[time-nuts] The 5MHz Sweet Spot

Said Jackson saidjack at aol.com
Mon Nov 4 02:52:16 UTC 2013


Bert,

Let me know if you can do stable >1s loops in the analog domain with reasonable cap sizes say <220uF. I would be impressed. I tried.

Bye,
Said

Sent From iPhone

On Nov 3, 2013, at 14:51, EWKehren at aol.com wrote:

> We are looking at room temperature 5 and 10 MHz XO's for cleaning up Rb and 
> DDS. Filter time 1 to 20 seconds and thermal mass to keep temperature 
> influence  low. Hard to find XO's, so what we are testing is older TCXO's where 
> we remove  the TC and use the tuning circuit for loop control. Any 
> suggestions? Maybe  slightly off subject but the experts are here.
> Thanks  Bert Kehren
> 
> 
> In a message dated 11/3/2013 4:41:43 P.M. Eastern Standard Time,  
> saidjack at aol.com writes:
> 
> The  partial answer is: yes as they typically use 10MHz crystals too. But 
> the loop  BW is so wide (10Hz or more) that the crystal jumps get compensated 
> very  quickly.
> 
> We have not seen any real frequency jumps in 100's of CSACs we  tested that 
> use vapor cells just like RB's do, so from my experience I have  never seen 
> a discrete frequency jump in an Atomic oscillator..
> 
> Notice  that CSACs do jump significantly in frequency right after power on 
> when they  achieve atomic lock, typically about 60s after power on.
> 
> Vapor cell  atomic clocks typically have other issues such as excessive 
> retrace, loss of  vacuum and a subsequent slow drift in frequency, and almost 
> instantaneous loss  of atomic lock causing frequency jumps when operated 
> above max  temperature..
> 
> Sent From iPhone
> 
> On Nov 3, 2013, at 13:28, Hal  Murray <hmurray at megapathdsl.net> wrote:
> 
>> 
>> Do low cost  recycled Rubidiums have any quirks equivalent to frequency 
> jumps 
>> in  crystals?
>> 
>> 
>> 
>> -- 
>> These are my  opinions.  I hate spam.
>> 
>> 
>> 
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