[time-nuts] Z3801 replacement

paul swed paulswedb at gmail.com
Fri Jun 28 19:39:26 UTC 2013


Tbolts been good for my uses. Nice and simple no muss or fuss.
I think I paid $139.
Regards
Paul.


On Fri, Jun 28, 2013 at 11:45 AM, Bob Camp <lists at rtty.us> wrote:

> Hi
>
> Ok, so the 100 MHz cleanup oscillator hopefully will be about -130 dbc /
> Hz or better at 100 Hz offset. That would mean a -150 dbc / Hz OCXO is
> roughly a tradeoff at 100 Hz. At 1KHz your cleanup oscillator should be
> around -150 to -160. That would put the 10 MHz at -170 to -180 to be in the
> same ballpark. You will have trouble getting a divider and phase detector
> to hit -180, so the simple answer is to keep things cheap and roll off
> inside about 100 Hz or so. Spurs are an unknown, but they likely will mean
> you want to roll off sooner rather than later as well.
>
> I'd go shopping for something that's got better than -155 dbc / Hz at 100
> Hz and see what you can find. The TBolt OCXO meets that, there are other
> OCXO's that also do so. The auction sites often have TBolt pulls for < $40.
> I'd stick with a modern hermetic part if possible. It'll make for fewer
> issues down the road.
>
> Bob
>
> On Jun 28, 2013, at 10:22 AM, Jim Sanford <wb4gcs at wb4gcs.org> wrote:
>
> > Bob:
> > Thanks.
> > You correctly anticipated that I will use this to lock a 100 MHz
> Oscillator, and either multiply or lock from there.  (I'm considering a
> VCXO at 1GHz as well, it would either be locked to 100 MHz or 10 Mhz.
>  Haven't decided yet, also considering multiplying up to 1000 and then from
> there to 2Ghz, 3Ghz, and 5.  Haven't decided about 10 Ghz yet.
> >
> > Appreciate the info.  The units on ebay are cheaper than the VCXO I was
> considering (first time I looked, they were more), so will probably just do
> that.
> >
> > Thanks again,
> > Jim
> > wb4gcs at amsat.org
> >
> > On 6/28/2013 10:07 AM, Bob Camp wrote:
> >> Hi
> >>
> >>
> >> On Jun 28, 2013, at 9:45 AM, Jim Sanford <wb4gcs at wb4gcs.org> wrote:
> >>
> >>> All:
> >>>
> >>> My Z3801 no longer works, and I've not been able to get any new ideas
> on it, so am looking for a replacement.
> >>>
> >>> I've come across a nice 10 MHz that has very good phase noise (-145db
> or so at 10 KHz offset), but costs $175 in single quantities (digi-key, I
> think.)
> >> The OCXO in the TBolt is about -165 at 10 KHz
> >>
> >>>  I was considering using one of W1GHz's boards to lock it to a jupter
> GPS engine that I already have.  Several people have told me this is
> overkill, recommending the Thunderbolt.
> >>>
> >>> I've read that there are various OXCXs used in Thunderbolts, some OK,
> some not so good.
> >>>
> >>> Looking on ebay right now, I see a Nortel Trimble NTBW50AA, a
> Symmetricom, NTBW50AA, and another Nortel.
> >>>
> >>> Does anybody have experience with these?
> >> Yes
> >>
> >>>   I'm particularly interested in the best phase noise I can get.
> >> Spurs are what will kill you.
> >>
> >> Phase noise is about 10 db worse than the TBolt far removed. It's
> similar close in.
> >>
> >>>  This will be station master frequency reference, and will ultimately
> lock stations up to 10 GHz.
> >> Simple answer is to run a clean up oscillator at 100 MHz and then go
> from there. None of the GPSDO's have low enough spurs to really do an
> excellent jobs at 10 GHz.
> >>
> >>
> >> Bob
> >>> Thanks & 73,
> >>> Jim
> >>> wb4gcs at amsat.org
> >>>
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