[time-nuts] Re: Stability question

[jack.davis]

I really don't care about the 1024 week roll over. My only concern is the 10 MHz stability.   I have my frequency counter, spectrum analyzer, my 8VSB analyzer and my network analyzer locked to 10 MHz.  I am using Belden 9913 cable for my antenna feed and I am reluctant to go to LMR type cable  Sent from my Verizon, Samsung Galaxy smartphone by Morse code.700.00 
-------- Original message --------From: va2hdd at ebox.net Date: 3/2/22  9:30 PM  (GMT-08:00)77To: Discussion of precise time and frequencyuhuu8u7 measurement <time-nuts at lists.febo.com> Subject: [time-nuts] Re: Stability question Hi Jack.At work I had to bring GPS signal to one of our labs, which is in the middle of a building with no rooftop access or nearby window. The only I was able to do it was to bring a long run of LMR400 cable from my rooftop antenna on top of the building which connects to a GNSS splitter amplifier in the middle of the path; and then another long LMR400 cable connected to a second splitter and from that second splitter I distribute the GPS signal to the clocks that sync our lab equipment. The total cable run from the antenna to the first splitter is 60 meters (196 feet). The cable from that first splitter to the second splitter is 70 meters (229 feet), and at the output of the second splitter I have cables from 5 meters to 25 meters to bring the signal to each clock. Even with this far from optimal setup I have not experienced insufficient signal level or signal loss problem.That being said, I had problems with two older Datum ExacTime 6000 and 6010 clocks that would take forever to lock or receive only 2 or 3 satellites. They also were affected by a GPS epoch problem.  So I attempted to cure their problems with a GPS receiver upgrade made by a French company called HEOL designs : https://www.heoldesign.com/, the exact product is : https://www.heoldesign.com/N024-GPS-receiver-board-for-Tymserve-2100?lang=en . With the receiver upgrade the long lock delay and intermittent signal loss problems disappeared, and the epoch rollover bug was cured, BUT although the clocked was locked and correcting the "LOCK" LED was never on. It seems that the upgrade board is fully compatible with the TimeServe 2100 but only partially compatible with the ET6000.So I junked the two ET6000 and replaced them with more recent vintage clocks and all is OK since I installed the replacement clocks.  For some strange reason clocks of similar vintage as the ET6000 always synced OK and they still sync perfectly, like an ancient TrueTime NTS-100i.Of course this is my experience and things might be different for you.ClaudeLe 02/03/2022 18:49, Jack Davis a écrit :> CAUTION: This email originated from outside your organization.> Exercise caution when opening attachments or on clicking links from> unknown senders.> > > > > I have a Datum Exactime ET-6000TCXO that I use to lock all my test> equipment to 10 MHz.  My GPS antenna is approximately 200 feet from> the receiver and I have intermittent GPS signal levels and associated> unlocking of my ET-6000TCXO.  I have tried using bigger less loss coax> cable but its just not enough to make it reliable.> > > > I see there is a Symmetricom Kit 142.6150 consisting of a model> 140-615 GPS antenna / downconverter and a model 150-615 upconverter> available to allow longer runs of coax cable.  From what I can tell> there is a local oscillator in the antenna that down converts the> 1,575.42 MHz GPS signal to 4.092 MHz for lower cable loss.  The up> converter on the receiver side apparently another local oscillator> that up converts the 4.092 MHz IF to 1,575.42 MHz.> > > > My question is: will the two local oscillators and the up and down> conversion cause phase noise or frequency instability of the GPS> signals into my ET-6000TCXO?  It does have some sort of flywheel> correction internally but is it enough to keep the 10 MHz timebase> stable?> > > > Thanks,> > Jack  K6YC> > _______________________________________________> > time-nuts mailing list -- time-nuts at lists.febo.com -- To unsubscribe> send an email to time-nuts-leave at lists.febo.com> > To unsubscribe, go to and follow the instructions there._______________________________________________time-nuts mailing list -- time-nuts at lists.febo.com -- To unsubscribe send an email to time-nuts-leave at lists.febo.comTo unsubscribe, go to and follow the instructions there.