[time-nuts] Microscope for SMT work...

Ian, You have a very nice setup. I also bought an AM-Scope about three years ago. Mine has the associated 8-bazillion ton white stand on the edge of the bench with double arms that lets me swing it over to where I'm working. As I recall, it has a zoom range of about 3.5 to 45x which is

Re: [time-nuts] Thermal impact on OCXO

Well bob's comments & caution are accurate, everything drifts. In your case, if the OCXO is rock solid then you would see a 160 PPM change on the EFC line over 7 days which is a 1mV change on your 6 V full scale, which is fairly easy to measure if you have a 6 1/2 digit DMM. On Sat, Nov 5, 2016

Re: [time-nuts] Thinking outside the box a super reference

On Sat, 05 Nov 2016 12:25:35 + "Poul-Henning Kamp" wrote: > >Active maser like the hydrogen would be possible naturally, but would > >require the resonator. > > I don't think they are. They are. It took a while, but they have been a thing since '64. Though all of

Re: [time-nuts] Thinking outside the box a super reference

On Sat, 5 Nov 2016 06:53:45 -0700 jimlux wrote: > On 11/5/16 2:59 AM, Attila Kinali wrote: > But we still need to ensure that the field is properly > > oriented and homogenous over the whole vapor cell. For this you need > > a cavity that is properly designed and most

[time-nuts] Corby Dawson Super 5065a work can I use a miniature Rubidium

Anton, To answer both questions: You can use a Laser in place of the Rubidium lamp, however assuming the problem is the lamp it would be cheaper to buy several LPRO units to scavenge for a replacement lamp. How did you determine it's the lamp that is dead? Using a Laser is more complicated

Re: [time-nuts] Thermal impact on OCXO

Hi Bob, Sadly, all I have is what I have.  The GSPDOs are in an unvented Hammond aluminum case.  I've got a thermistor on the bottom side of the board.  Actually, it's right below the PIC, so the temperature from the PIC would seem to be the driver of what I see.  Except that I've also done

Re: [time-nuts] Man with too many clocks.

I agree that FE-5680 is a whole family of products with very different features and these can not deducted from the labels. In my case I own a FE-5680A which outputs 1 PPS and a fixed (but slightly tunable) 10 MHz and needs 2 power supply voltages, +5 V and + 15 V. I am sending directly to

Re: [time-nuts] Man with too many clocks.

Hi A ten or twenty turn pot on a normal EFC will get you past the point that you can reasonably set the oscillator. The typical (not GPS version) EFC is down around 1 to 2 x 10^-7. A 20 turn pot will be running 1x10^-8 per turn. 100 to 200 points per turn is a pretty typical “set” number for a

Re: [time-nuts] Thermal impact on OCXO

Hi You have a first order, second order and third order coefficient to the temperature rate dependance on a crystal. Since the second order term is a square, it does not care about the sign of the rate. Bob > On Nov 4, 2016, at 9:56 PM, Bob Stewart wrote: > > In the

Re: [time-nuts] Man with too many clocks.

I own a 5680b and while it only outputs a PPS signal there is a very stable 30MHz signal available inside the unit IIRC. I can dig mine out and find the signal if that's of use? I believe they can be modded for 10MHz output on the 15p D type but I've just not managed to find time to get around

Re: [time-nuts] Thermal impact on OCXO

Sounds like you already realized this. Phase is the integral of frequency and the derivative of phase (phase rate) is frequency. So if you go from nominal frequency - slow - nominal or equivalently nominal frequency - fast - nominal the phase integrates up/down. It would be a little more

Re: [time-nuts] Man with too many clocks.

HI If you use a good wire wound pot and run it off of and oscillator EFC source (not all have them), the temperature effect is pretty much zero. You are using the pot as a ratio device. A mechanical cap that is part of the heated region of the OCXO (the normal case) has already been taken

Re: [time-nuts] Newbie With a Z3801 Problem

Hi Mark, Thank you for working with the KS24361. Looking forward to when the program will be available. Any ideas on being able to use the 1 PPS signal out of the KS24361 to drive SL sound card calibration? It is a weird pulse and someone mentioned the timing is wrong. I use the pulse

Re: [time-nuts] Thinking outside the box a super reference

In message <0e976194-3cc1-2bc7-1289-0d9433132...@rubidium.dyndns.org>, Magnus D anielson writes: >> They won't be coherent photons, like in a Hydrogen maser, but we >> don't need them to be, in fact that just causes the same exact >> problems as the tuned cavity anyway, as long as we can

Re: [time-nuts] Thinking outside the box a super reference

One of the main limiting factors in the 5061 was microwave leakage. An excellent Italian engineer named DiMarchi mastered the so called "top cover effect", where removing the top cover changed the frequency. He had a small business going refurbishing 5061's by cleaning up the waveguide

Re: [time-nuts] Thermal impact on OCXO

Hi Scott and Bob and others, I keep telling myself that I won't get involved with the temperature problem, and yet for some reason I keep going down that rabbit hole.  It seems to me that it's one thing to correct well enough to stay on frequency within some degree of accuracy, and yet another

Re: [time-nuts] Thermal impact on OCXO

Hi Remember - most holdover specs also include a delta temperature (like 40 to 70C) during the holdover period …. Bob > On Nov 5, 2016, at 12:15 PM, Bob Stewart wrote: > > Hi Scott and Bob and others, > I keep telling myself that I won't get involved with the temperature

Re: [time-nuts] I love the smell of tantalum in the morning

On 11/5/16 12:12 PM, Tom Van Baak wrote: See C13 in the attached photo. I need to replace some blown caps on a few boards [1]. In one instance the cap got so hot it melted itself off the board. Quiet convenient, actually -- it acts like its own fuse -- but I don't think the 5071 designers had

Re: [time-nuts] Thermal impact on OCXO

> At 12 hours of holdover... > I think I'll need a lot more understanding of the impact of aging vs > temperature At that timescale, I'd expect aging to be lost in the noise. How are you calibrating things? -- These are my opinions. I hate spam.

Re: [time-nuts] Thinking outside the box a super reference

On 11/03/2016 06:10 PM, Attila Kinali wrote: On Thu, 3 Nov 2016 16:37:06 -0400 Ruslan Nabioullin wrote: What about instead establishing an open-source hardware project for a frequency standard fusor? I was researching COTS solutions for this for my rubidium ensemble

Re: [time-nuts] I love the smell of tantalum in the morning

Either hot tweezers or a hot air rework station are the best/easiest ways to remove dead parts. But two fine-tip soldering irons will also work and are a lot cheaper. The idea is to heat both ends of the part at once, and when the solder flows, lift or flip the part off. Then, use some

Re: [time-nuts] I love the smell of tantalum in the morning

Surprisingly the 852D+ which is a very cheap rework station is quite good. Quite a few reviews on the EEVblog. -=Bryan=- From: time-nuts on behalf of Bob Stewart Sent: November 5, 2016 12:18 PM To: Tom Van Baak;

Re: [time-nuts] Thermal impact on OCXO

Oh dear.  I attached the wrong file.  Here's the correct one.  - AE6RV.com GFS GPSDO list: groups.yahoo.com/neo/groups/GFS-GPSDOs/info ___ time-nuts mailing list -- time-nuts@febo.com

Re: [time-nuts] I love the smell of tantalum in the morning

Hi Tom, Personally, I wouldn't touch this without a hot air gun.  I don't know what your budget is.  What I consider reasonable may be an order of magnitude smaller than for you.  So, I use a generically labeled 852D+ rework combo.  It has both solder pencil and hot air gun.  There are better

Re: [time-nuts] I love the smell of tantalum in the morning

Metcal /OKI might be that other brand. I'd certainly recommend them, but the tweezers are not as fast to heat as the single tip devices. I've had little success personally with the hot air devices. I seem to toast the board before I melt the solder, and when it does melt it's not limited to one

Re: [time-nuts] Thinking outside the box a super reference

Attila, PHK, et al -- Rb maser proposal, including some photos. 3 PDF's, 175 pages of weekend reading: https://archive.org/details/NASA_NTRS_Archive_19720025867 https://archive.org/details/NASA_NTRS_Archive_19730017775 https://archive.org/details/NASA_NTRS_Archive_19750006044 /tvb

Re: [time-nuts] Thermal impact on OCXO

Hi Bob, Ugh!  40C to 70C is not something I plan to deal with.  If I were selling to a commercial market, that would be a different story.  But at my price point, not gonna happen.  But it does bring up the point that I need to have some sort of idea of what I'm willing to manage. Bob 

Re: [time-nuts] Thinking outside the box a super reference

On 11/05/2016 03:16 PM, Attila Kinali wrote: On Sat, 05 Nov 2016 12:25:35 + "Poul-Henning Kamp" wrote: Active maser like the hydrogen would be possible naturally, but would require the resonator. I don't think they are. They are. It took a while, but they have

Re: [time-nuts] Thermal impact on OCXO

Hi Hal, I don't think I understand your question.  So, I've attached a plot and you can tell me if that gives you anything to work with.  This uses my standard plotting script, so there are things you aren't interested in.  But, this is a plot of one unit from startup on the night of 10/29

Re: [time-nuts] Thinking outside the box a super reference

In message , "Tom Van Baak" writes: >Attila, PHK, et al -- > >Rb maser proposal, including some photos. 3 PDF's, 175 pages of weekend >reading: > >https://archive.org/details/NASA_NTRS_Archive_19720025867 >

Re: [time-nuts] I love the smell of tantalum in the morning

On Saturday, November 05, 2016 12:12:18 PM Tom Van Baak wrote: > See C13 in the attached photo. I need to replace some blown caps on a few > boards [1]. In one instance the cap got so hot it melted itself off the > board. Quiet convenient, actually -- it acts like its own fuse -- but I > don't

Re: [time-nuts] Logging SPAD pulses on synced devices (was: Linux PPS clues?)

Hi, and thank you for these suggestions. Currently this project becomes reality (slowly): this kind of synchronization/grabbing is very interesting, but I need something fast (I expect the SPAD with active quenching circuitry could output 30ns pulses, and the quantization frequency I hope to

Re: [time-nuts] Logging SPAD pulses on synced devices (was: Linux PPS clues?)

Ilia Circuit diagrams are  posted here from time to time, so it should be OK. Bruce On Saturday, 5 November 2016 7:02 PM, Ilia Platone wrote: Hi, and thank you for these suggestions. Currently this project becomes reality (slowly): this kind of

Re: [time-nuts] Logging SPAD pulses on synced devices

Attached to this mail there are three files: the APD.asc LTSpice4 simulation schematics, a model for the AD8561 comparator, a model for the VN2210 mosfet transistor, and a model for the BF959 bipolar transistor. Please note that the APD model included into the schematics may have errors: I

Re: [time-nuts] Thinking outside the box a super reference

In message <768ee5a7-1c53-06cf-cf36-ec75e2901...@karlquist.com>, "Richard (Rick) Karlquist" w rites: >Reminds me of an interesting Jack Kusters story. >There was some customer who was having problems with >his atomic clocks being noisy (I don't remember exactly >the story) but the

[time-nuts] Calibrating a HP 5370B Oscillator

Hi, Wrote:I am the proverbial man with too many clocks and I don'tknow what time it is. To correct this situation I have decided to calibrateeverything.   I have a HP 5370B, a HP6370A, and a HP 5328A all with the TCXO option.  Hi Peter, You can't really calibrate the 5370B oscillator.  I

Re: [time-nuts] Gentlemen: Synchronize Your Watches!

On Sat, 5 Nov 2016 04:19:08 + (UTC) Perry Sandeen via time-nuts wrote: > Time may be relative, but physicists are a stickler for accuracy. Ok.. the story without out the whole media mambojambo and mixup of things can be found at [1]. A description of the setup they used

Re: [time-nuts] Satellite TV messed up, how is GPS time

Satellite TV (Dish, Direct, etc) has been having trouble for 10 hours or so, sometimes losing some channels and occasionally all of them. Fox News is consistently down, so it could have a human cause, but Space Weather says we have unusual solar activity. I no longer have GPS time receivers,

Re: [time-nuts] I love the smell of tantalum in the morning

t...@leapsecond.com said: > Having not done SMT before, how should I do it with minimal risk to the > very precious PCB. Or, what equipment should I use this as a good excuse > to buy? If you can get at it, 2 soldering irons, one on each end, works reasonably well. When both ends are melted,

Re: [time-nuts] I love the smell of tantalum in the morning

Hi John, I've never used the hot tweezers.  I'm going to have to look into them.  Normally, for desoldering, I use a narrower nozzle with an elevated temperature - usually between 280C and 350C.  That blows the part completely off the pads just as soon as the solder flows, with little impact

Re: [time-nuts] I love the smell of tantalum in the morning

On Sat, Nov 05, 2016 at 12:12:18PM -0700, Tom Van Baak wrote: > Having not done SMT before, how should I do it with minimal risk to > the very precious PCB. Or, what equipment should I use this as a good > excuse to buy? Hello Tom. I do this kind of repairs quite often and as you have already

Re: [time-nuts] I love the smell of tantalum in the morning

I usually nibble away at the center of the part until it is two separate pieces. Then unsolder each piece. Clean the pads off with wick then install the new part. Use a good sharp pair of flush cut side cutters. Tom - Original Message - From: "Bob Camp" To: "Tom Van

Re: [time-nuts] I love the smell of tantalum in the morning

Dear Tom, On 11/05/2016 08:12 PM, Tom Van Baak wrote: See C13 in the attached photo. I need to replace some blown caps on a few boards [1]. In one instance the cap got so hot it melted itself off the board. Quiet convenient, actually -- it acts like its own fuse -- but I don't think the 5071

Re: [time-nuts] I love the smell of tantalum in the morning

Hi Tom, I'm a SMT rework technician for a large satcom and defense company. I have a shop at home too and all the equipment to repair this if I can be provided with the replacement cap. Please let me know if I can be of help. Chris KD4PBJ > On Nov 5, 2016, at 14:12, Tom Van Baak

Re: [time-nuts] I love the smell of tantalum in the morning

Hi A *lot* depends on how many planes there are in that board. The weight of he copper also maters a bit. If there is enough thermal mass, you will need a pre-heat process. There are lots of ways to do it ranging from the kitchen oven to various “frame and lightbulb” setups and on into ever

Re: [time-nuts] I love the smell of tantalum in the morning

So much information from so many that have obviously run into the smell of a burnt part. I do the cut the part to pieces and unsolder each leg. Also the 2 iron approach. The absolute goal, do not damage the board. I have a hot air station also and much like the comments made not impressed. I did

Re: [time-nuts] I love the smell of tantalum in the morning

Ok, thanks, Chris! Some day I'll learn SMT but I don't think it's wise for me to use a 5071 main board as my first mistake. So I'll follow-up with your generous offer off-list. /tvb - Original Message - From: Chris Waldrup To: Tom Van Baak ; Discussion of precise time and

[time-nuts] I love the smell of tantalum in the morning

Tom's method is what I use when replacing commodity parts that I don't care about salvaging. Much less chance of damaging anything. Hack the part apart, cut the leads on gull wing packages, etc. Don't waste your time with tweezers, lifting one end, etc. I have a very nice set of hot

Re: [time-nuts] Thinking outside the box a super reference

On 11/5/16 2:59 AM, Attila Kinali wrote: But we still need to ensure that the field is properly oriented and homogenous over the whole vapor cell. For this you need a cavity that is properly designed and most likely will be resonant at 6.9GHz. (I don't know whether it is possible to design a

Re: [time-nuts] Thinking outside the box a super reference

I think this is all described in the 1992 FCS papers, but the executive summary is that a direct synthesizer on 9192.63177 is to be avoided at all costs because of the danger of it leaking into the CBT cavity. This is also the reason why you don't multiply up a subharmonic of this frequency. It

Re: [time-nuts] Thinking outside the box a super reference

On 11/5/2016 12:18 AM, Poul-Henning Kamp wrote: In message <768ee5a7-1c53-06cf-cf36-ec75e2901...@karlquist.com>, "Richard (Rick) Karlquist" w rites: Reminds me of an interesting Jack Kusters story. There was some customer who was having problems with his atomic clocks being noisy

Re: [time-nuts] Thinking outside the box a super reference

Hoi Rick, On Sat, 5 Nov 2016 07:17:21 -0700 "Richard (Rick) Karlquist" wrote: > I think this is all described in the 1992 FCS papers, > but the executive summary is that a direct synthesizer > on 9192.63177 is to be avoided at all costs because > of the danger of it

Re: [time-nuts] I love the smell of tantalum in the morning

For through hole parts sure, but I would not recommend that on SMD parts, the copper foil of a little pad is pretty easy to tear off and it's a royal pain if you have to mount a device missing some of its landing pads. On Sat, Nov 5, 2016 at 4:37 PM, Tom Miller wrote:

Re: [time-nuts] Thermal impact on OCXO

Hi Scott, The 20 bits span about 6 volts.  The EFC range spans about 8Hz (+/-4Hz).  I don't do these calculations every day, but that's about 4.5PPT? Bob   - AE6RV.com GFS GPSDO list: groups.yahoo.com/neo/groups/GFS-GPSDOs/info

Re: [time-nuts] Thermal impact on OCXO

Hi Bob, Could you expound on "so far below a number of issues"? In any case, your post implies that something else is aging.  I'm using an ADR4533A as my voltage reference.  That feeds an AD8638 op-amp driving an MMBTA pass transistor.  That pretty much leaves the divider resistors on an

Re: [time-nuts] I love the smell of tantalum in the morning

Yes. Unless you're grinding it away with a dremel (which I wouldn't recommend as far as chemical dust is concerned), nibbling away with sidecutters would be trying to force the 2 ends of the component apart. That may be stressing the pads they're soldered to, leading to a possible pad lifting

Re: [time-nuts] Thermal impact on OCXO

If your DAC spans the full EFC range than 1LSB is 1/2^20 ~ 1 PPM of the EFC range, and the EFC tuning range is 8/10E6 ~ 1 PPM full scale, so 1 LSB is ~1PPT. So, if everything else is stable the DAC code reflects changes solely due to the OCXO, which would be an aging of 24 PPT/day. On Sat, Nov 5,

Re: [time-nuts] Thermal impact on OCXO

Hi If you go back to my previous list, all the things that have a tempco also age. Holding temperature over weeks or months is not at all easy …. You have gradients between parts so it is impossible to look at temperature (or aging) as a single effect. In the case of a fairly normal room,

Re: [time-nuts] Thermal impact on OCXO

Hi Scott, D'oh.  Thanks for the correction!  Like I said, I don't do these calculations often.  If as Bob Camp implies, the aging isn't from the OXCO, then I'm a bit stumped.  I do have an op-amp in the EFC string with  a voltage divider for gain.  The resistors are Panasonic ERA-6AEDxxxV

Re: [time-nuts] I love the smell of tantalum in the morning

On 11/05/2016 03:12 PM, Tom Van Baak wrote: > Having not done SMT before, how should I do it with minimal risk to the very > precious PCB. Or, what equipment should I use this as a good excuse to buy? Tom, I used the obvious but never read about using two soldering irons, invented it

Re: [time-nuts] Thermal impact on OCXO

...with a 20bit DAC, a suitable voltage reference for that DAC and an HP3458... On Sun, Nov 6, 2016 at 12:39 AM, Bob Stewart wrote: > Hi Hal, > > With a 20 bit DAC, even a small aging rate is going to show up. I'll let the > one GPSDO cook for a month or so and see what it

Re: [time-nuts] Lady Heather and LeapSecond

Where will the file go? -Original Message- From: Mark Sims To: time-nuts Sent: Fri, Nov 4, 2016 2:37 pm Subject: [time-nuts] Lady Heather and LeapSecond Yes, and it will also automatically do a screen dump to the file "leap_sec.gif" That all

Re: [time-nuts] Thermal impact on OCXO

Hi 2^20 is roughly 1 ppm. It is about 5 uV on a 5V line or 2.5 uV on a 2.5 V EFC center. A DAC that does 100 ppm / C is a pretty typical part. 10 ppm / C is unusually good A “good” voltage reference might do 2 ppm / C A very typical room will swing around +/- 2C without much

Re: [time-nuts] Thermal impact on OCXO

Hi Bob, But will any of the things you mentioned show up as a more or less linear march downhill at about 1 step per hour over the course of 7 days?  In fact, I think Dan's units show about the same -1 per hour, and he's had them running continuously for many months.  I believe you use these

Re: [time-nuts] Thermal impact on OCXO

I think that's a nice plot, it looks like you have stepped 160 LSB over 7 days or roughly 1 LSB per hour. With a 20bit dac you are trimming maybe 1 ppt/LSB to 4 ppt/LSB? In allan devation terms, the case of 1ppt/LSB, solely due to drift, you're at 1E-12 at 3600*sqrt(2) = 5000 s, in the case of

Re: [time-nuts] I love the smell of tantalum in the morning

metcal has a "hot twizer " to remove SMD components it heats the component on both end 73 Alex On 11/5/2016 12:55 PM, Hal Murray wrote: t...@leapsecond.com said: Having not done SMT before, how should I do it with minimal risk to the very precious PCB. Or, what equipment should I use this

Re: [time-nuts] I love the smell of tantalum in the morning

On Sat, 5 Nov 2016 20:57:11 +0100, you wrote: >> Having not done SMT before, how should I do it with minimal risk to the very >> precious PCB. Or, what equipment should I use this as a good excuse to buy? > >Now, for these caps, you can use a normal soldering-iron without too >much trouble, but

Re: [time-nuts] Thermal impact on OCXO

Hi Hal, With a 20 bit DAC, even a small aging rate is going to show up.  I'll let the one GPSDO cook for a month or so and see what it shows then.  I'll also pull the data from the log file and see if I can see any correlation between the temperature and the EFC over time.  IOW, for data

Re: [time-nuts] Newbie With a Z3801 Problem

Am 05.11.2016 um 12:51 schrieb Bill Riches: Hi Mark, Thank you for working with the KS24361. Looking forward to when the program will be available. Any ideas on being able to use the 1 PPS signal out of the KS24361 to drive SL sound card calibration? It is a weird pulse and someone

Re: [time-nuts] Thermal impact on OCXO

This seems to be turning into a rabbit hole from which there can be no possible return.  With no evidence, you question my competence and cast aspersions on my testing methodology.  I give up.  Have a nice day. Bob - AE6RV.com

[time-nuts] Corby Watson Super 5065a work can I use a miniature Rubidium

Hi all,a few day ago I read "super HP5065A" from Mr Corby and I wondering if any one has done same thing with "telecom" Rubidium pack ? I found an optical bandpass filter cost is cheap enough to a third country people like me but if any one has tried before and know a lot more than what I know

[time-nuts] Lady Heather and LeapSecond

It should wind up in the standard Lady Heather directory... depends upon the operating system and how the program was started. From the keyboard in Lady Heather, type ? That will bring up the command line option help. Scroll/page down to the end of the info and there will be a line that

Re: [time-nuts] Thinking outside the box a super reference

On Fri, 04 Nov 2016 23:04:22 + "Poul-Henning Kamp" wrote: > First: Yes, but if you pick a sensible vibration mode for your > microwave resonance, that can be done with an screw-in endcap. > > Second: No, I would actually not need to tune it. > > Historically

Re: [time-nuts] Thinking outside the box a super reference

Am 05.11.2016 um 00:45 schrieb David: On Fri, 04 Nov 2016 14:39:54 -0700, you wrote: 87-Rb has a half life of something like 4.9e10 years — you'll be waiting a while for that strontium. /gp Various online sources say that natural rubidium is radioactive enough to fog photographic film in 1 to