Rubidium Standard

[bsalai]

I bought a rubidium standard a while ago, but just got around to hooking it up. I'm wondering if what I'm seeing is normal.
Initially, it drew about an amp and a half but relatively quickly dropped to about .7 amp, all at 24 V. It is quite warm. You can touch it, but wouldn't want to leave your fingers on it.
It seems to be pretty stable after about half an hour. It reads 9.99999927 on my HP 5335A counter that has an oven controlled oscillator but has not been calibrated in who knows how long. I've been watching it for a while, about 45 minutes minutes, and the last digit was initially changing from 7 to 9 and back pretty slowly but seems to have stabilized at 8. If I'm counting digits right, that's tenths of a cycle. The current is coming down slowly. It started out (after the initial warm up at 1.6A) at about .7 A and is now down to .53 and seems to have stabilized there.
I'm seeing about .8 V out into 50 ohms, and just over 2 V into a one meg load.
If anyone else has one of these running, I'd be interested in whether this is consistent with what you see.
Finally, I'd like to build an amplifier/buffer to drive four outputs at about a volt for the other instruments here that can accept an external reference. Does anyone have any pointers to an appropriate circuit?
Thanks,
Brad



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[Gyro]

There has been lots of activity on the forum on the subject in the past, not in the last month or so that I remember, but a forum search for Rubidium will pull up lots of threads, teardowns, repairs etc.

It is normal for them to pull more current at startup (temperature stabilisers) and to run hot - I think most like to be heatsinked for a decent operating life!


P.S. Several people have modified Video distribution amps (modified for 50R) for distribution purposes.

[NivagSwerdna]

I used a LT6551 for a 4-way distribution... works pretty well.

https://www.eevblog.com/forum/projects/a-look-at-my-symmetricom-gpsdo-(ocxo-furuno-receiver)/msg947866/#msg947866

And yes... very large start-up current until it's all warm and toasty.

[edpalmer42]

We could give you more specific info and/or links if you told us the make and model of your unit.

Ed

[bsalai]

The only number I can read is XHTF1003H.
I'll try to take a picture of the label.


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[bsalai]

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[edpalmer42]

I haven't seen any discussions on that model.  There might be something on some Chinese language boards.  It appears to be a Chinese clone of the LPRO, but it apparently has some form of RS-232 communications which the LPRO didn't have.  You're kind of on your own here, although info on the LPRO might be at least partially applicable.  Maybe edit the Subject of this thread to include the model number and see if you can find some others who have that model.  This could become the main source of info on this model.

Ed

[bsalai]

I tried to edit the title but it said I'm not allowed to move my posts??

I wonder if anyone can translate the descriptions of pins 3, 6, and 7? I'm pretty sure the other three 2, 4, and 9 are grounds.


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[NivagSwerdna]

Same as ?

[bsalai]

Yea


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[bsalai]

 Yes


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[edpalmer42]

I tried to edit the title but it said I'm not allowed to move my posts??

I wonder if anyone can translate the descriptions of pins 3, 6, and 7? I'm pretty sure the other three 2, 4, and 9 are grounds.


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I'm sure I've seen people edit the subject, but I've never tried it.

Are you sure about pin 9?  To be compatible with the LPRO, pin 8 should be ground, but not 9.

Regarding translation, it's possible to do it online, but you need a better picture than the one you posted.  First you have to do OCR to convert the picture into text.  Then you translate the text with Bing or Google.  Then you try and figure out what the heck the English means. 

Ed

[bsalai]

You're right, 2, 4, and 8 are ground. 5 and 9 are RS232.


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[bsalai]

Except for figuring out what the RS232 port does, and building a 4 port driver, it seems to be working fine. It would be nice to understand it more completely though.


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[Ash]

Hi,

I have one of these Rubidium oscillators as well. I'm planning on setting it up in a box with a small distribution amp etc.. From memory the original seller (it was a while ago) stated it was compatible with the LPro-101 (http://www.ham-radio.com/sbms/LPRO-101.pdf). Interestingly its not a direct copy inside..

I've used mine a few times to calibrate stuff I've repaired (spectrum analyser etc).

I translated the label on mine using the Google translate app on my phone..

Model: XHTF1003H
Number: 1 314205
Date: 201312
Chengdu Tianao Electronics Co., Ltd.

1 - 10MHz RF output
2 - 2 RF ground
3 - light instructions (lamp voltage??)
4 - chassis ground
5 - RS232 RXD
6 - 6 lock indication
7 - external frequency ESC (external frequency adjustment??)
8 - power ground
9 - RS232 TXD
10 -  + 24V power supply

The LPRO manual gives the following pinout.

1 RF OUT 470 pF PI - FILTER
2 CHASSIS GND SHORTING PIN
3 RF RTN (CHASSIS GND) 470 pF PI - FILTER
4 CHASSIS GND SHORTING PIN
5 LAMP VOLTS 1000 pF PI - FILTER
6 BITE* OUTPUT 1000 pF PI - FILTER
7 EXT. C-FIELD VOLTAGE ADJ. 1000 pF PI - FILTER
8 +24V RTN 1000 pF PI - FILTER
9 CRYSTAL VOLTS MONITOR 1000 pF PI - FILTER
10 POWER +24V 1000 pF PI - FILTER
* Built-In Test Equipment (unlock indicator)

So its probably not identical.. But close enough to get it working.

Cheers,
Ash.

[Dr. Frank]

..

. It is quite warm. You can touch it, but wouldn't want to leave your fingers on it.

Thanks,
Brad

Brad,

don't forget to assemble the unit on a big heat sink, like a metal sheet.
The interior ovens get hot to 76°C and 106°C, so the electronics MUST be cooled, otherwise will die soon.
It's necessary to limit the baseplates temperature to max. 65°C.

Frank

[bsalai]

Frank,

Thanks, I'll do that.

Brad


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[bsalai]

I've mounted a large heat sink to the base of the standard, and I"m letting it warm up to see how hot it gets. so far, about 10 minutes, it is warm, but no longer uncomfortable to touch. I don't have an easy way to measure the temp, maybe I"ll try my meat fork. I did, and after about half an hour it reads 43 C

Meanwhile, I've been monitoring the frequency with an HP 5335A counter, and the counter and the standard either drift at the same rate, or both are relatively stable. The reading is the same as it was the last time I powered the standard up a week ago, 9.999 999 28, and doesn't seem to be moving at all.

My question is, since the OCXO in the counter seems to have good short term stability, and perhaps long term as well, would it make sense to adjust it to 10.000 000 00?
If so, I looked at the documentation I have and didn't see a procedure for doing this, has anyone done it? If so, how?

I do recognize that this is a very small change, and adjusting it may be a bit silly.

Thanks all for the info and encouragement.

Brad

[Vtile]

I've mounted a large heat sink to the base of the standard, and I"m letting it warm up to see how hot it gets. so far, about 10 minutes, it is warm, but no longer uncomfortable to touch. I don't have an easy way to measure the temp, maybe I"ll try my meat fork. I did, and after about half an hour it reads 43 C

You need to get a few LM35 or LM234-x chips or something passive (thermocouple or PT100(0) ). 

[Dr. Frank]

I've mounted a large heat sink to the base of the standard, and I"m letting it warm up to see how hot it gets. so far, about 10 minutes, it is warm, but no longer uncomfortable to touch. I don't have an easy way to measure the temp, maybe I"ll try my meat fork. I did, and after about half an hour it reads 43 C

Meanwhile, I've been monitoring the frequency with an HP 5335A counter, and the counter and the standard either drift at the same rate, or both are relatively stable. The reading is the same as it was the last time I powered the standard up a week ago, 9.999 999 28, and doesn't seem to be moving at all.

My question is, since the OCXO in the counter seems to have good short term stability, and perhaps long term as well, would it make sense to adjust it to 10.000 000 00?
If so, I looked at the documentation I have and didn't see a procedure for doing this, has anyone done it? If so, how?

I do recognize that this is a very small change, and adjusting it may be a bit silly.

Thanks all for the info and encouragement.

Brad

Well done, the cooling, and also the measurement of the temperature!
The adjustment of the OCXOs frequency might make sense, as the Rb clock might be closer to 10MHz, as it drifts less.

Myself, having several HP OCXOs (i.e. 10811A-60111 in the 5335A and the 5370B), these have typical stability of around 10^-9, over many months, after all these years.
You can trim these OCXO to a bit better than that level, i.e. a few parts in 10^-10, provided, you always leave the 5335A plugged in, so that the single red LED is illuminated.

Your 7.2*10^-8 deviation is about 2 orders of magnitude bigger than what these OCXOs are capable of, so it makes sense to trim. (The "but" comes later.)

It's easy to adjust the OCXO to the same frequency as the Rb standard.
Simply apply the 10MHz from the Rb to the A - input of the 5335A, choose longest possible Gate Time, about 4 sec, and measure the frequency.
Open the lid of the counter, and adjust the OCXOs frequency, so that the counter reads exactly 10.000 000 00 MHz.

The 5335A resolves about 1..2ns / sec Gate Time, so it has at least 10^-9 resolution @ 4 sec Gate Time.

I made a modification on my counter to have 12.5 sec Gate Time on the front potentiometer, so my 5335A displays 10 digits.

Anyhow, if you have GPIB capability, you may also use Time Lab, a freeware program by ke5fx: http://www.ke5fx.com/timelab/readme.htm
It allows you, by means of the 5335A itself,  to measure the Allan Deviation of your OCXO vs. the Rb, and also to make precise adjustment of the OCXO in the frequency deviation measurement mode.

Here comes the "but": The basic problem, whether your Rb standard is still precise enough, you can solve only by taking the next step, that is acquiring a GPSDO receiver, and adjusting the Rb standard to < 10^-11.
May the Lady Heather be with you!

Frank

[NivagSwerdna]

I've mounted a large heat sink to the base of the standard, and I"m letting it warm up to see how hot it gets. so far, about 10 minutes, it is warm, but no longer uncomfortable to touch. I don't have an easy way to measure the temp, maybe I"ll try my meat fork. I did, and after about half an hour it reads 43 C

Quick question.... Why?  Isn't the oven meant to run hot so adding extra heat dissipation just makes it work harder? I can see that adding thermal mass might help stability but a heat sink?

[CJay]

No, they have optimum working temperatures like all components, they need a heatsink to keep them within that range and the oven is rated for that.

Running them without cooling can drastically shorten their lifespan, if you trawl back through the discussions of this on the timenuts mailing list it can be down to a few months instead of several years.

[NivagSwerdna]

Running them without cooling can drastically shorten their lifespan, if you trawl back through the discussions of this on the timenuts mailing list it can be down to a few months instead of several years.

I am highly skeptical.... but.... a bit of googling on my FE-5680A would suggest a dissipation of around 11W... hence mounting on a panel.

[Gyro]

Why the skepticism?

The unit contains standard PCB mounted components, including electrolytics. It also contains oven, Rb chamber, lamp etc. that run at higher fixed temperatures. If you don't heatsink the outer enclosure properly then the latter will cook the former.

All ovens need a certain amount of heat drain anyway in order to maintain regulation.

[CJay]

Running them without cooling can drastically shorten their lifespan, if you trawl back through the discussions of this on the timenuts mailing list it can be down to a few months instead of several years.

I am highly skeptical.... but.... a bit of googling on my FE-5680A would suggest a dissipation of around 11W... hence mounting on a panel.

I was of the same opinion as you initially, didn't seem to make sense, but the two FE devices I have are/were on heatsinks from the integrator so I'm inclined to believe the hive mind.

The FE-5660 I have is in a Tait T801 Frequency reference and is on a whopper of a cast alloy heatsink, the Fe-5680, when you see pics of the mounted, are always on some sort of thermal solution even if it's not a proper heatsink. I'm fairly certain I've seen advice from FE saying they should be as well, maybe in the FE-5680 technical reference?

[bsalai]

The case has six threaded holes for mounting, two rows of three set in from the edges. They seem to be intended to mount to some sort of plate, consistent with a heat sink. The surface isn't flat, so I've ordered a sheet of material to better couple to the heat sink. It is still quite warm, I'm inclined to agree with CJay that the heat sink protects the rest of the components.


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[bsalai]

Well, I set the counter internal reference to the rubidium standard, but have no way to tell how accurate it is. All those zeros do look impressive though. Reminds one of the difference between precision and accuracy.
I also hooked an led to the lock output, which goes low when locked. The led is on dimly while warming up which is odd. The transition is clear though, and corresponds to the time when the frequency stops hunting.
Since the OCXO is so stabile, I'm questioning the need to actually use the standard continuously. Maybe powering it up from time to time to verify the counter accuracy would prolong its life. I can use the counter's reference output for the signal generator reference input. All of this is primarily interesting rather than useful to me, but it is fun and educational.
Thanks for all the help here.
Brad


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[Dr. Frank]

That grey-haired guy in the back, that is you?
So everything looks alike in my lab, 5335A, 3325B, Rb standard.. and a lot other time-nuts stuff.

Well, the OCXO seems to be adjusted very well, I assume, you did NOT attach the Rb also to the 5335As REF IN?

1E-9 is a reasonable precision for the OCXO.
If you want to get deeper into stability figures, I really recommend to try the Time-Lab, it's really fun to dig into Allans Deviations.

An OCXO needs 48h to stabilize to a stable frequency, i.e. < 1E-9. So it should be powered on all the time, as it's the case of our 5335As. Consumes a few Watts, which I can afford, even here in Germany.

Rb clocks may need up to 5 days, to stabilize to about parts in  1E-11, so it's not recommended to switch it on for a quick measurement only.

You may also let it run, and feed to REF IN of your 5335A.
That would be the most stable oscillator for this counter.

P.S.: The back plane cooling of the Rb standard is definitely necessary.
Please trust an experienced time-nuts, or read the manuals of the LPR-101, or the EFRATOM FRS-K.
These specify the use of a metal plate, to limit the temperature.
In the LPRO manual, the MTBF figures go down drastically with rising temperature, and in the FRS-K manual, 65°C back plane temperature is defined as absolute maximum.

The 2nd effect after the limitation of the life time, is the stability of the internal ovens, which might be affected, or unregulated, if improper cooling lets the internal temperature rise above the 70°C of the first oven in the physics package.

Frank

[bsalai]

It is me, I hadn't noticed. My "lab" was a very small yoga room, hence the mirrored wall behind the shelves.
The counter is plugged in continuously. I had to unplug it briefly to pull it out to get at the OCXO adjustment. Probably less than 30 seconds. I let it run until the displayed frequency of the rubidium standard stabilized at the same frequency as it saw when it had run continuously for weeks. That only took a few minutes, probably because the oven had barely cooled.
Here are a couple of pictures of the heat sink

The coupling to the surface of the rubidium standard isn't great, but when I get the thermally conductive pad that I ordered it should be much improved. At that point I'll turn the standard on and leave it for a couple of weeks to stabilize and then repeat the measurement.
The other problem is that the heat sink won't fit in the aluminum box I'd hoped to use. I'll have to mount the standard inside and the heat sink outside. That seems sub optimum since I'd expect the inside of the box to heat up. I hate the thought of a fan running constantly to cool the inside of the box. If I can find a rack panel to hold everything that might be the answer.
Thanks again for the help.
Brad



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[Dr. Frank]

The coupling to the surface of the rubidium standard isn't great, but when I get the thermally conductive pad that I ordered it should be much improved. At that point I'll turn the standard on and leave it for a couple of weeks to stabilize and then repeat the measurement.
The other problem is that the heat sink won't fit in the aluminum box I'd hoped to use. I'll have to mount the standard inside and the heat sink outside. That seems sub optimum since I'd expect the inside of the box to heat up. I hate the thought of a fan running constantly to cool the inside of the box. If I can find a rack panel to hold everything that might be the answer.
Thanks again for the help.
Brad

Such a big heat sink is not needed, see the hints in the manuals I mentioned.
I have assembled the Rb clock to the bottom metal plate inside a rack size enclosure, using thermal paste, and that's sufficient.
I assume, that the Rb clock should not be used upside down, due to thermal flow.

You won't see any difference on 1E-9 level, between the OCXO and the Rb clock.
The Rb is about 100 times more stable (1E-11) than the OCXO, so that's also the order of magnitude, where you would see any difference over a weeks time.. if you would compare it to a GPSDO, or a Cs clock.

Frank

Frank

[bsalai]

 This is a slight change of topic. 

I connected the 10MHz out from the 5335A counter to the reference in on the 3325A function generator. I set the function generator to 1000 Hz ant connected its output to the A input of the counter. After warming up for several hours I get this




The last three digits vary +- .150 Hz or so.
I recognize that this is a very small change, but wonder what is causing it since the two Instruments are using the same frequency standard. Mostly curiosity on my part.

Brad


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[Dr. Frank]

The 3325A/B uses an M/N counter locked PLL.
So lower frequencies are less stable than those being closer to 30MHz, which is its internal master clock.
Try that measurement at 1 MHz or 10MHz, and you'll see stabilities to 1E-9, or better (with higher resolving counters, like the 5370B).

I have measured the Allan Deviation for different output frequencies, and at 1kHz, red curve, it's on the order of about 1E-7 only, depending on the Gate Time.
So that's the 3325As deviation / fluctuation, which  your counter detects also.



This stability parameter / Allan Deviation is NOT specified in the manual, it's a real gap, for some reason. (i.e. principle of operation of the synthesizer).

I always wanted to ask the time-nut community, whether this is all correct, but now I really believe so.

Frank

P.S.: once again, I recommend Time-Lab, which allows to acquire such Allan Deviation measurements.

[bsalai]

Frank,
I've started looking at options for GPIB. There are GPIB-USB converters that seem convenient but are expensive. There are also various adapters/cards that seem to be less expensive. NI has drivers, but it isn't clear whether they are free.
What are you using? Any suggestions?

Brad


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[Dr. Frank]

I can't give you an advise, as I'm having standard GPIB cards from N.I.
Time-Lab also works with USB/GPIB adapters, afaik, but please check in the description.
Which cheap adapter to buy, I don't know-there have been many hints somewhere else here in the forum.

Frank

PS: Obviously, Prologix GPIB/LAN adapter is supported, at least.

[HighVoltage]

I am also looking for a Rubidium standard but there are so many on ebay it is difficult to select one over the other.

This one looks nice:
10MHZ Efratom Rubidium FREQUENCY Standard FRS-C , Square-wave,output high level
http://www.ebay.com/itm/10MHZ-Efratom-Rubidium-FREQUENCY-Standard-FRS-C-Square-wave-output-high-level-/281450872886?hash=item4187c78036:m:mr2dt-0VVev04AkzL_2GF8w

But I have no idea how it compares in a real world to others
Any suggestions of which one to get?

[bsalai]

Mine outputs a sine wave. I am not sure, but a square wave could be better in some applications, but it will be rich in odd harmonics.


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[bsalai]

Also, the prices are at least double what I paid less than a year ago.

Depending on what you are trying to do, my experience with the OCXO in my counter showed it to be accurate to less than one Hertz at 10 MHz, and quite stable at least in the short term. For me, that is probably good enough but I don't regret getting the rubidium standard if only for the experience. Dr. Frank is very knowledgeable and helpful.


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[0.01C]

I am also looking for a Rubidium standard but there are so many on ebay it is difficult to select one over the other.

This one looks nice:
10MHZ Efratom Rubidium FREQUENCY Standard FRS-C , Square-wave,output high level
http://www.ebay.com/itm/10MHZ-Efratom-Rubidium-FREQUENCY-Standard-FRS-C-Square-wave-output-high-level-/281450872886?hash=item4187c78036:m:mr2dt-0VVev04AkzL_2GF8w

But I have no idea how it compares in a real world to others
Any suggestions of which one to get?

some RB seller is from China ,you can find many used rb less then $100 in https://world.taobao.com

https://s.taobao.com/search?q=%E9%93%B7%E9%92%9F&type=p&tmhkh5=&spm=a21wu.241046-hk.a2227oh.d100&from=sea_1_suggest&catId=100

[CJay]

some RB seller is from China ,you can find many used rb less then $100 in https://world.taobao.com

https://s.taobao.com/search?q=%E9%93%B7%E9%92%9F&type=p&tmhkh5=&spm=a21wu.241046-hk.a2227oh.d100&from=sea_1_suggest&catId=100

Is it possible to buy from TaoBao oiutside of China, I can't find an English version of that page

[0.01C]

some RB seller is from China ,you can find many used rb less then $100 in https://world.taobao.com

https://s.taobao.com/search?q=%E9%93%B7%E9%92%9F&type=p&tmhkh5=&spm=a21wu.241046-hk.a2227oh.d100&from=sea_1_suggest&catId=100

Is it possible to buy from TaoBao oiutside of China, I can't find an English version of that page

yes ,you can buy from taobao and ship the item to UK  .but you need to contact seller for the shipping ,
use google translate.

[TheSteve]

I am also looking for a Rubidium standard but there are so many on ebay it is difficult to select one over the other.

This one looks nice:
10MHZ Efratom Rubidium FREQUENCY Standard FRS-C , Square-wave,output high level
http://www.ebay.com/itm/10MHZ-Efratom-Rubidium-FREQUENCY-Standard-FRS-C-Square-wave-output-high-level-/281450872886?hash=item4187c78036:m:mr2dt-0VVev04AkzL_2GF8w

But I have no idea how it compares in a real world to others
Any suggestions of which one to get?

You might consider contacting user "yixunhk" on ebay and asking if he has anymore broken LPFRS-01 units. Late 2015 a bunch of us bought them in 5 packs from him for 129 USD + shipping. I was able to get all of mine working great with new electrolytics and the odd tweak to a pot or two. I know you like repairing stuff.    I run one 24/7 and am very impressed every time I compare it to my GPSDO. Most of the time I'd rather use it to feed my dist amp instead of the GPSDO as there is no externally mounted antenna to attract static or worse lightning.

[Dr. Frank]

I am also looking for a Rubidium standard but there are so many on ebay it is difficult to select one over the other.

This one looks nice:
10MHZ Efratom Rubidium FREQUENCY Standard FRS-C , Square-wave,output high level
http://www.ebay.com/itm/10MHZ-Efratom-Rubidium-FREQUENCY-Standard-FRS-C-Square-wave-output-high-level-/281450872886?hash=item4187c78036:m:mr2dt-0VVev04AkzL_2GF8w

But I have no idea how it compares in a real world to others
Any suggestions of which one to get?

There are several comparisons by well-known time-nuts:

http://www.ke5fx.com/rb.htm
http://febo.com/pages/oscillators/rubes/

The FE5680A is not so good in terms of phase noise, then comes the FRS, then the LPRO-101, but they all perform similar in respect to stability.
No wonder, as the underlying physical principle and practical setup is identical.

The Stanford Research PRS10 is the best performer, but expensive.

The most important questions, anyhow, is the life expectancy, as all of the surplus devices made many years already in telecommunication cells.

I think, the FRS might be older than the LPO, so maybe you find a seller who publishes the lamp voltage, to estimate the time-span left.

There are also ways to rejuvenate the Rb cell, instructions for that can be found.

I have an old EFRATOM FRS-C (I think), which works ok.
Manual for these units is the best, very detailed.
output can be changed from sine to square and vv.

Frank

[0xPIT]

Hey,

does anyone happen to have any information as to what can be done with the Serial Port on the XHTF1003H by Chengdu Tianao Electronics Co., Ltd., and how the protocol works?
I've emailed the company several times, but with no success at all.

I'm attaching the data sheet I've found for the box.

Thanks

 - pit

[pelule]

I remember, I have read somewhere in the web, you can set the frequence output (divider).
But unfortunately I can't remember, where I have read it.
/PeLuLe

[Tony_G]

I've started looking at options for GPIB. There are GPIB-USB converters that seem convenient but are expensive. There are also various adapters/cards that seem to be less expensive. NI has drivers, but it isn't clear whether they are free.
What are you using? Any suggestions?

I use an E5810A that I bought from EBay - It's a LAN to GPIB adapter and is supported by the current Keysight IO Libraries Suite. If you wanted to save some money you can get the previous one, E2050A for around US$100.

Personally I like these because I can use any network connected PC in my house, including my tablets, to run control software. I also have a Prologix GPIB-LAN, an Agilent 82357B and an old HP 82341C - I prefer the 5810 over all of them.

There are also many many fakes of the 82357B on EBay that seem to work fine - I've also seen an increase in the NI USB adapters so I suspect those are fakes as well.

Lastly, if you have a proper desktop then there are many PCI GPIB adapters (though the PCI-E adapters seem wildly overpriced).

As an aside, I wouldn't trust anything from China that says "New sealed box" as there are many videos showing that they've cloned the packaging as well.

TonyG

TonyG

[bsalai]

I don't have the software skill to do this, but it seems like the new ESP-32 could be the basis for a GPIB – Wi-Fi adapter. I think it has enough I/O pins on board that all you would need would be a power supply, a few pull up/pull down resistors, a connector, and a housing. The connector and the housing would probably be the most expensive parts. I think the total cost would be less than a good quality cable.
The software would take some effort, but I think there is arduino/8266 software out there that would be at least a good start.

Am I missing something.


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[Tony_G]

This thread has details on building a GPIB adapter using an Arduino if you're looking for that

https://www.eevblog.com/forum/testgear/gpib-interface-(ieee488)/

TonyG

[alm]

Am I missing something.

IEEE 488.1-compliant bus drivers? See the thread linked by Tony_G for some discussion.

[bsalai]

I had read that. My thought was that the 8266 didn't have enough I/O pins so the Arduino was required. The ESP32 has more pins and runs Arduino code. It can do BLE and wifi.
Could you do a wifi - GPIB adapter with just that one chip?
Doesn't some of the control software work with the existing wifi adapters that cost about $200?


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[texaspyro]

Here is some C code that I wrote for doing GPIB on an AVR chip (2561).  It emulates the Prologix GPIB-serial adapter (with some extensions).   Released under the MIT license.  Tested with gpibkit.

Note that the attached code is not complete (it uses LCD/touchscreen/serial I/O routines and some header files that are not included),   but should be fairly easy to modify for other systems.  The serial I/O routines are interrupt driven and use buffered I/O.

You can find the missing code here:

https://github.com/mega-donkey/Mega-Donkey

The file also has code for emulating another GPIB serial interface...  it should be nuked from orbit.

[texaspyro]

does anyone happen to have any information as to what can be done with the Serial Port on the XHTF1003H by Chengdu Tianao Electronics Co., Ltd., and how the protocol works?

My bet is the serial protocol is the same as the LPFRS.  Serial 1200,8,N,1  On the LPFRS the serial port is TTL level RS-232 (not inverted TTL "UART" polarity).  You can connect it directly to most serial ports. 

Pin 9 goes to RS-232 pin 2  and pin 5 goes to RS-232 pin 3.  Try sending it a "M" or "V"  There are also commands for setting the freq.  Coarse freq is done by a DDS and fine freq is done with the C-field current. 

Lady Heather v6 will be able to talk LPFRS.  Attached is a plot of an LPFRS powering up.


http://www.spectratime.com/documents/lpfrs_manual1.pdf

[Johnny10]

I just purchased an Efratom Rubidium Oscillator CTS-101

Is there pinout data available?

Would like to make a distribution box for this unit.

[edpalmer42]

I just purchased an Efratom Rubidium Oscillator CTS-101

Is there pinout data available?

Would like to make a distribution box for this unit.

A google search doesn't turn up much.  There's likely a more common Rb standard inside the box.  You may have to dump the box and just work with the Rb standard itself.  That J3 connector by itself will likely cost $30 - $50.  J2 is almost as bad, although it's the same connector that's on the FRK Rb standard so you might luck out and find that it's the same pinout.

When you get the unit, start a new thread instead of adding on to this one.

Ed

[awallin]

I just purchased an Efratom Rubidium Oscillator CTS-101

these might help, but no manual for that particular model number...
http://www.ko4bb.com/getsimple/index.php?id=manuals&dir=02_GPS_Timing/Efratom

[Johnny10]

I feel like such a dummy.

Took apart the CTS-101 case and inside...

FRS-C 10MHz which I had no problem finding the manual for.

[edpalmer42]

Is there anything else in there that looks interesting?  Those external connectors suggest that there should be other functions in the box.  By the way, the connector that plugs into the FRS is also quite expensive to buy so be sure to salvage it.

Ed

[Johnny10]

Just one board.

[Johnny10]

After a bit more research I see someone asked time-nuts back in 2005 Board 55761

[time-nuts] Unknown Efratom 10MHz Assy, information asked

answered:
The board you are describing is used in the Lucent RFG-M-XO reference
frequency generator. It takes in 10 MHz on J2 from a Rubidium oscillator and
disciplines the Efratom SC cut OCXO on the main board from the 10 MHz input.
The output from the OCXO is converted to 15 MHz and supplied as the
reference output on J4.
The RFG-M-RB and RFG-M-XO normally mount together in a chassis



Well Maybe

[edpalmer42]

You can research the Lucent RFG equipment.  There's a fair amount of info around on it.  But I don't remember seeing a board that has that large connector on it.  It doesn't appear to have any smarts so it's just buffering, splitting, multiplying, maybe dividing.  Looks like at least one output is 20 MHz differential on the large connector.  I suspect that it will be a write-off.

Ed

[Johnny10]

I've been looking at manuals for some of the Efratom Portable Frequency Standards manuals.
I am beginning to think this board supplied the RS-232 input to FRS-C, and that J3 connector provided 1,5,10MHz TTL output, 5MHz Sine output and board connector provided 10MHz Sine.

Most units had a 24V Lambda Power Supply.
Just need to Find pinout for J2 to test that idea.
I already know from the Label the pinout for J1.

Front panels for the Portable Frequency Standards also had power on and frequency lock LED's.
And sometimes frequency adjust pots.

[Johnny10]

Got the board partially working with the Rubidium Oscillator.
Puts out 3 nice 10MHz sine waves from the J-3 connector and a pretty ugly 60Hz.