Brooke,
One use for the R variants of the Fluke/Pendulum counters is/was for
calibrating base-stations. They had issues with ovens and turning the
counter to the side as you lifted it up. A rubidium inside solved that
in a nice way.
It's not all government work you know. :)
Cheers,
Magnus
On 10/26/2014 10:45 PM, Brooke Clarke wrote:
Hi Karen:
The ones you mention are all stand alone Rb oscillators that need to be
calibrated to set their frequency.
This was the historical way that crystal oscillators were calibrated
every year or so. The great advantage of Rb over crystal oscillators is
that their drift is specified in months instead of days.
A much better - more modern idea - is the GPS Disciplined Oscillator
(GPSDO). It keeps the oscillator "calibrated" in real time.
A popular crystal based GPSDO is the Trimble ThunderBolt:
http://www.prc68.com/I/ThunderBolt.shtml
Another crystal based GPSDO is the HP Z3805:
http://www.prc68.com/I/Z3805A.html
There are many more commercial GPSDOs and this list has discussions that
show they can be a do it yourself project for under maybe $10, but
require a number of sophisticated skills.
I have the just released LTE-Lite GPSDO Evaluation Kit with 10MHz TCXO
on order. Seems to offer good performance for the dollar.
http://www.ebay.com/itm/171504585820
The only advantage of a Rb GPSDO over a crystal GPSDO is for the case
where the GPS updating has not happened for some time.
This might be due to a power failure lasting some days or that the
oscillator will be used where there's no GPS access and it only gets
"calibrated" then used much later.
The Stanford Research PRS-10 Rb oscillator can be used stand alone where
it time stamps an external 1 Pulse Per Second input, or as part of a
GPSDO where an external GPS receiver supplies it with a 1 PPS input.
http://www.prc68.com/I/PRS10.shtml
The Thunderbolt can be custom modified to drive an external Rb
oscillator, like the ones you mentioned, but that requires some
technical sophistication.
Note the ThunderBolt and Z3805 are complete GPSDOs in a box, just
connect power and a GPS antenna.
The PRS-10 requires an external GPS receiver and antenna. A a practical
matter that means it's more work to maintain the PRS-10 because there's
more opportunity for problems like disconnecting a cable.
PS Stanford Research offered a version of their SR620 Time Interval
counter that included a Rb oscillator (not a GPSDO) that some government
agencies purchased, but for normal use you really don't need a Rb
oscillator, so the CNT-91R appears to be a similar way so sell it to a
government with a lot of money to spare. So don't feel pressured to use
an Rb oscillator. http://www.prc68.com/I/TandFTE.shtml#SR620
Mail_Attachment --
Have Fun,
Brooke Clarke, N6GCE
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
http://www.prc68.com/I/DietNutrition.html
Karen Tadevosyan wrote:
Hello All,
Can I have your recommendation regarding a choice of 10 MHz rubidium
source
(available now on eBay like FE-5680; LPRO-101; LPFRS; FRS etc.) as a
reference signal for my frequency counter Pendulum CNT-91.
Thanks in advance.
Karen, ra3apw
---
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от вирусов avast!
http://www.avast.com
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