Re: [time-nuts] Lamp oven repair info for HP 5065A
Chuck I suspect it actually is for you. As you say you now have a great deal of insight that you did not before and as I have often read here. Its funny how we have all learned about the nasty effects of age. Ahhh I mean equipment that is. So I would bet you could get it going. The RB elements in the 5065 seem to last a long time its worth a shot. Kind of like the HP 5060/5061 was worth a shot and I learned a lot. Can't help that it actually works now. That was unexpected. Bythe waythat effort sort of cured me of the I want a CS. :-) Regards Paul WB8TSL On Sun, Aug 2, 2015 at 6:36 PM, Chuck Harris cfhar...@erols.com wrote: The main oven on my 5065A was made with a bifilar winding of enamel covered nichrome wire wound directly on the aluminum oven. To cancel the magnetic field, the far end of the coil was shorted, making the heater a hairpin loop No twist that I recall... The enamel was compromised somewhere along the winding, causing it to put the oven into thermal runaway, thus toasting the lamp assembly. (this was my first exposure to how stupid HP could be with some of the designs they made...) The runaway oven got hot enough to reflow the solder, and cause several parts to fall out of the lamp's circuit board... the board was turned into just plain old fiber glass matting, as all of the epoxy... or whatever it was, turned to charcoal. When I did this stuff, I was fresh out of EE school, the web didn't yet even exist as an idea, and I knew nothing about how rubidium standards worked I knew they were special, so I called up HP, and ordered a $300 manual... but I digress... My first fix was to disassemble the oven, and wrap it with a solenoid of teflon insulated heating wire. It worked nicely, except that it made a magnetic field, and shifted the frequency with temperature.. Whack!... DOH! Next, I found some thin coaxially shielded nichrome wire meant for I know not what... maybe electric blankets? And put a crimp on connector at the far end to make a coaxial hairpin loop. I tightly wound that around the oven, and used great stuff urethane foam to replace the oven's insulation. It worked quite well, until the next thing went wrong, and I put the reference on my to be fixed someday shelf where it has lived ever since. Back then, I didn't know anything about capacitor plague, and carbon composition resistor drift, and all the usual failure modes of HP equipment... I ought to take it off of the shelf and give it a go once again... should be easy... for an engineer that now has 35 years more experience... Right? -Chuck Harris cdel...@juno.com wrote: Hi, Just thought I'd share some info on repairing a defective HP 5065A lamp oven. These ovens can fail either shorted to the oven cylinder or have interwinding shorts. I have repaired three optical units so far with this failure. The original winding was insulated twisted pair wound directly onto the Aluminum oven cylinder. I used teflon insulated heater wire, Pelican P2332ADVFEP.009BL. It is approx. 5 Ohms/ft. and I use a 50 Ohm length doubled and then twisted tightly. This is then wound onto the oven cylinder which is first covered with a single layer of kapton tape. The original thermistor is replaced with a DigiKey 615-1007-ND. The thermistor MUST be surrounded by heat sink compound. I also install a digiKey TO220 100 degree thermal cutout switch for future protection. It is mounted to the top of the lamp assy. using one of the 3 original mounting screws. The thermistor and heater wires are brought out tie wrapped along the original cable and then soldered to the appropriate pins on the db9 connector. Cheers, Corby ___ 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] KS Lucent RFTG-u power supply
I bought several of these, 19.5 V 4.75A power supplies from user shunwei2014 on the auction site. http://www.ebay.com/itm/201159335516?_trksid=p2057872.m2749.l2649ssPageName=STRK%3AMEBIDX%3AIT I have no association other than being a customer. One of these power supplies freed my lab power supplies in powering both L101 and L102 boxes from cold to running, at $7.99. 73, Ian, G4ICV, AB2GR -- ___ 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] Lab upgrade
The fault was found by somebody with a heck of a lot more experience than yours truly. Turns out the 5v regulator had shorted out, a protection diode did it's thing and popped the fuse protecting the rest of the system. J. On 29 Jul 2015 2:49 am, Robert LaJeunesse lajeune...@mail.com wrote: One of the cheap and dirty ways to find a short is current tracing. Use a voltage and current limited source and a matching detector to find where the current flows. I've used a current limited DC supply as the source and, for the detector, an old DVM with 10uV resolution. For an AC approach a simple audio oscillator (or function generator) works nicely as the source, while a the detector starts with an audio playback tape head (from an old VCR), then some sort of amplifier-speaker, or maybe just an oscilloscope. If you are lucky you have an old HP logic pulser and current tracer set that do the same thing... Bob L. ... I'll buzz out the pins on the connnector there and see if I can find the probably short and let people know. Cheers Jason ___ 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] Data Collection for Allan Deviation
Hi A few thoughts: On Aug 1, 2015, at 9:34 PM, Bob Stewart b...@evoria.net wrote: Hi Bob, I believe that the approach I used in the example plot I linked in the other post was PPS to ext/arm, GPSDO 10MHz to start, Cs 10MHz to stop. So, is this a methodology issue, then? Is the pps from a third source? 1) That adds an “arm to start” delay into the mix. I would *hope* it’s stable, but no guarantees…. 2) You will pick up the “next zero cross” on the GPSDO 10 MHz (so another variable delay) as start 3) You will then measure to the “next zero cross” on the Cs Effectively you have two possibilities for phase slip and no real improvement in measurement accuracy. If the PPS edge is ambiguous, your GPSDO edge selection will be suspect. You also now have three (not just two) signals to “get noisy” and mess things up. A “more better” way to go: PPS to start input Fast clock to stop input Stream the data out however you are set up do do so (varies from counter to counter) With a GPIB counter running in full control mode, you will need to sync your data process to the 1 pps. With a GPIB counter in talk only mode, you just need to grab the data when it arrives With a serial output counter, the data just shows up In all cases you need to validate you setup. You should get one reading a second, not two closely spaced readings. A 2 second gap between readings is also a bad sign. Since the checks are in the “I can time it by eyeball” range, they aren’t terribly complex to set up. Bob Bob From: Bob Camp kb...@n1k.org To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Saturday, August 1, 2015 8:22 PM Subject: Re: [time-nuts] Data Collection for Allan Deviation Hi Which approach are you using: 1) start with 1 pps, stop with 10 MHz (max period ~ 100 ns) 2) start with 1 pps stop with 1 pps (max period ~ 1 second) Each has it’s own set of issues. A 1% error on 100 ns is at the noise on a 5335. Both counters need a pretty accurate reference if they are running out in the half second or more region. The 10811 in the 5370 should be 1x10^-11 at one second unless you have an unusual poor example. It should hold 3x10^-10 per day if it’s been on power for 30 days or more and not been abused. Bob On Aug 1, 2015, at 2:57 PM, Bob Stewart b...@evoria.net wrote: Hi Poul, 0) Make sure that the counter does not get its reference frequency from any of the input signals. Does your rule 0 hold if one of the input signals is a Cs standard? I believe I've posted in the past that the ADEV from 1 tau to 100 tau is a bit noisy if I use the internal 10811 to clock the 5370A. I noticed the same on my 5335A. Bob From: Poul-Henning Kamp p...@phk.freebsd.dk To: Discussion of precise time and frequency measurement time-nuts@febo.com; zzsili...@post.com Sent: Saturday, August 1, 2015 4:19 AM Subject: Re: [time-nuts] Data Collection for Allan Deviation In message trinity-fbe15ceb-78c6-4e04-a3e1-b9b5c2e20fd9-1438400665333@3capp-ma ilcom-lxa02, zzsili...@post.com writes: If I have a GPS receiver with output pin of both 1pps 10KHz, a Rubidium clock of 10MHz, and a signal generator. How can I determine their Allan Deviation? I know the math formula, but my problem is the data collection. Presuming you have a counter which can measure Time Interval between two signals. 0) Make sure that the counter does not get its reference frequency from any of the input signals. If one of your signals is 1PPS: 1) Connect 1PPS to START 2) Connect other signal to STOP 3) Collect TI measurements. else: 1) Connect signal with lowest frequency to START 2) Connect signal with highest frequency to STOP 3) Trigger measurements at 1Hz rate, either through EXT TRIG or GPIB For this to work, the signals must be sufficient on-frequency that the phase-wrap-arounds (when the STOP signal slips past the START signal) can be resolved afterwards. A good rule of thumb is that the flanks of the START/STOP signals should not move more than 1/3 the period of the higher frequency signal in the time between measurements (= 1sec above). I use my own home-grown program to calculate the MVAR. The Lady Heather program should be able to do it with data collected this way. -- 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. ___ time-nuts mailing list -- time-nuts@febo.com
Re: [time-nuts] Data Collection for Allan Deviation
In message 1502052008.304624.1438465781711.javamail.ya...@mail.yahoo.com, Bob Stewart writes: Here's an example of what I'm talking about. See description and notes. The blue trace is the one using the clock in the 5370A. The other tests match pretty closely down to around 60s or so. http://evoria.net/AE6RV/5370A/Test1.png As a general principle: Until you know why they differ, always trust the worst measurement rather than the best measurement. The waves on the blue line could indicate a spur which is not at a multiple of your basic sampling frequency (1Hz) -- 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.
[time-nuts] Fwd: Re: Square to sine wave symmetrical conversion (part 2)
[I could not see this echoed by the server on the 1st try. ] Am 28.07.2015 um 03:58 schrieb Bill Byrom N5BB: [ nice and understandable summary of the Lee / Hajimiri ideas ] OTOH with this Dirac-style resonator feeding, one collects the noise sidebands from order 1 to MAXINT and one needs to align all these harmonics nicely. It also does not help against low frequency effects that require stability over many cycles, such as the 1/f region. And it is only half the work. We not only need to feed the resonator, we also want RF from it. Thus, to stay with this principle, the sustaining amplifier would have to fetch its input also in Dirac style. Now we are pretty close to an ultra wideband nonlinear loop gain. Any low pass filtering will have to be done in front of the feeding pulse former, or the harmonics will not align. And apart from BW limiting we need something to set the net loop phase to 0. The pulse output of the sustaining amplifier is also not nice to use unless we want to feed a sampler or 1:2-FlipFlop. Output filtering via the resonator, say, in the elegant Burgeon(?) style would also be forbidden. As I see it, L/H creates a lot of problems, and worse, it does not provide a design algorithm, even if we accept the complications. regards, Gerhard, DK4XP (Arghh, I'm writing this on a 4*2 thread machine at 3.8 GHz, and Thunderbird produces typing delays... Turbo-C on Z80 with a Wyse-50 terminal felt better.) ___ 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] Modified Allan Deviation and counter averaging
Hi Poul-Henning, On 08/01/2015 10:32 PM, Poul-Henning Kamp wrote: In message 49c4ccd3-09ce-48a4-82b8-9285a4381...@n1k.org, Bob Camp writes: The approach you are using is still a discrete time sampling approach. As such it does not directly violate the data requirements for ADEV or MADEV. As long as the sample burst is much shorter than the Tau you are after, this will be true. If the samples cover 1% of the Tau, it is very hard to demonstrate a noise spectrum that this process messes up. So this is where it gets interesting, because I suspect that your 1% lets play it safe threshold is overly pessimistic. I agree that there are other error processes than white PM which would get messed up by this and that general low-pass filtering would be much more suspect. But what bothers me is that as far as I can tell from real-life measurements, as long as the dominant noise process is white PM, even 99% Tau averaging gives me the right result. I have tried to find a way to plug this into the MVAR definition based on phase samples (Wikipedia's first formula under Definition) and as far as I can tell, it comes out the same in the end, provided I assume only white PM noise. I put that formula there, and I think Dave trimmed the text a little. For true white PM *random* noise you can move your phase samples around, but you gain nothing by bursting them. For any other form of random noise and for the systematic noise, you alter the total filtering behavior as compared to AVAR or MVAR, and it is through altering the frequency behavior rhat biases in values is born. MVAR itself has biases compared to AVAR for all noises due to its filtering behavior. The bursting that you propose is similar to the uneven spreading of samples you have in the dead-time sampling, where the time between the start-samples of your frequency measures is T, but the time between the start and stop samples of your frequency measures is tau. This creates a different coloring of the spectrum than if the stop sample of the previous frequency measure also is the start sample of the next frequency measure. This coloring then creates a bias-ing depending on the frequency spectrum of the noise (systematic or random), so you need to correct it with the appropriate biasing function. See the Allan deviation wikipedia article section of biasing functions and do read the original Dave Allan Feb 1966 article. For doing what you propose, you will have to define the time properities of the burst, so that woould need to have the time between the bursts (tau) and time between burst samples (alpha). You would also need to define the number of burst samples (O). You can define a bias function through analysis. However, you can sketch the behavior for various noises. For white random phase noise, there is no correlation between phase samples, which also makes the time between them un-interesting, so we can re-arrange our sampling for that noise as we seem fit. For other noises, you will create a coloring and I predict that the number of averaged samples O will be the filtering effect, but the time between samples should not be important. For systematic noise such as the quantization noise, you will again interact, and that with a filtering effect. At some times the filtering effect is useful, see MVAR and PVAR, but for many it becomes an uninteresting effect. But I have not found any references to this optimization anywhere and either I'm doing something wrong, or I'm doing something else wrong. I'd like to know which it is :-) You're doing it wrong. :) PS. At music festival, so quality references is at home. 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.
[time-nuts] Output MMIC in Lucent Rb units....
Hello, Does anyone know model of MMIC that is used in output stage of 15 MHz amplifier chain in Lucent Rb units? It is pretty large ceramic case with gold plated covers. For example, it is U4 on a following board photo. http://www.makarov.ca/images/rubidium/Lucent%20011.jpg The same MMIC was seen in at least two other (older) models of Lucent Rb units, based on Efratom FRS-C. -- Sincerely, Yuri mailto:y...@ostry.ru ___ 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] Measurement resolution to be improved
Hi, For the measurement of Allan Deviation my configuration consists of a HP53132A and TIMELAB. I verified that the best resolution is using the universal counter as a frequency counter. Using the time interval counter with 1 PPS input is definitely has a more precise measurement but the resolution collapses dramatically making useless measurements on DUT with good/excellent stability. I tried to use the Dual Mixer Time Difference but the Phase Wrap is very difficult to manage during the measurements and so I abandoned the project. I have no specific experience but it seems to me that a good solution is the one applied in the A7 Quartzlock, very expensive machine and hard to find used in hobbyist prices. I'd like to find a solution that would allow me to improve a hundred times or more the resolution that I currently have with my setup without sacrificing TIMELAB. The question I ask you is this: is there a solution to this problem with features want from me with costs under 1500 dollars/euros? Luciano timeok Message sent via Atmail Open - http://atmail.org/ ___ 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] HP10811 dual oven
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 Message sent via Atmail Open - http://atmail.org/ ___ 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] Lamp oven repair info for HP 5065A
Hi, Just thought I'd share some info on repairing a defective HP 5065A lamp oven. These ovens can fail either shorted to the oven cylinder or have interwinding shorts. I have repaired three optical units so far with this failure. The original winding was insulated twisted pair wound directly onto the Aluminum oven cylinder. I used teflon insulated heater wire, Pelican P2332ADVFEP.009BL. It is approx. 5 Ohms/ft. and I use a 50 Ohm length doubled and then twisted tightly. This is then wound onto the oven cylinder which is first covered with a single layer of kapton tape. The original thermistor is replaced with a DigiKey 615-1007-ND. The thermistor MUST be surrounded by heat sink compound. I also install a digiKey TO220 100 degree thermal cutout switch for future protection. It is mounted to the top of the lamp assy. using one of the 3 original mounting screws. The thermistor and heater wires are brought out tie wrapped along the original cable and then soldered to the appropriate pins on the db9 connector. Cheers, Corby ___ 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] Source of Rubidium Lamp for Efratom FRK
Thanks Chuck and Bob for the further comments. I have actually had a reply from Sematron. Seems that the lamps are still available at only £781.63 - call it $1,100! Since that probably buys four Racal 9475s when they appear, I think I might go the other route. I also think that the lazy approach applies at present i.e. do nothing unless the unit packs up. Nobody else has commented on whether the same bulb is used in other Efratom Rb sources, so I will leave it there. Again, thanks for all your feedback. Mike Friday, 31 July, 2015 20:02 Chuck Harris wrote: Hi Mike, That bulb was sealed with an oxy-fuel torch at the melting point of the glass. It was then annealed, starting at a much higher temperature than 150C before cooled slowly to avoid breaking. Heat it uniformly with your hot air gun until it is no longer black. Reducethe heat slowly to allow it to cool... or, you can toss it into a can full of white ashes from your fireplace. Or, leave it be and wait until it really fails before fixing it. -Chuck Harris ___ 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] Everything you wanted to know about Oscillators
Interesting video. http://hackaday.com/2015/08/01/everything-you-wanted-to-know-about-oscillators/ -=Bryan=- ___ 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] Measurement resolution to be improved
Hi On Aug 2, 2015, at 3:18 AM, tim...@timeok.it wrote: Hi, For the measurement of Allan Deviation my configuration consists of a HP53132A and TIMELAB. I verified that the best resolution is using the universal counter as a frequency counter. True, but the counter “lies to you in this mode when you are doing ADEV. Using the time interval counter with 1 PPS input is definitely has a more precise measurement but the resolution collapses dramatically making useless measurements on DUT with good/excellent stability. The readings in the frequency mode are equally useless for ADEV. The frequency estimation process is not compatible with ADEV. I tried to use the Dual Mixer Time Difference but the Phase Wrap is very difficult to manage during the measurements On a reasonably stable device with a rational beat note that should not be a problem. I suspect that either: 1) Your beat note is to low relative to the frequencies you art trying to measure (to much gain) -and / or- 2) Your beat note is to low relative to the stability of the devices you are looking at (again to much gain). Without more details it’s tough to go much further than those two suggestions. and so I abandoned the project. I have no specific experience but it seems to me that a good solution is the one applied in the A7 Quartzlock, very expensive machine and hard to find used in hobbyist prices. I'd like to find a solution that would allow me to improve a hundred times or more the resolution that I currently have with my setup without sacrificing TIMELAB. The TimePod from Symmetricom is currently the lowest cost general purpose device I know of on the market. The question I ask you is this: is there a solution to this problem with features want from me with costs under 1500 dollars/euros? I’d contact Symmetricom / Microsemi for current prices. Bob Luciano timeok Message sent via Atmail Open - http://atmail.org/ ___ 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] HP10811 dual oven
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 Message sent via Atmail Open - http://atmail.org/ ___ 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] Everything you wanted to know about Oscillators
On Sat, 1 Aug 2015 18:18:18 -0700 Bryan _ bpl...@outlook.com wrote: http://hackaday.com/2015/08/01/everything-you-wanted-to-know-about-oscillators/ Yes, not too bad. But when you actually want to know what makes an oscillator tick, i would rather recommend [1] as a treatment of general electronic oscillators. If that is too theoretic, then [2] provides a more practical approach. [3] is a quite nice treatment of various transistor based oscillators, but also covers the more advanced stuff like noise in oscillators. When it comes to quartz oscillators, then [4] and [5] are pretty much the standard literature. If all of these are too long, then have a look at Ulrich Rohdes dissertation [6]. Attila Kinali [1] Foundations of Oscillator Circuit Design, by Guilermo Gonzales, 2007 [2] Practical Oscillator Handbook, by Irving M. Gottlieb, 1997 [3] The Design of Modern Microwave Oscillators for Wireless Applications, by Rohde, Poddar, Böck, 2005 [4] Design of Crystal and Other Harmonic Oscillators, by Benjamin Parzen, 1983 [5] Crystal Oscillator Design and Temperature Compensation, by Marvin Frerking, 1978 [6] A New and Efficient Method of Designing Low Noise Microwave Oscillators, by Ulrich Rohde, 2004 https://opus4.kobv.de/opus4-tuberlin/frontdoor/deliver/index/docId/916/file/rohde_ulrich.pdf -- I must not become metastable. Metastability is the mind-killer. Metastability is the little-death that brings total obliteration. I will face my metastability. I will permit it to pass over me and through me. And when it has gone past I will turn the inner eye to see its path. Where the metastability has gone there will be nothing. Only I will remain. ___ 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] Everything you wanted to know about Oscillators
These are better summary papers : http://www.qsl.net/va3iul/Phase%20noise%20in%20Oscillators.pdf http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.309.5449rep=rep1t ype=pdf 73 de Ulrich N1UL In a message dated 8/2/2015 6:24:05 P.M. Eastern Daylight Time, ka2...@aol.com writes: well, the Pierce oscillator does not give that much freedom, the steady state loop gain should be Pi (about 3) as the RF Gm = Gmo/pi. This analysis does not address the important SSB noise gut guaranties oscillation. In testing enough a loaded Ql of Qp/2 is best for power matching and good phase noise. Too much loading no selectivity, not enough loading too much resonator insertion loss, far off noise. Life is full of compromises. 73 de Ulrich N1UL In a message dated 8/2/2015 6:06:35 P.M. Eastern Daylight Time, bpl...@outlook.com writes: Interesting video. http://hackaday .com/2015/08/01/everything-you-wanted-to-know-about-oscillators/ -=Bryan=- ___ 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] Modified Allan Deviation and counter averaging
In message 55bdb002.8060...@rubidium.dyndns.org, Magnus Danielson writes: For true white PM *random* noise you can move your phase samples around, but you gain nothing by bursting them. I gain nothing mathematically, but in practical terms it would be a lot more manageable to record an average of 1000 measurements once per second, than 1000 measurements every second. For any other form of random noise and for the systematic noise, you alter the total filtering behavior [...] Agreed. -- 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] Everything you wanted to know about Oscillators
well, the Pierce oscillator does not give that much freedom, the steady state loop gain should be Pi (about 3) as the RF Gm = Gmo/pi. This analysis does not address the important SSB noise gut guaranties oscillation. In testing enough a loaded Ql of Qp/2 is best for power matching and good phase noise. Too much loading no selectivity, not enough loading too much resonator insertion loss, far off noise. Life is full of compromises. 73 de Ulrich N1UL In a message dated 8/2/2015 6:06:35 P.M. Eastern Daylight Time, bpl...@outlook.com writes: Interesting video. http://hackaday.com/2015/08/01/everything-you-wanted-to-know-about-oscillato rs/ -=Bryan=- ___ 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] Source of Rubidium Lamp for Efratom FRK
Hi That’s about the right price relative to the last time I bought any of them. Bob On Aug 2, 2015, at 10:33 AM, Mike Niven mfni...@ymail.com wrote: Thanks Chuck and Bob for the further comments. I have actually had a reply from Sematron. Seems that the lamps are still available at only £781.63 - call it $1,100! Since that probably buys four Racal 9475s when they appear, I think I might go the other route. I also think that the lazy approach applies at present i.e. do nothing unless the unit packs up. Nobody else has commented on whether the same bulb is used in other Efratom Rb sources, so I will leave it there. Again, thanks for all your feedback. Mike Friday, 31 July, 2015 20:02 Chuck Harris wrote: Hi Mike, That bulb was sealed with an oxy-fuel torch at the melting point of the glass. It was then annealed, starting at a much higher temperature than 150C before cooled slowly to avoid breaking. Heat it uniformly with your hot air gun until it is no longer black. Reducethe heat slowly to allow it to cool... or, you can toss it into a can full of white ashes from your fireplace. Or, leave it be and wait until it really fails before fixing it. -Chuck Harris ___ 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] Lamp oven repair info for HP 5065A
The main oven on my 5065A was made with a bifilar winding of enamel covered nichrome wire wound directly on the aluminum oven. To cancel the magnetic field, the far end of the coil was shorted, making the heater a hairpin loop No twist that I recall... The enamel was compromised somewhere along the winding, causing it to put the oven into thermal runaway, thus toasting the lamp assembly. (this was my first exposure to how stupid HP could be with some of the designs they made...) The runaway oven got hot enough to reflow the solder, and cause several parts to fall out of the lamp's circuit board... the board was turned into just plain old fiber glass matting, as all of the epoxy... or whatever it was, turned to charcoal. When I did this stuff, I was fresh out of EE school, the web didn't yet even exist as an idea, and I knew nothing about how rubidium standards worked I knew they were special, so I called up HP, and ordered a $300 manual... but I digress... My first fix was to disassemble the oven, and wrap it with a solenoid of teflon insulated heating wire. It worked nicely, except that it made a magnetic field, and shifted the frequency with temperature.. Whack!... DOH! Next, I found some thin coaxially shielded nichrome wire meant for I know not what... maybe electric blankets? And put a crimp on connector at the far end to make a coaxial hairpin loop. I tightly wound that around the oven, and used great stuff urethane foam to replace the oven's insulation. It worked quite well, until the next thing went wrong, and I put the reference on my to be fixed someday shelf where it has lived ever since. Back then, I didn't know anything about capacitor plague, and carbon composition resistor drift, and all the usual failure modes of HP equipment... I ought to take it off of the shelf and give it a go once again... should be easy... for an engineer that now has 35 years more experience... Right? -Chuck Harris cdel...@juno.com wrote: Hi, Just thought I'd share some info on repairing a defective HP 5065A lamp oven. These ovens can fail either shorted to the oven cylinder or have interwinding shorts. I have repaired three optical units so far with this failure. The original winding was insulated twisted pair wound directly onto the Aluminum oven cylinder. I used teflon insulated heater wire, Pelican P2332ADVFEP.009BL. It is approx. 5 Ohms/ft. and I use a 50 Ohm length doubled and then twisted tightly. This is then wound onto the oven cylinder which is first covered with a single layer of kapton tape. The original thermistor is replaced with a DigiKey 615-1007-ND. The thermistor MUST be surrounded by heat sink compound. I also install a digiKey TO220 100 degree thermal cutout switch for future protection. It is mounted to the top of the lamp assy. using one of the 3 original mounting screws. The thermistor and heater wires are brought out tie wrapped along the original cable and then soldered to the appropriate pins on the db9 connector. Cheers, Corby ___ 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.
