen, What is a reasonable price for a 5370A? Local guy here is trying to hawk one to me. Not cosmetically perfect but fully operational. Yes, I know someone is going to say, I got one for 50 bucks. But really, what is a fair price? Thanks, Bill On Sun, Nov 14, 2010 at 10:48 AM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 11/14/2010 09:41 AM, John Miles wrote: I’ve looked at Wikipedia and I am as lost as when I started. Could someone walk me through the process step by step and also tell me what test equipment is required? Besides the pointers at www.leapsecond.com , I've collected a few links at http://www.ke5fx.com/stability.htm that may be helpful. The first .PDF link on that page is my presentation from the Microwave Update conference a few weeks ago. It was meant as an introductory Stability Measurement for Radio Nuts talk, discussing the state of the commercial art in light of what's available to hobbyists. The NIST links under General timing and noise metrology, in particular this one ( http://tf.nist.gov/general/pdf/2220.pdf ) are excellent. If you have an HP 5370A/B counter and a GPIB interface you can do a lot of good measurement work. With the appropriate software you can make conventional strip-chart style plots of frequency and phase, as well as ADEV and similar plots. Unless you are a software nut you probably do not want to homebrew the necessary code to do this. Most people don't use the same program for acquisition and plotting; a script or batch file does the job of
[time-nuts] Getting Started in High Precision Timing
Hello all, I have been a software hacker for years but have never really done too much hardware hacking. I have been looking at oxco modules, but the data sheets of various vendors do not really provide me with a good basis as to what such an oscillator would provide me. I assume its just oscillation given the given frequency. Do any of you all have any good links/resources aside from what a basic google would provide, as to how to get the data from the oscillator at a pulse-per-second rate allowing me to do some basic timing. Really, I'm just looking for some first steps in hacking on these high-precision oscillators. Thanks -Matt ___ 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] 10.23 MHz SC cut 10811 compatible crystals available
At 11:25 PM 11/14/2010, Richard (Rick) Karlquist wrote: Someone was asking about SC cut crystals to play with. I have a few dozen 10.23 MHz SC cut crystals that are interchangeable with 10811 10 MHz crystals, except for the frequency difference. They were made for a GPS version of the 10811 that never saw the light of day. Any interest in these? Yep. ___ 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] microwave radio cameras Re: ADEV
Rex wrote: On 11/14/2010 7:24 PM, David I. Emery wrote: 3. External reference LNBs with 10 MHz (pretty universal) going up the cable that also carries power and brings the L band signal down. I'm not entirely sure how many of these designs simply bandpass filter and then limit the 10 MHz and use that directly as a PLL reference and how many phase lock a VCXO to the 10 MHz coming in. Otherwise similar (and often derived from designs for) the internal reference PLL types in 2 above. These ER types are more apt to be used for more exotic specialized applications where very high frequency accuracy or some degree of phase coherence with other equipment or LNBs is useful. Obviously with the high multiplication factor, one needs a quiet reference inside the PLL bandwidth (and that is pretty wide to ensure reliable lock) - one suspects that issues with degradation due to mechanically induced noise and phase shift in the cables can be a problem. I picked up an LNB a about 10 years back that used this external reference method. The LO in the thing was a DRO that locked to a 10 MHz signal coming up the cable. The LO in this one locked to 10.750 GHz. Experimenting, I found that the DRO adjustment screw could be turned and it would lock every 10 MHz. I found it would lock as low as 10.690. I assume it would tune up about that far too. I needed an LO in the 10 GHz area, so I hacked mine to use it just as a LO, not using any of the receive chain. Here's a page where I described the LNB and what I did with it. http://www.xertech.net/Projects/sat_lo.html Maybe the description there will help someone. If nothing else, it show pictures of what one external ref type LNB looks like. Interesting.. NORSAT makes lots of those sort of devices for VSAT (Very Small Aperture Terminal) applications (e.g. satellite internet).. I've seen a few of them at work being used in that kind of application. Those would make life easier for my scheme. They're not quite so common as the LNB for Ku-band TV (at least I've not seen them at Best Buy/Radio Shack kinds of places), nor have I seen them on neighbors houses or out at the curb on trash day. But I'm starting to think the pilot tone technique might be easier... At first glance, if one considers two alternatives: LO locked to reference, down converting RF to baseband and digitizing and LO not locked, but with in-band pilot tone, down converting RF to baseband and digitizing, then essentially mixing with the downconverted pilot tone should produce comparable results. In the first, you're controlling the LO (at least inside the loop bandwidth), and in the second, you're really measuring it, then taking out its changes. Assuming that the pilot tone amplitude is small enough that it doesn't cause nonlinearity problems in the LNB, and that it's in band, it should be comparable. But, maybe there's a SNR of the reference issue? In a PLL, you're comparing a very strong signal to a very strong reference, so the noise floor of both is very small, while in the pilot tone, the reference is strong, but not as strong, relative to the noise flor. ___ 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] ext ref LNB Re: ADEV
Mike Feher wrote: 10 MHz locked LNBs do not use a separate connector. Everything goes down/up the single main coax. The typical L-band down-converted frequency and the 10 MHz are easily separated, as is the DC. These are definitely not inexpensive. Regards - Mike Ah.. but the question is really not whether the new price is cheap, but whether there's some reason why someone would be doing a massive refit, and dumping lots of these on the market surplus. ___ 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] ext ref LNB Re: ADEV
Well, that I do not know. The majority of Ku Ka LNBs for home TV use are using free running DRO's. I have a bunch of them, and never ran across any locked ones, except for some of the ones used for internet service. My real experience is what we use in military satcom terminals at Ku and Ka bands, with apertures from 0.6 to 9.2 meters, and they are all locked to an external 10 MHz reference. I doubt if you will see any major dumping of those. Especially now, because of strict ITAR. Even if one can buy it directly from the manufacturer, once the military has owned it, they will probably dispose of it in such a way that we will not see them on ebay. Regards - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-901-9193 cell -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of jimlux Sent: Monday, November 15, 2010 9:21 AM To: Discussion of precise time and frequency measurement Subject: [time-nuts] ext ref LNB Re: ADEV Mike Feher wrote: 10 MHz locked LNBs do not use a separate connector. Everything goes down/up the single main coax. The typical L-band down-converted frequency and the 10 MHz are easily separated, as is the DC. These are definitely not inexpensive. Regards - Mike Ah.. but the question is really not whether the new price is cheap, but whether there's some reason why someone would be doing a massive refit, and dumping lots of these on the market surplus. ___ 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] 10.23 MHz SC cut 10811 compatible crystals available
Someone was asking about SC cut crystals to play with. I have a few dozen 10.23 MHz SC cut crystals that are interchangeable with 10811 10 MHz crystals, except for the frequency difference. They were made for a GPS version of the 10811 that never saw the light of day. Any interest in these? Absolutely! JDB. [still working on that DIY GPSDO design] -- LART. 250 MIPS under one Watt. Free hardware design files. http://www.lartmaker.nl/ ___ 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] ext ref LNB Re: ADEV
Mike Feher wrote: Well, that I do not know. The majority of Ku Ka LNBs for home TV use are using free running DRO's. I have a bunch of them, and never ran across any locked ones, except for some of the ones used for internet service. My real experience is what we use in military satcom terminals at Ku and Ka bands, with apertures from 0.6 to 9.2 meters, and they are all locked to an external 10 MHz reference. I doubt if you will see any major dumping of those. Especially now, because of strict ITAR. Even if one can buy it directly from the manufacturer, once the military has owned it, they will probably dispose of it in such a way that we will not see them on ebay. Regards - Mike I doubt the LNB is export controlled.. It's unlikely to have an exotically low noise temperature, they're not cryogenic, they don't use components with dual-use, it's just part of a receiver. If you go to the NORSAT website, for instance, they don't make much mention of export controls (yeah, I'm sure the invoice/quote would have export boilerplate on it the contents of this have not been reviewed... use, sale, distribution may require license...) http://www.norsat.com/lnb/blog And I note that the datasheet's pretty sketchy on the external reference LNBs.. They give phase noise as follows (for Ku band, 10.75 GHz LO): -75dBc/Hz @ 1kHz -85 @ 10k -95 @ 100k But they don't say whether that's added to the reference noise, or that's the outside the loop noise, or what.. What's interesting is that the Ka-band LNB (for 18-19 GHz, which is low Ka, to my thinking.. I think 30 when I think Ka).. the noise is actually lower -65 @ 1k -75 @ 10k -95 @ 100k -100 @ 1M ___ 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] ext ref LNB Re: ADEV
The military Ka band is 20.2 to 21.2 on receive and 30 to 31 on transmit. Norsat of course has been making these for about 15 years, one of the first. Back when I was working on Milstar 25 years ago, with the same receive frequency, even the NF was classified. No, it does not make sense, but, that was the way it was. I just had to deal with some ITAR related issues, where, COTS equipment is being used, yet, it is now built for, or owned by the military, and, while the hardware is not classified, it is restricted, even as to who may work on it. I am just saying, do not hold your breath to see them coming on the military surplus market. Regards- Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-901-9193 cell -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of jimlux Sent: Monday, November 15, 2010 10:16 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] ext ref LNB Re: ADEV Mike Feher wrote: Well, that I do not know. The majority of Ku Ka LNBs for home TV use are using free running DRO's. I have a bunch of them, and never ran across any locked ones, except for some of the ones used for internet service. My real experience is what we use in military satcom terminals at Ku and Ka bands, with apertures from 0.6 to 9.2 meters, and they are all locked to an external 10 MHz reference. I doubt if you will see any major dumping of those. Especially now, because of strict ITAR. Even if one can buy it directly from the manufacturer, once the military has owned it, they will probably dispose of it in such a way that we will not see them on ebay. Regards - Mike I doubt the LNB is export controlled.. It's unlikely to have an exotically low noise temperature, they're not cryogenic, they don't use components with dual-use, it's just part of a receiver. If you go to the NORSAT website, for instance, they don't make much mention of export controls (yeah, I'm sure the invoice/quote would have export boilerplate on it the contents of this have not been reviewed... use, sale, distribution may require license...) http://www.norsat.com/lnb/blog And I note that the datasheet's pretty sketchy on the external reference LNBs.. They give phase noise as follows (for Ku band, 10.75 GHz LO): -75dBc/Hz @ 1kHz -85 @ 10k -95 @ 100k But they don't say whether that's added to the reference noise, or that's the outside the loop noise, or what.. What's interesting is that the Ka-band LNB (for 18-19 GHz, which is low Ka, to my thinking.. I think 30 when I think Ka).. the noise is actually lower -65 @ 1k -75 @ 10k -95 @ 100k -100 @ 1M ___ 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] 10.23 MHz SC cut 10811 compatible crystals available
Rick-- Sign me up for one. I'll even save you the postage! Bob K6RTM (down the street) -- Message: 2 Date: Sun, 14 Nov 2010 21:25:59 -0800 From: Richard (Rick) Karlquist rich...@karlquist.com Subject: [time-nuts] 10.23 MHz SC cut 10811 compatible crystals available To: Discussion of precise time and frequency measurement time-nuts@febo.com Message-ID: 4ce0c467.4020...@karlquist.com Content-Type: text/plain; charset=ISO-8859-1; format=flowed Someone was asking about SC cut crystals to play with. I have a few dozen 10.23 MHz SC cut crystals that are interchangeable with 10811 10 MHz crystals, except for the frequency difference. They were made for a GPS version of the 10811 that never saw the light of day. Any interest in these? 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] 5 and 10 MHz crystal filters
On 11/15/2010 7:44 AM, John Ackermann N8UR wrote: I'd like to find a couple of 5.0 and/or 10.0 MHz crystal filters, preferably configured for use in-line with 50 ohm coax. I've done some googling but don't find anyone selling these as a stock item. Do they exist? Any pointers would be appreciated. Used/surplus is fine (even preferable). John, You don't say what width you require or any other details other than it should be 50 Ohm, but these are relatively easy to build in a ladder configuration with stock crystals. Google produces a lot of hits for crystal ladder filters; the first: http://www.aade.com/filter32/dishal.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] Getting Started in High Precision Timing
I have been a software hacker for years but have never really done too much hardware hacking. I have been looking at oxco modules, but the data sheets of various vendors do not really provide me with a good basis as to what such an oscillator would provide me. I assume its just oscillation given the given frequency. Do any of you all have any good links/resources aside from what a basic google would provide, as to how to get the data from the oscillator at a pulse-per-second rate allowing me to do some basic timing. Really, I'm just looking for some first steps in hacking on these high-precision oscillators. Matt, Yes I'm sure many on this list have large collections information but you would need to be very specific to receive an answer, make, model, and which spec. Several projects can be found in the list archives for dividing the oxco rate to the PPS rate. Check the TAPR web site for a TADD-2 PPS divider. In general you accumulate all sorts of lab grade test equipment or make your own equipment to measure the output. The catch 22 is you need a better reference to measure a unknown device. Most start with GPSDO and a Time Interval Counter / Frequency Counter a way to log your data to process on a computer is good unless you want to go old school with pen and paper and stop watch ;-) Stanley ___ 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] 5 and 10 MHz crystal filters
Hi John I have a collection of filters but I have not seen any common ones at those frequencies with 50 ohm termination. The characteristic would probably require transformer input and output coupling, the inherent impedance of most filers in this frequency range will be around 1kohm. The narrower the lower the impedance. Those crystal frequencies are available relatively cheaply it should be possible to make a ladder filter with some form of matching to 50 ohms quite simply. There are lots of references around (the recent QEX has on on overtone crystals, but does reference some of the articles on fundamental crystal filters.) Alan G3NYK - Original Message - From: John Ackermann N8UR j...@febo.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Monday, November 15, 2010 3:44 PM Subject: [time-nuts] 5 and 10 MHz crystal filters I'd like to find a couple of 5.0 and/or 10.0 MHz crystal filters, preferably configured for use in-line with 50 ohm coax. I've done some googling but don't find anyone selling these as a stock item. Do they exist? Any pointers would be appreciated. Used/surplus is fine (even preferable). Thanks! John ___ 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] Temperature sensors and bridge amps
And more important... they do not consume power continuously ;) Regards, Javier El 15/11/2010 20:18, Alan Melia escribió: Maybe the same things Harry ?? The advantage of latching relays is that they maintain the position (EFC) if you lose the command link. You cant hear the clicks in Space :-)) Alan G3NYK - Original Message - From: Harry Brownharryhbr...@earthlink.net To:rich...@karlquist.com; Discussion of precise time and frequency measurementtime-nuts@febo.com Sent: Monday, November 15, 2010 7:00 PM Subject: Re: [time-nuts] Temperature sensors and bridge amps Back in the early 80's I was working for a company making military communication satellites. The 5 MHz Oscillators used on the satellite were in a double oven keeping the oven temp within 0.001 Hz C. We could adjust the oscillator frequency for aging by ground commanding a bank of relays controlled a D/A converter to adjust the oscillator frequency. Lots of fun back then. Any idea what is used now? 73, Harry, W3IIT - Original Message - From: Richard Karlquistrich...@karlquist.com To:time-nuts@febo.com Sent: Saturday, November 13, 2010 10:48 AM Subject: Re: [time-nuts] Temperature sensors and bridge amps The HP E9183A achieved 1 millidegree over -55 to +85C in a single oven. The time lag was dealt with by adding a double integrator to PID. Rick Karlquist N6RK On Fri 12/11/10 8:26 AM , Bill Hawkins wrote: in the heater control loop. Of course, you can't get to a millidegree from ambient with just one oven. And you can't eliminate time lags if you have any thermal mass. ___ 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. -- Javier HerreroEMAIL: jherr...@hvsistemas.com Chief Technology Officer HV Sistemas S.L. PHONE: +34 949 336 806 Los Charcones, 17 FAX: +34 949 336 792 19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.com ___ 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] D/M picture
Looks very nice Bert On Sat, Nov 13, 2010 at 3:26 PM, ewkeh...@aol.com wrote: ___ 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] 5 and 10 MHz crystal filters
A friendly warning about crystal filters. Crystals, whether used in an oscillator or filter, have intrinsic phase noise. You cannot improve the phase noise of a crystal oscillator with a crystal filter unless the filter crystals have lower phase noise than the oscillator crystals. In general, post filtering of an oscillator is rarely done for the reasons I mentioned. One place where it made sense was in the HP 8662 with the 640 MHz output option where a 10811 is multiplied to 80 MHz and then filtered to reduce the noise floor. It is further multiplied to 640 MHz and filtered again by a SAW filter, that was made at HP in those days. As others have mentioned, filter characteristic impedance is a function of the crystal physics. There is a specific impedance that you must use for a given bandwidth. Fortunately, it is easy to put transformers at the ports to convert to 50 ohms. Rick Karlquist N6RK On 11/15/2010 7:44 AM, John Ackermann N8UR wrote: I'd like to find a couple of 5.0 and/or 10.0 MHz crystal filters, preferably configured for use in-line with 50 ohm coax. I've done some googling but don't find anyone selling these as a stock item. Do they exist? Any pointers would be appreciated. Used/surplus is fine (even preferable). Thanks! John ___ 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] 5 and 10 MHz crystal filters
Rick - Unless I misunderstood, I do not believe what you said is correct. A crystal filter can indeed improve the far out phase noise of a crystal oscillator. The oscillator's noise is not only a function of the crystal, but, the combination of the crystal noise and the amplifier noise used for feedback and the Q of that circuit. All of those additional components degrade crystal noise. Consequently, a 100 Hz wide filter at 10 MHz can really do a nice job on just a decent 10 MHz oscillator. Lincoln Labs proved this in their EDM of a satcom system in the early 80's that then I took over in industry to replicate and improve in 1986. We did have a 10 MHz crystal filter in there for cleanup. In our application, the final transmit frequency was close to 45 GHz, and it needed to be very clean, even after an optimal architecture used to get us up there. 73 - Mike Mike B. Feher, EOZ Inc. 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 office 908-901-9193 cell -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Richard (Rick) Karlquist Sent: Monday, November 15, 2010 4:44 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] 5 and 10 MHz crystal filters A friendly warning about crystal filters. Crystals, whether used in an oscillator or filter, have intrinsic phase noise. You cannot improve the phase noise of a crystal oscillator with a crystal filter unless the filter crystals have lower phase noise than the oscillator crystals. In general, post filtering of an oscillator is rarely done for the reasons I mentioned. One place where it made sense was in the HP 8662 with the 640 MHz output option where a 10811 is multiplied to 80 MHz and then filtered to reduce the noise floor. It is further multiplied to 640 MHz and filtered again by a SAW filter, that was made at HP in those days. As others have mentioned, filter characteristic impedance is a function of the crystal physics. There is a specific impedance that you must use for a given bandwidth. Fortunately, it is easy to put transformers at the ports to convert to 50 ohms. Rick Karlquist N6RK On 11/15/2010 7:44 AM, John Ackermann N8UR wrote: I'd like to find a couple of 5.0 and/or 10.0 MHz crystal filters, preferably configured for use in-line with 50 ohm coax. I've done some googling but don't find anyone selling these as a stock item. Do they exist? Any pointers would be appreciated. Used/surplus is fine (even preferable). Thanks! John ___ 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] 5 and 10 MHz crystal filters
I hadn't considered phase noise, thanks for bringing that up! I know tempo can also be an issue with high Q filters. These aren't significant issues for my current application, which is to clean up a synthesizer running at a slight offset from the nominal 10.000 MHz frequency. So I'm starting with much more noise than an OCXO. John On Nov 15, 2010, at 4:43 PM, Richard (Rick) Karlquist rich...@karlquist.com wrote: A friendly warning about crystal filters. Crystals, whether used in an oscillator or filter, have intrinsic phase noise. You cannot improve the phase noise of a crystal oscillator with a crystal filter unless the filter crystals have lower phase noise than the oscillator crystals. In general, post filtering of an oscillator is rarely done for the reasons I mentioned. One place where it made sense was in the HP 8662 with the 640 MHz output option where a 10811 is multiplied to 80 MHz and then filtered to reduce the noise floor. It is further multiplied to 640 MHz and filtered again by a SAW filter, that was made at HP in those days. As others have mentioned, filter characteristic impedance is a function of the crystal physics. There is a specific impedance that you must use for a given bandwidth. Fortunately, it is easy to put transformers at the ports to convert to 50 ohms. Rick Karlquist N6RK On 11/15/2010 7:44 AM, John Ackermann N8UR wrote: I'd like to find a couple of 5.0 and/or 10.0 MHz crystal filters, preferably configured for use in-line with 50 ohm coax. I've done some googling but don't find anyone selling these as a stock item. Do they exist? Any pointers would be appreciated. Used/surplus is fine (even preferable). Thanks! John ___ 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] HP 3048A Phase Noise Measurement System Accessories / Options
John, Hi, recently I added a nice 11848A phase noise interface to the herd. It came with the options K23 (DC Blocking Filter) and K21 (AM Detector Filter), including the complete set of adapters, manuals and matching / calibration networks. If anyone is interested, I'll be happy to scan the manuals. I think these are not yet out on the web. I've uploaded my cal, ops, and ref manual scans to http://www.hparchive.com (see the Equipment link under '3048A' near the bottom of the page), as well as two different editions of the 11848A service manual, but I don't think I've seen any schematics for the various option modules. Would be good to add those to the page. PM sent with the K23 DC blocking filter manual. I'll scan the K21 AM detector filter, too. Another interesting detail: The 11848A has options 201, 300 and H26. H26 appears to denote the opt 201 microwave phase detector with extended frequency range to 26.5 GHz (with male 3.5 connectors on the front panel). I've never seen that option before. I have no idea what 300 stands for though. Sounds like a nice box. Did it come with any software? Since option 301 was the MS-DOS version, maybe 300 refers to another software option, possibly a customer-specific mod to support the 26.5 GHz mixer. It came in near mint condition with two original accessory boxes containing the options and the 'Series 200/300 Rev. A.03.02 (Compiled for RMBUX)' software. I would appreciate to hear about any other options and accessories for the 3048A / 11848A that are not covered by the common manuals. Btw. are there any known projects to run the 3048A on HP/Agilent VEE or other nowadays environments? Not on VEE, but you can run it under the Transera HTBasic emulator (including the free trial version) using this modified version: http://www.ke5fx.com/3048A_X01.zip . (I'm not the author but I can probably help you get it running if you have any trouble, since I've used it heavily.) -- john, KE5FX Many thanks! I have a working 3048A with the MS-DOS version, but would be happy to run it on a PC that can be connected to my network. So, the Transera solution sounds like a plan! Thank you very much! Nevertheless, if anyone has de-embedded the instrument control and calibration sequences, that would be great for more experimentation. Adrian ___ 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] HP 3048A Phase Noise Measurement System Accessories / Options
PM sent with the K23 DC blocking filter manual. I'll scan the K21 AM detector filter, too. It hasn't shown up -- it might've been too big to email. Anything over a couple MB should go to jmiles (at) gmail.com, with a note to jmiles (at) pop.net to let me know you sent it. I have a working 3048A with the MS-DOS version, but would be happy to run it on a PC that can be connected to my network. So, the Transera solution sounds like a plan! Thank you very much! Nevertheless, if anyone has de-embedded the instrument control and calibration sequences, that would be great for more experimentation. I started down that path (see http://www.ke5fx.com/11848a.htm) but didn't end up pursuing it very far before getting distracted with other things... -- john, KE5FX ___ 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 sensors and bridge amps
Harry Brown wrote: Back in the early 80's I was working for a company making military communication satellites. The 5 MHz Oscillators used on the satellite were in a double oven keeping the oven temp within 0.001 Hz C. We could adjust the oscillator frequency for aging by ground commanding a bank of relays controlled a D/A converter to adjust the oscillator frequency. Lots of fun back then. Any idea what is used now? there's a variety of oscillators used on satellites these days. It kind of depends on the specific application. For science satellites, a lot of stuff is done with two way ranging, so the onboard oscillator only needs to be good enough to allow it to acquire the signal from earth. TCXOs are good for the 0.5 ppm sort of performance. Nice and low power. OCXOs are somewhat better, at the cost of more power consumption USOs (a OCXO in a vacuum bottle, with a very fancy crystal and electronics) are used where very good performance is needed. ppb per year stability over time, 1E-12 over temp, but volumes around a liter, mass around 0.5 kg and powers around a watt There's development of a trapped mercury ion clock underway, which should improve performance by several orders of magnitude. There are also flight qualified Rb and Cs sources being used, on GPS satellites among others. There's also experimental stuff with disciplining non tcxo oscillators against GPS and similar schemes. That should get performances comparable to other terrestrial GPSDOs ___ 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 sensors and bridge amps
Bill Hawkins wrote: Harry, What's the ambient temperature swing for the outer oven in space? Bill Hawkins That would depend (a lot) on the thermal design of the spacecraft. We typically design for a temperature range of -20C to +70C, but we don't expect to see anywhere near that sort of variation on orbit. That range is more to make sure it works every time. A piece of equipment on a typical LEO satellite might see 5-10 degree variations in temperature at the baseplate during the 100 minute revolution, depending on where the orbit is relative to the sun (if you go in and out of eclipse, the variations are bigger). A lot of satellites have smaller variations on a hour to hour basis, but might have a 5-10 degree change over the seasons. Radios on Mars rovers and the like see pretty big temperature fluctuations between night and day (many tens of degrees C), although, again, specifics of design make a difference. For instance, if you've got enough battery, you can run heaters during the night. RHU(Radioactive Heating Units) help limit the minimum temperature. On deep space, the temperature fluctuations are very small.. solar loading is pretty constant, attitude is usually kept the same, etc. The changes are when different instruments are turned on and off, or if you change attitude to point a sensor somewhere. ___ 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.
