[time-nuts] OCXO PLL gains?

[Bob kb8tq]

Hi

The bumps you are seeing are likely due to some sort of filtering in the EFC input
to the oscillator you are trying to lock up. 100 Hz is not all that uncommon for a filter
cap rolling off noise on the EFC line. Indeed it can be from other things, it’s just a guess….

Bob

> On Feb 4, 2019, at 10:44 AM, Anders Wallin <anders.e.e.wallin at gmail.com> wrote:
> 
> I played around with this today, recording 5 minute runs: freerunning, P/10
> gain, P gain, 10x P gain (where P is some unknown value...)
> I then added either a 1M/100n or 500k/100n integrator which really only
> shows in the TDEV-plot, not in the PN-plot.
> https://photos.app.goo.gl/V9xL5MkVsL6RLRXJ7
> 
> maybe "P/10, with integrator" is the best one so far? Seems any increase in
> P-gain always creates an ugly PN-bump?
> Increasing the I-gain is maybe the next thing to try, either with a shorter
> RC-constant, or by increasing the I-weight in the summing op-amp..
> Didn't have time to read the references much - so this is mostly trial and
> error for now...
> 
> Anders
> 
> On Sun, Feb 3, 2019 at 7:01 PM Tom Van Baak <tvb at leapsecond.com> wrote:
> 
>> Bert,
>> 
>> That looks like a very nice board. Thanks for posting. Let us know how to
>> obtain one; as board, kit or product.
>> 
>> /tvb
>> 
>> N.B. The original posting was aol / html. It has been reformatted below to
>> work with the time-nuts server.
>> 
>> 
>> ----- Original Message -----
>> From: ew
>> To: time-nuts at lists.febo.com
>> Cc: j.koegel at bluewin.ch
>> Sent: Sunday, February 03, 2019 5:26 AM
>> Subject: Re: [time-nuts] OCXO PLL gains?
>> 
>> There is a need for clean up loops across time-nuts applications. Right
>> now Corby has one to test  clean up for a HP 5065A and a HP 5061B. How ever
>> there is room for improvement.
>> 
>> In my simple mind there may be an answer for most applications and enough
>> brains among time nuts to define and develop a loop. Many of the telecom
>> GPSDO's use frequency to correct for time, FE5680 a candidate even other
>> Rb's depending what you have and try to accomplish. Morion MV89A, HP10811,
>> Austron 1150, FRK, M100, FTS1200, M1000, OSA8600 all candidates for the
>> other side.
>> 
>> I recently did two OCXO boards one based on many time nuts inputs. Did not
>> find some one to pick up the designs and make it available. I than decided
>> to post Gerber files and based on off list questions and comments boards
>> have been made.
>> 
>> I propose something similar. Our experts come up with an answer, I do a
>> board and add it to my next order, projects are waiting to be ordered after
>> the Chinese holiday. As always Corby will along with Juerg get the first
>> boards and once passed Corby's test I will release information. I do make
>> layout mistakes and I do not want mistakes out there. Cause confusion with
>> corrected boards.
>> 
>> I keep looking at Microsemi 4145C datasheet and I am convinced with the
>> time nuts brains out there one could get close. There is a digital loop
>> between an the HP5071A and a OSA8600 and an analog loop between 8600 and a
>> Wenzel Super Low Noise OCXO. Not now, walk before we run, but the brains
>> and parts are out there.
>> 
>> Bert Kehren
>> 
>> Attached a picture of our first board, we now have later versions, one
>> based on Wenzel 600 sec. design and one similar to the dither filter used
>> in the HP GPSDO. We are not experts.
>> 
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