[time-nuts] Re. DIY atomic "resonator"-- replacing SDRs
alex at pcscons.com
Tue Apr 11 14:25:16 EDT 2017
YES SDRs [step Recovery Diodes] is hard to find today, but there many--
PIN -- diodes, which exhibits that effect, even some standard rectifier
diodes could be used for, despite of that Magnus is right, today are
better solutions available e.g. PLLs with 10GHz prescalers
On 4/11/2017 9:22 AM, Magnus Danielson wrote:
> On 04/11/2017 05:54 PM, Richard (Rick) Karlquist wrote:
>> On 4/11/2017 12:31 AM, Andre wrote:
>>> Has anyone else either built an atomic clock around a bare Rb lamp
>>> module "core" or attempted
>> Not a DIY project, but I was the RF designer on the HP 10816 rubidium
>> standard, which never made it to product introduction (a half dozen
>> working pilot run units were built in 1982). I would say this task is
>> probably beyond the scope of a DIY project, at least for most
> Probably right.
>> The Rb lamp drive circuit (particularly getting the
>> lamp to light up) is very challenging.
> There would be none. It would be replaced by a laser. That has its own
> set of "problems" but different.
>> The step recovery diode multiplier is very challenging.
> Today you would not go the SRD route in synthesis.
> Besides, SRDs can be hard to find these days.
>> The photodetector and loop integrator is non trivial.
> I'd expect the loop integrator to be done in digital, which eases up
> on some of the design problems.
>> The synthesizer is the one thing that is easy in 2017.
> > The oven is also no simple thing to get
>> low tempco. Unlike a crystal, you have a lot of heat being
>> generated by the lamp, etc. The lamp needs to be at a different
>> temperature than the other cells.
> Going down the laser-route, the balance of temperature between the
> cells is no longer a relevant problem. Further, the lamp and its heat
> is gone.
>> You have to keep the tip
>> off at the lowest temperature to keep the Rb in place and not
>> "flood" the cell and block the light. Etc., etc.
> You still have this problem, but not as a lamp problem but only for
> the resonance cell part.
>> This is in the category of projects where if you were qualified
>> to do it, your time is far too valuable to do it for the amount
>> of money you would save.
> This is the type of project you do not to save any money, but to spend
> and learn.
> Even if done in a much more modern fashion, avoiding several of the
> traditional problems, there is plenty of issues to solve and handle.
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