[time-nuts] LPFRS phase ripple?
matthias.jelen at gmx.de
Thu May 25 08:12:59 EDT 2017
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.
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