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

[Bob kb8tq]

Hi

Skin depth is what gets you with most coax at 10 MHz, even with the “double 
shield” stuff. Hardline with a nice heavy outer would do better. It’s not terribly 
practical around the typical lab. Might not be a bad choice for a “burry in the yard”
setup though. With normal cable, the losses from the soil at normal burial 
depths make a good shield, that makes dealing with it questionable even there ….

Bob

> On Aug 29, 2021, at 9:36 AM, Robert DiRosario <ka3zyx at comcast.net> wrote:
> 
> What about double shielded RG-223, or Thinnet ethernet cable?
> Most Thinnet has both a braided shield and a foil wrap.
> 
> Robert
> 
> On 08/28/2021 08:26 PM, Bob kb8tq wrote:
>> Hi
>> 
>> Anything you do that has a bunch of 10 MHz cables running out from here or there
>> will impact your ability to listen to WWV at 10 MHz :)  Other than killing all the sources,
>> there is no silver bullet.
>> 
>> Bob
>> 
>>> On Aug 28, 2021, at 7:57 PM, Dana Whitlow <k8yumdoober at gmail.com> wrote:
>>> 
>>> 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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