Author Topic: Economical option for precision frequency reference?  (Read 121981 times)

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Offline George_Race

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Re: Economical option for precision frequency reference?
« Reply #25 on: July 19, 2015, 01:25:53 am »
Not sure what reasonable price is to you, but for $250 you can have a primary standard in your shop.
For several years I have been using a Trimble Thunderbolt GPS.  I have it driving the 10 MHz external standard input of 2 frequency counters, my HP Signal Generator, My HP Spectrum Analyzer, and other stuff on my work bench.
And this is considered a PRIMARY STANDARD!  Precise frequency generation and measurements can be made to .01 Hz time and time again.

Here is a complete unit, including a 10 MHz distribution amplifier for $250!
Click on the link below:
http://www.ebay.com/itm/TRIMBLE-GPS-RECEIVER-THUNDERBOLT-KIT-DISTRIBUTION-AMP-/291515708632?pt=LH_DefaultDomain_0&hash=item43dfb0b4d8

There is a lot of information on the web concerning the use of the Trimble Thunderbolt as a primary standard.   Do some searching and a lot of info will pop up.
If you are interested, I can send a lot more information on what I put together to get the job done.
Hope this helps,
George - WB8BGY

Look at the bottom picture on this page.  It shows my Trimble Thunderbolt information.  Running the Lady Heather program on an old laptop.

http://www.mrrace.com/product_pages/other_items/MyTestBench/index.htm

73...George
« Last Edit: July 19, 2015, 01:42:05 am by George_Race »
 

Offline Shock

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Re: Economical option for precision frequency reference?
« Reply #26 on: July 19, 2015, 05:12:38 pm »
However, due to a happy coincidence, there is another option.

Thanks for the heads up on the Lucent/Symmetricom, I pulled the trigger and now am in GPSDO land.
Soldering/Rework: Pace ADS200, Pace MBT350
Multimeters: Fluke 87V, 117, 27/FM       >>> WANTED STUFF <<<
Oszilloskopen: Lecroy 9314, Phillips PM3065, Tektronix 2215a, 314
 

Offline N8AUM

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Re: Economical option for precision frequency reference?
« Reply #27 on: July 19, 2015, 05:48:35 pm »
Crap, wish I didnt see the Lucent/Symmetricom but for that price I had to pull the trigger to  |O
 

Offline Shock

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Re: Economical option for precision frequency reference?
« Reply #28 on: July 19, 2015, 06:20:27 pm »
Just been reading up on them quite interesting. I thought what no 10MHz! Then I realized they were talking about the GPS receiver which has 10MHz on the PCB, just no external connector. $100 for 5, 10 and 15MHz, 1pps, time/date, redundancy, interface. What more could you ask for?

You could probably go around to a friends place leave him the redundant unit working then go home and use the receiver.

http://www.febo.com/pipermail/time-nuts/2014-October/087274.html
« Last Edit: July 19, 2015, 06:25:13 pm by Shock »
Soldering/Rework: Pace ADS200, Pace MBT350
Multimeters: Fluke 87V, 117, 27/FM       >>> WANTED STUFF <<<
Oszilloskopen: Lecroy 9314, Phillips PM3065, Tektronix 2215a, 314
 

Offline PaulAm

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Re: Economical option for precision frequency reference?
« Reply #29 on: July 19, 2015, 07:51:54 pm »
I just picked up a NOS Lucent timing antenna with mount for $30.  Now waiting for an N/F adapter so I can put it on the roof.  Still have to throw a power supply together and gut an ancient UPS in a half rack cabinet to put it in.
 

Offline N8AUM

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Re: Economical option for precision frequency reference?
« Reply #30 on: July 20, 2015, 04:15:19 pm »
I just picked up a NOS Lucent timing antenna with mount for $30.  Now waiting for an N/F adapter so I can put it on the roof.  Still have to throw a power supply together and gut an ancient UPS in a half rack cabinet to put it in.

Think I have a similar one that came with my Nortel Trimble NTGS50AA unit. Dont notice much difference in performance between it and the el-cheapo $5 Chinese ones.

73 
 

Offline motocoder

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Re: Economical option for precision frequency reference?
« Reply #31 on: July 20, 2015, 05:14:33 pm »
Just been reading up on them quite interesting. I thought what no 10MHz! Then I realized they were talking about the GPS receiver which has 10MHz on the PCB, just no external connector. $100 for 5, 10 and 15MHz, 1pps, time/date, redundancy, interface. What more could you ask for?

You could probably go around to a friends place leave him the redundant unit working then go home and use the receiver.

http://www.febo.com/pipermail/time-nuts/2014-October/087274.html

Yes, it seems like a great deal. Mine arrived on Saturday. I ordered the wrong cable (got a RP-TNC instead of TNC, and I need to rig up some sort of a DB9 connector for power), so I wasn't able to hook it up. However, looking at the construction of this thing, it is obviously a serious quality piece of gear.

Looking forward to getting it running this weekend.
 

Offline N8AUM

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Re: Economical option for precision frequency reference?
« Reply #32 on: July 20, 2015, 07:48:45 pm »
Just been reading up on them quite interesting. I thought what no 10MHz! Then I realized they were talking about the GPS receiver which has 10MHz on the PCB, just no external connector. $100 for 5, 10 and 15MHz, 1pps, time/date, redundancy, interface. What more could you ask for?

You could probably go around to a friends place leave him the redundant unit working then go home and use the receiver.

http://www.febo.com/pipermail/time-nuts/2014-October/087274.html

Yes, it seems like a great deal. Mine arrived on Saturday. I ordered the wrong cable (got a RP-TNC instead of TNC, and I need to rig up some sort of a DB9 connector for power), so I wasn't able to hook it up. However, looking at the construction of this thing, it is obviously a serious quality piece of gear.

Looking forward to getting it running this weekend.

Isn't J1 the 10Mhz out pictured on the bottom unit ?
I tried looking for more info info on these units and suspect thats why they are cheap because theres practically NO information on these units  :scared:
I think I read in that one article that the power goes straight into a DC/DC converter so thats where I am going to feed mine.
Looks like your the 1st kid on the block with one of these old-timers so PLEASE keep us posted with your finding. 

73
Good luck ! 
 

Offline dadler

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Re: Economical option for precision frequency reference?
« Reply #33 on: July 21, 2015, 01:24:50 am »
Economical is a very relative term. Something like this is ready to go:
http://www.ebay.com/itm/281701995263
I have no experience with this unit nor the seller but it looks good.

Another option is this:
http://www.ebay.com/itm/FEI-fe-5680b-rubidium-oscillator-With-1pps-20mhz-output-ONLY-10mhz-NEED-to-MOD-/291419889143?pt=LH_DefaultDomain_0&hash=item43d9fa9df7
I purchased one from this seller and have modified it to output 10MHz. It was only a handful of cheap parts to do so. The information is mentioned in his auction. If you need cheaper than $65, then the options get rather few.

I ordered one of the "needs to be modified" FE-5680B units from the eBay link you provided above.

Just received it--it came with a DB15/VGA connector. Did yours have a VGA connector?
 

Offline Lightages

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Re: Economical option for precision frequency reference?
« Reply #34 on: July 21, 2015, 03:01:33 am »
Actually I think it is called an HD15 connector. Yes that is how mine came.
 

Offline edpalmer42

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Re: Economical option for precision frequency reference?
« Reply #35 on: July 21, 2015, 04:31:52 am »
Looks like your the 1st kid on the block with one of these old-timers so PLEASE keep us posted with your finding. 

Was my message on the previous page too long for you?   >:(

Here's the condensed version:

It works.
The longer you let it run, the better it works.

The end.

 

Offline Shock

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Re: Economical option for precision frequency reference?
« Reply #36 on: July 21, 2015, 06:17:09 am »
Pinouts for the Lucent/Symmetricom Z3811A Z3812A (use at your own risk)
http://www.febo.com/pipermail/time-nuts/2014-October/087674.html

Some software made by the late Ulrich Bangert, that you might find useful, made compatible (see readme) for the Lucent/Symmetricom Z3811A Z3812A.
http://www.nc7j.com/downloads/ng7m/Time-Nuts/Z38XX-Modified-for-Lucent-Z3811A-Z3812A/readme.txt
http://www.nc7j.com/downloads/ng7m/Time-Nuts/Z38XX-Modified-for-Lucent-Z3811A-Z3812A/Z38XX.zip

A Frequency Doubler and Distribution Amplifier by Gerhard W. Hoffmann
http://www.hoffmann-hochfrequenz.de/downloads/DoubDist.pdf

HP/Agilent/Keysight product page
http://www.keysight.com/en/pd-Z3810AS%3Aepsg%3Apro-pn-Z3810AS/gps-timing-system?cc=GW&lc=eng
Discontinued product document
http://www.keysight.com/upload/cmc_upload/All/Disco_Products_not_on_site.pdf

HP says this product was sold to Symmetricom, who is now owned by Microsemi.
The Z3811A Z3812A are made to Lucents KS24361 standard to operate with their mobile equipment.

If anyone has success finding more or specific manuals/schematics for the Z3811A Z3812A please let us know.

===============

There is some Lucent RFTG (comparison use only) info on the ko4bb.com website, search for "RFTG".

User guide for the Z3801 (comparison use only).
http://www.leapsecond.com/museum/z3801a/097-z3801-01-iss-1.pdf
« Last Edit: July 25, 2015, 01:59:36 pm by Shock »
Soldering/Rework: Pace ADS200, Pace MBT350
Multimeters: Fluke 87V, 117, 27/FM       >>> WANTED STUFF <<<
Oszilloskopen: Lecroy 9314, Phillips PM3065, Tektronix 2215a, 314
 

Offline edpalmer42

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Re: Economical option for precision frequency reference?
« Reply #37 on: July 21, 2015, 06:31:49 am »
Yes, Ulrich's program, Z38XX, works quite well.  Other than the initial recognition, it doesn't seem to have any problem with the RTFG.

Be careful when you're searching for info on the RFTG.  There were two versions that were rather different from each other.  The one we're talking about includes two OCXOs.  The other version had one OCXO and a Rubidium standard.  Internally, the two versions are quite different.

Ed
 

Offline Shock

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Re: Economical option for precision frequency reference?
« Reply #38 on: July 21, 2015, 06:45:27 am »
Yes, Ulrich's program, Z38XX, works quite well.  Other than the initial recognition, it doesn't seem to have any problem with the RTFG.

Be careful when you're searching for info on the RFTG.  There were two versions that were rather different from each other.  The one we're talking about includes two OCXOs.  The other version had one OCXO and a Rubidium standard.  Internally, the two versions are quite different.

Ed

Yes exactly don't go reading about a 9 pin connector and blow yours up or trash the firmware or config somehow, there is a certain level of competency required and that includes not making assumptions.

Ed do you have the Z3811A Z3812A or any other info on them?
« Last Edit: July 21, 2015, 06:48:36 am by Shock »
Soldering/Rework: Pace ADS200, Pace MBT350
Multimeters: Fluke 87V, 117, 27/FM       >>> WANTED STUFF <<<
Oszilloskopen: Lecroy 9314, Phillips PM3065, Tektronix 2215a, 314
 

Offline edpalmer42

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Re: Economical option for precision frequency reference?
« Reply #39 on: July 21, 2015, 03:31:23 pm »
Ed do you have the Z3811A Z3812A or any other info on them?

Yes, I have the Z3811A / Z3812A pair aka Z3810AS aka KS-24361 aka RFTG-u.  ::)  I bought them a few months ago for a spare.  My tests shown earlier in this thread were done on that pair.

Unfortunately, the only info we have is whatever you can figure out or others have figured out.  The best source is the Time-Nuts mailing list.

FYI, here's some of the info that Z38xx shows when hooked up to the Z3811AS.

Ed
 

Offline SoundTech-LG

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Re: Economical option for precision frequency reference?
« Reply #40 on: July 21, 2015, 03:34:16 pm »
This is a really interesting thread, but finding it pretty difficult to determine what models are being referenced during each post. (hard to follow). Describing a model using "it" without a prior mention of exactly what "it" is,  is really confusing. Thunderbolts, RFTG, RFTG-u, Z3810, Z3811, etc., etc., etc...  giving the model # in each post, helps alot, rather than trying to dig through the whole thread trying to figure that out. I currently have here an RFTG (Rb/GPSDO/OCXO), an RFTG-u system with (2) REF0 units, and (1) REF1 unit, (including the Lucent 15 pin Hi Density Xover cable), an RFG-Rb, several decent 10mHz OCXOs, and (3) Stanford Research FS700s . So many clocks, so little time... :)
 

Offline Shock

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Re: Economical option for precision frequency reference?
« Reply #41 on: July 23, 2015, 05:39:37 am »
Does anyone have contacts at HP/Agilent/Keysight, Symmetricom/Microsemi or Lucent/Alcatel-Lucent (before Nokia buys it out) who could get a guy in tech support or sales to dig up the Z3811A / Z3812A pair (Z3810AS) specific documentation? e.g. operation/programming/service manuals

It's a bit expensive for me to get on the phone and get through to the right support from here but I'm certain someone there in the US can dig up the manuals or get hold of the correct person to speak to. Perhaps an installer or servicer might have documentation as well.
Soldering/Rework: Pace ADS200, Pace MBT350
Multimeters: Fluke 87V, 117, 27/FM       >>> WANTED STUFF <<<
Oszilloskopen: Lecroy 9314, Phillips PM3065, Tektronix 2215a, 314
 

Offline edpalmer42

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Re: Economical option for precision frequency reference?
« Reply #42 on: July 23, 2015, 06:44:25 am »
Does anyone have contacts at HP/Agilent/Keysight, Symmetricom/Microsemi or Lucent/Alcatel-Lucent (before Nokia buys it out) who could get a guy in tech support or sales to dig up the Z3811A / Z3812A pair (Z3810AS) specific documentation? e.g. operation/programming/service manuals

It would be wonderful if someone could find such documentation.  In the meantime, all members of the Z38xx family speak the same language.  I have a Z3801A and the manual is available online for it.  But I found that the command section of the Z3805A manual (also available online) was more useful.  Between these two documents, the Z38XX program from Ulrich Bangert that can talk to almost all the Z38xx units as well as a few others, and the reverse-engineering efforts of the members of the Time-Nuts mailing list, we've got quite a lot of info on a unit that was never intended to be publicly available.

Ed

 

Offline SoundTech-LG

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Re: Economical option for precision frequency reference?
« Reply #43 on: July 24, 2015, 07:02:35 pm »
The HP 70310A Precision Frequency Reference is a Slot module that was available for the 70004A / 70001A MMS systems...
Included a PLL, but only an OCXO (by Corning) driving it. capability to lock an external ref as well. HP sold em' for around $5K, an interesting item 10mHz, 100mHz out with Distr. Amp option.  Power Supply for the modules is a 40kHz bus around 27 VRMS. OCXO uses 20VDC. Look on the bay.
 

Offline motocoder

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Re: Economical option for precision frequency reference?
« Reply #44 on: July 25, 2015, 01:54:51 am »
edpalmer42 -

I finally powered  up the two Lucent units today. I just have the antenna hooked up indoors, but I thought I'd see how things look. I have the interface cable connected between the two units, and 24V applied from a switching adapter that can supply 3.75A.

When it powers on, it cycles through all 4 LEDs, and then goes into a state with the "NO GPS" and  "FAULT" LEDs lit. Is that normal? I am going to leave it on and see if the state changes, but I wanted to make sure there isn't some issue with these units.

Oh! While I typed this, the REF0 unit LEDs have changed. Now they say "NO GPS" and "ON" - no other lights. REF1 lights are the same - "NO GPS" and "FAULT"
 

Offline edpalmer42

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Re: Economical option for precision frequency reference?
« Reply #45 on: July 25, 2015, 02:42:44 am »
Sounds about right.  I forget exactly what happens, but the lights dance around for a while.  At this point, the GPS is pulling one way, the OCXO is pulling another way, and the poor little micro is just totally confused.  Give it an hour or two to gain some semblance of sanity.  Once the GPS figures out where it is and the OCXO properly warms up, things will start to settle down and you'll see the 'On' light on Ref 0 and the 'Stby' light on Ref 1 both on solid.  If you don't have an RS422 adapter, use the hack described in the first message on the Time-Nuts mailing list.  Get the unit hooked up to a PC so you can see what's happening.  I recommend you use the modified Z38xx program.  It includes some data collection functions so you can track the performance of the unit.  Ultimately, the performance will be dependant on just how good your particular OCXO is and how carefully written the software was.

The picture below shows some of the things Z38xx can show.  You open up each of these views under the View tab on the main screen.

The top left graph shows the number of satellites locked and the Holdover Uncertainty Prediction (HUP).  I like the HUP.  The unit is estimating how far off it would be if it lost all satellites for 24 hours.  The value here is okay, but not great.  My Z3801A moves between about 3.5 us and < 0.5 us.  As the OCXO improves, this should drop.  Less than 1 us is really good.

The top right graph shows the error between the 1 PPS and GPS in blue and the EFC voltage to the OCXO in red.  The way the EFC is bouncing around explains the relatively high HUP and the jumpiness of the 1 PPS.  Hopefully, as the OCXO works the kinks out after its long nap, it will settle down and start showing a smooth graph that slopes either up or down and just runs straight.  This could take 30 days or more.  Although I don't see it on the datasheet, many OCXOs specify 30 days of continuous operation before they meet their aging specs.  Some really high precision units specify at least 90 days.  The longer it runs, the better it will perform.  It's best to leave it running permanently.  The unit's ultimate performance will be determined by your particular OCXO and the design parameters of the software.

The bottom left chart shows the signal strength of each satellite.  If your view of the sky isn't great, or your antenna or cabling isn't very good, you'll see it here.

The bottom right screen is the status report from the unit.  You could run Hyperterm or putty and get this with the command :SYST:STAT? .  It might be a good idea to start with a program like that just to ensure that your communications are working properly.

I won't bother posting another graph of the Allan Deviation.  It has improved some, but until the OCXO settles down, the results aren't particularly meaningful.  Even so, the results shown earlier are good.

Ed
 

Offline motocoder

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Re: Economical option for precision frequency reference?
« Reply #46 on: July 25, 2015, 03:27:05 am »
Fault lights are gone, but still no GPS lock. The relatively insensitive receiver in these older units may not be able to pick up the signal indoors. I may have to figure out how to run a cable outside.
 

Offline edpalmer42

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Re: Economical option for precision frequency reference?
« Reply #47 on: July 25, 2015, 03:30:38 am »
Don't worry about the antenna until you get Z38xx running.  Without it, you're flying blind.

Ed
 

Offline N8AUM

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Re: Economical option for precision frequency reference?
« Reply #48 on: July 25, 2015, 03:47:50 am »
I have been trying to get the Z38XX to run but having no luck and looks like my REF1 unit took a dump today, doesnt seem to be receiving anything anymore, yellow GPS light just stays on now. It was working yesterday (excepts the com prog.)
 

Offline motocoder

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Re: Economical option for precision frequency reference?
« Reply #49 on: July 25, 2015, 04:24:52 am »
Don't worry about the antenna until you get Z38xx running.  Without it, you're flying blind.

Ed

Ok, I have a USB RS-422 adapter, but I will probably have to do some surgery to get the cable pinout correct. Have you seen any source that gives the pinout for that?

Thanks for posting the detail above - that is really useful.
 


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