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

[Bob kb8tq]

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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