[time-nuts] LPFRS phase ripple?
kb8tq at n1k.org
Thu May 25 08:59:56 EDT 2017
Even more to the point, why did they put in 5,000 hour caps and run them right at
maximum temperature? No derating the voltage or anything …. It looks very much
like a design decision made by the purchasing department :)
> On May 25, 2017, at 8:12 AM, Matthias Jelen <Matthias.Jelen at gmx.de>wrote:
> Hi Tim,
> yes, both units on my workbench, same setup, same power supply.
> I´ll exchange the caps.
> I wonder why they made efforts to design a physics package with 20 years lifetime, just to put wet electrolytic caps into such a hot environment.
> Am 25.05.2017 um 13:27 schrieb Tim Shoppa:
>> Matthias, are the units all over in the same thermal environment when you test them?
>> A period of 150s or so in a wobble sounds like a not perfectly damped thermal cycle time of a lightweight oven or lamp.
>> Reminds me a little of the unit to unit variation in HP Wien Bridge oscillator amplitude stability (also a lamp!)
>> Tim N3QE
>>> On May 23, 2017, at 3:40 AM, Matthias Jelen <Matthias.Jelen at gmx.de> wrote:
>>> Hello Time-Nuts,
>>> i´ve been playing with some Rbs recently.
>>> I compared two LPFRS-01 to a PRS-10. One seems to behave quite well (compared to the specs given here: http://www.spectratime.com/uploads/documents/isource/iSource_LPFRS%20Spec.pdf) - short term stability specs are met), the other one shows quite some phase ripple (appx. 1 ns RMS with a frequency around 0.007 Hz) which spoils ADEV in the 60 - 200s range, very similiar to the typical GPSDO bump. Long term stabilty is OK.
>>> Unfortunatly I didn´t find any schematics on the web. Has anyone encountered a similiar problem with this unit? Any idea were this might come from? My first guess would be a problem in the control loop locking the VCXO to the Rb, but I have no clue which time constants are used in the PLL.
>>> Any hints are appreciated.
>>> time-nuts mailing list -- time-nuts at febo.com
>>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
More information about the time-nuts