[time-nuts] Re: Query about List and about 10 MHz Distro

[Dana Whitlow]

Bob, my own motivation  for going to fiber was entirely different.  I
simply wanted to
run 10 MHz all over the place from reference sources in disparate
locations in the
house, and I quickly discovered that cable leakage was embarrassingly
severe.  So
I shut down and began contemplating a fiber link.  But then reality set in
and I realized
that running fiber across the house had its own big problems, so I set the
project aside.

Dana


On Sat, Aug 28, 2021 at 3:32 PM Bob kb8tq <kb8tq at n1k.org> wrote:

> Hi
>
> With a whole variety of pretty good OCXO’s going for cheap money
> on eBay, it’s likely less expensive to do cleanup oscillators on the link
> compared to going crazy with low noise optical this or that. Yes, you
> will be getting something in the high 150’s for noise, but still pretty
> good
> for $10.
>
> If you need better, spend $50 or so on a 10811. Still less money than
> some of the crazy fiber stuff.
>
> With either one, send over a high enough frequency that the loop isn’t
> dealing with reference spurs in any significant way. Given the clock rates
> Ethernet runs at these days, that part should be fairly straightforward.
>
> This *assumes* that there is a crossover somewhere practical between
> the fiber noise and the noise on the optical gear. You should be able to
> work out what it is with some fairly normal phase noise or ADEV testing.
>
> Bob
>
> > On Aug 28, 2021, at 3:03 PM, Dana Whitlow <k8yumdoober at gmail.com> wrote:
> >
> > I was looking for something similar about 18 months or so ago.  Although
> I
> > haven't taken any
> > action yet, I concluded that one could do a nice job for under $200 per
> > segment, including the
> > transmitter and receiver modules and lots of connectorized multimode
> > fiber.  What I *don't* know
> > is what the phase noise performance would be, except that I do know that
> > the fiber's VF *is*
> > materially influenced by temperature.
> >
> > I was looking primarily at the HFBR-2416 for the fiber receiver, and the
> > HFBR-1412 (standard
> > power) or the HFBR-1414 (high power option) for the transmitter   Unlike
> > most of the available
> > models, these are fundamentally analog devices, meaning that you can
> > transmit sinewave
> > 10 MHz through them.  At the time I was looking, Mouser was selling these
> > for about $20 each.
> >
> > See the datasheet at
> >
> https://www.mouser.com/datasheet/2/678/AV02-0176EN_2019-02-15-1827546.pdf
> > with particular attention to page 21 regarding the HFBR-2416 receiver.
> >
> > I was also looking at Fiber Instrument Sales for patch cords.  We bought
> a
> > lot of fiber stuff from
> > them at Arecibo, and I was always happy with them.  See:
> >
> https://www.fiberinstrumentsales.com/catalog-cable-assemblies?gclid=Cj0KCQjwvaeJBhCvARIsABgTDM7eNTkP2nQbyFzhcwDE38VnSEP879MBKV1ZyDq2YrnEtOn7_VfzjbkaAtpfEALw_wcB
> >
> > Somebody had pointed out yet another source of connectorized fibers
> ("patch
> > cords") to me, but I cannot find the name
> > at the moment.
> >
> > Dana   K8YUM
> >
> >
> > On Sat, Aug 28, 2021 at 11:52 AM AC0XU (Jim) <James.Schatzman at ac0xu.com>
> > wrote:
> >
> >> I am hoping that you can help me about a couple of things:
> >>
> >> 1) My time-nuts summaries sometimes appear unformatted and unreadable.
> All
> >> the text from all the postings is crammed together without spacing. How
> can
> >> I fix it?
> >>
> >> 2) I want to distribute 10 MHz references by fiber. There are
> >> RF-over-Fiber products available, but too expensive for me (thousands of
> >> $$$ per xmit/rcv set).  I am thinking that it should be possible to use
> >> fiber Ethernet components to do this. I don't mean IEEE 1588 but a much
> >> simpler, no-computer-required, solution. Possibly just converting sine
> wave
> >> (coax) to square wave (fiber) to sine wave (coax). I am looking for a
> low
> >> cost solution. Any thoughts or recommendations??
> >>
> >> Thanks!
> >>
> >> Jim
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