Author Topic: EEVblog #456 - CSIRO Rubidium Frequency Standard  (Read 33787 times)

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Offline bingo600

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Re: EEVblog #456 - CSIRO Rubidium Frequency Standard
« Reply #75 on: June 05, 2013, 12:39:12 pm »
who is at the moment doing adev plotting on a free GPS from someone in this thread.

Blush ...  ;)

 

Offline bingo600

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Re: EEVblog #456 - CSIRO Rubidium Frequency Standard
« Reply #76 on: June 05, 2013, 01:24:57 pm »

I'm thinking on getting a FE5680A to test them against each other, do you think this is a good idea, or the FE5680A could be even worse? Of course if I find that both of them are very close to each other I could be certain that both are on spec, but if difference is significant who could I blame for the difference, the HP "High" OCXO oven or the FE5680A?

Any ideas are welcome, I just want to be confident about my measuring device.

Thanks.

Go for a GPSDO

His shipping to EU is usually to high for me
http://www.ebay.com/itm/CIC-GGER-Equivalent-to-Z3815A-GPS-FREQUENCY-TIME-RECEIVER-10-MHz-/271213238400

Untested  :-\
http://www.ebay.com/itm/HP-SYMMETRICOM-Z3805A-GPS-Disciplined-Oscillator-GPS-Frequency-Time-Receiver-/181113452077

Tested
http://www.ebay.com/itm/HP-SYMMETRICOM-Z3805A-GPS-Disciplined-Oscillator-GPS-Frequency-Time-Receiver-/290832846664

Pricey but cool for a lab many 10mhz out - (seems to be of in the internal date) , but it won't affect the 10Mhz
http://www.ebay.com/itm/Datum-9390-52054-GPS-Disciplined-10MHz-Atomic-Clock-Time-Receiver-IRIG-B-1PPS-/281073499525


Both i and another person from this thread  ;)   has a Trimble Thunderbolt GPSDO (the old metal one)

http://www.ebay.com/itm/Thunderbolt-PRECISION-GPS-10Mhz-1PPS-Standard-Easy-Kit-/180419218430
http://www.ebay.com/itm/Thunderbolt-PRECISION-GPS-10Mhz-1PPS-Standard-Easy-Kit-/280649244485

http://www.ebay.com/itm/ThunderBolt-GPS-Disciplined-Clock-10-MHz-and-1-pps-/271207827869


But we got them before the prices skyrocketed (Back then it was $110 for a unit , and $200 for a kit)


Remember an antenna (5volt)

I prefer timing antennas , but have also used normal marine antennas
http://www.ebay.com/itm/GPS-Timing-Reference-Antenna-26db-Gain-N-connect-/270881742870
http://www.ebay.com/itm/PCTEL-MAXRAD-GPS-26dB-TIMING-REFERENCE-ANTENNA-KIT-GPS-TMG-26NMS-NEW-/121121457131

http://www.ebay.com/itm/Nokia-470290a-101-Timing-Reference-Antenna-20-db-N-type-GPS-Waterproof-antenna-/290853216689


I think this is the one Trimble uses for the Thunderbolt.
http://www.ebay.com/itm/trimble-gps-antenna-p-n-28367-70-/290508227053



The HP/Symetricomm GPSDO's are good but prob need 24 or 48volt , so keep an eye on the power requirements.
And N-Connectors for the Antennas ....


Well this should give you a hint ....



/Bingo
 

Offline carloscuev

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Re: EEVblog #456 - CSIRO Rubidium Frequency Standard
« Reply #77 on: June 05, 2013, 01:59:37 pm »
But we got them before the prices skyrocketed (Back then it was $110 for a unit , and $200 for a kit)

WOW $110 for a GPSDO, that would have been great. Sadly I panicked about a FE5680A at $89 (free shipping) on ebay and already bought one, the next cheap one is about $120 (incl. shipping). At least the seller claims it's  one of the latest UN-7XXXXX models available from eBay with 2004 manufacturing date. Having bought the counter and the rubidium standard, I have left about 30-40 bucks.

How difficult could it be to later make a GPSDO using this FE5680A and a GPS receiver with 1 PPM output? Any place to start reading the basics about how to do it?

Is there any GPS receiver unit recommended for this? Maybe I can afford a cheap one.

Anyway, I hope the OCXO in the HP counter is working good, seller claimed last calibration was in 2010, but cannot trust him because he doesn't seem knowledgeable about test equipment, he mainly sells used low end audio stuff.
 

Online EV

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Re: EEVblog #456 - CSIRO Rubidium Frequency Standard
« Reply #78 on: June 05, 2013, 03:42:32 pm »
WOW $110 for a GPSDO, that would have been great. Sadly I panicked about a FE5680A at $89 (free shipping) on ebay and already bought one, the next cheap one is about $120 (incl. shipping). At least the seller claims it's  one of the latest UN-7XXXXX models available from eBay with 2004 manufacturing date. Having bought the counter and the rubidium standard, I have left about 30-40 bucks.

How difficult could it be to later make a GPSDO using this FE5680A and a GPS receiver with 1 PPM output? Any place to start reading the basics about how to do it?

Is there any GPS receiver unit recommended for this? Maybe I can afford a cheap one.

Anyway, I hope the OCXO in the HP counter is working good, seller claimed last calibration was in 2010, but cannot trust him because he doesn't seem knowledgeable about test equipment, he mainly sells used low end audio stuff.

FE5680A is good but it is not easy to trim to correct frequency.

http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:fe5680a_faq

Now you need also GPSDO and your counter to check this FE5680A.

You can do GPSDO yourself or buy a kit:

http://www.jrmiller.demon.co.uk/projects/ministd/frqstd0.htm
 

Offline carloscuev

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Re: EEVblog #456 - CSIRO Rubidium Frequency Standard
« Reply #79 on: June 05, 2013, 04:21:27 pm »
Now you need also GPSDO and your counter to check this FE5680A.
I was afraid of that.

You can do GPSDO yourself or buy a kit:
I think I'm going to go with this alternative :)
There are several 10Mhz OCXOs in eBay:
http://www.ebay.com/sch/i.html?_odkw=OCXO&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR11.TRC1&_nkw=OCXO+10Mhz&_sacat=0
Which one should I go for? Could I assume anyone would work because it will be disciplined by th GPS?
About the GPS, I've seen lots of odules on eBay with SiRF 2, 3 and 4, any recommendation? is the bigger SiRF chipset version, the better?

There's an interesting Fastrax UC430 that includes a chip antenna, has 1 PPS output
http://www.ebay.com/itm/190849374321

Also a chinese SIMCOM module, not sure if it has 1 PPS output
http://www.ebay.com/itm/180795135748

There are also some Globalsat models, they have 1 PPS output
http://www.ebay.com/itm/140976661175

Sorry for all this questioning, I'm a long time hobbyist, but just starting to learn all this precise timing arts.
 

Online EV

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Re: EEVblog #456 - CSIRO Rubidium Frequency Standard
« Reply #80 on: June 05, 2013, 04:49:49 pm »
I have some of these:
http://www.ebay.co.uk/itm/Navman-jupiter-T-Tu60-GPS-Kit-1pps-10khz-GPS-Module-/260790984470?pt=US_Ham_Radio_Amplifiers&hash=item3cb85a9f16

and these:
http://www.ebay.com/itm/10MHZ-ISOTEMP-Reserch-OCXO-134-10-CRYSTAL-OSCILLATOR-/170489162873?pt=LH_DefaultDomain_0&hash=item27b1f22c79

and I have bought some PCB's from Miller to make control board for them. I have however not assembled them yet, maybe next winter time I do it. I have a trimble thunderbolt GPS disciplined standard already, so there is no hurry.
 

Online EV

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Offline bingo600

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Re: EEVblog #456 - CSIRO Rubidium Frequency Standard
« Reply #82 on: June 05, 2013, 07:02:12 pm »
@Carlos

You'd need the GPS receivers that EV points at if you build the Miller GPSDO
The design relies on the 10Khz output from the Jupiter's , 1PPS is not going to do it.

For a really nice 1PPS receiver , get this one (supposed to be among the best)
http://www.ebay.com/itm/Motorola-ONCORE-M12-T-timing-gps-receiver-1pps-100hz-/290656401551


/Bingo

Ohh i just found this one - more reasonable price
http://www.ebay.com/itm/TRIMBLE-GPS-RECEIVER-10MHZ-CLOCK-THUNDERBOLT-/171048961859

The TBolt needs 5v and +/- 12v , you can use a Cisco 1700 powersupply .. like here
http://www.ebay.com/itm/Thunderbolt-10mhz-GPS-Power-Supply-30W-12V-12V-5V-/280703342103

Or any reasonable clean switchmode  , even though linear would be best.

I use a Cisco PSU ....
 

And you could start out with a cheap 5v gps antenna
http://www.ebay.de/itm/OPEK-3V-5V-GPS-1102-Active-Antenna-for-Garmin-G5010U-5M-/140892128742


« Last Edit: June 05, 2013, 07:13:23 pm by bingo600 »
 

Online EV

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Re: EEVblog #456 - CSIRO Rubidium Frequency Standard
« Reply #83 on: June 05, 2013, 07:53:11 pm »
And you could start out with a cheap 5v gps antenna
http://www.ebay.de/itm/OPEK-3V-5V-GPS-1102-Active-Antenna-for-Garmin-G5010U-5M-/140892128742

I have two antennas like this in use and they work very well. I have installed the reciever and the power suply to the same case. They can be seen in the next link.
http://www.ebay.co.uk/itm/Easy-Kit-Thunderbolt-PRECISION-GPS-10Mhz-1PPS-Standard-/280649530260?pt=LH_DefaultDomain_0&hash=item415803fb94

Picture about the finished device is attached.
 

Offline zibadun

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EEVblog #456 - CSIRO Rubidium Frequency Standard
« Reply #84 on: June 05, 2013, 08:49:26 pm »
I've got one of those HP Z3805A units. It works flawlessly and has many outputs, including Rs232.  They used to cost a lot more (around $400) a few years ago before a truckload of thunderbolts appeared.  I think it's a bargain at the current price.

3805 usually sold without an antenna  but it Works with most "active" gps pucks. It may show an alarm light because the new antennas draw very little current and the device thinks it's unplugged.  The trick is to add a resistor between the center conductor and ground of the coax connector.  Don't believe this affects the accuracy.   Don't forget the setting for coax propagation delay which based on the cable length and velocity factor. a guesstimate is probably ok here :)
 


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