[time-nuts] Re. DIY atomic "resonator"-- replacing SDRs

Alex Pummer 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

73

KJ6UHN

Alex


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
>> time-nuts.
>
> 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.
>
> Indeed-
>
> > 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.
>
> Cheers,
> Magnus
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 2016.0.8012 / Virus Database: 4769/14290 - Release Date: 
> 04/11/17



More information about the time-nuts mailing list