[time-nuts] FE-5680A Mechanical Question

EWKehren at aol.com EWKehren at aol.com
Fri Jan 13 12:59:12 EST 2012


we would be talking +- one step and using different rate but reading the  
frequency over 1000 seconds would be my answer. Start at 1 1 Hz rate and 
observe  the lock indicator. At the same time measure frequency.
Bert Kehren
 
 
In a message dated 1/13/2012 12:52:16 P.M. Eastern Standard Time,  
lists at rtty.us writes:

Hi

Another thing that would need to be investigated - How  fast (and how
uniformly) does it respond to a frequency set command. If you  dither, you
care about how long it's at this or that frequency. Measuring  7x10^-13
frequency shifts on the unit probably isn't the best way to check  that out
....

Bob

-----Original Message-----
From:  time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of  EWKehren at aol.com
Sent: Friday, January 13, 2012 6:20 AM
To:  time-nuts at febo.com
Subject: Re: [time-nuts] FE-5680A Mechanical  Question

What we know is that you can set the Rb in 7 E-13. Dithering  would allow  
even closer setting, the question is what rate will the  Rb accept with out 
 
loosing lock or deterioration of the performance.  Some one should explore 
that.  I am still waiting to se some aging.  Taking the 10 MHz output and
than 
use an  analog loop and  something like a Morion OCXO and you have the best
of 
all.
Digitally  controlling the Rb will cut the cost of the control loop in 
half. 
For $10  in parts and a PC board for less than $10 using Shera like  
controller  can be realized. What is needed is some one able to do  the PIC.
If some one is interested and able, please contact me off list. A  low cost 
 
GPS or a 1 pps output of a Tbolt be perfect source.
Bert  Kehren


In a message dated 1/12/2012 12:20:15 P.M. Eastern Standard  Time,  
lists at rtty.us writes:

Hi

I think it would be  worth the effort to try dithering the  DDS commands 
into
the Rb while  measuring ADEV. You *might* find that you  can do it with  
little
or no impact on the unit's stability. If so it takes  out  some modification
effort and should make the controller cheaper.   

Bob

-----Original Message-----
From:   time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf  Of  EWKehren at aol.com
Sent: Thursday, January 12, 2012 10:43  AM
To:  time-nuts at febo.com
Subject: Re: [time-nuts] FE-5680A  Mechanical  Question

Bringing out the C field in my estimation  does not effect long  or short  
term. External magnetic field I  think is a joke. An other  option is a 
loop 
that  generates a  tuning word for the DDS but that  means your steps are 7
E-13.
Bert  Kehren


In a message dated  1/12/2012 10:34:10 A.M. Eastern  Standard Time,  
davidwhess at gmail.com  writes:

I was   more interested in the technical details of how to  adjust the
output  of a  RbO without sacrificing the short and long  term  stability.
I have seen a  few designs that used a DDS to  generate  the 10 MHz
output which lends  itself to this but they  all suffer from  DDS and
tuning noise.  I see  now that the  RbO can be adjusted  with an external
magnetic field.

On   Thu, 12 Jan 2012 07:34:44  -0600, "J. L. Trantham"    <jltran at att.net>
wrote:

>David,
>
>I have   been  following discussions on the list about a GPSDRbO for a 
year  

or
>so.  Some interesting challenges and probably  best  implemented  in a 
'stable'
>environment rather than  portable  operation but as best I  can tell, it  
would
>require a very  stable and good antenna location,   stable and clean 
power, 

and
>I was thinking of using something  like an  LPRO-101 with  an Ext C Field
>input, a Shera type  controller, and a GPS  timing  receiver, though, I  
suspect
>there are likely to be some   'multi-tasking'  receivers out there that 
will
>look at several  sources   including GPS, GLOSNASS, etc.
>
>While the project  might be  fun,  for portable work, it is likely far 
easier
>and   probably just as good  (almost), to use a Tbolt.
>
>In  any  event, something to think  about for the   future.
>
>Joe
>
>-----Original    Message-----
>From: time-nuts-bounces at febo.com    [mailto:time-nuts-bounces at febo.com] On
>Behalf Of   David
>Sent:  Wednesday, January 11, 2012 11:12 PM
>To:   Discussion of precise time and  frequency measurement
>Subject:  Re:  [time-nuts] FE-5680A Mechanical   Question
>
>
>How  would a GPSDRbO work?  Phase  lock the  DDS output to the GPS? Phase  
lock
>a VCXO to  the GPS and then phase lock  to the RbO on loss  of GPS  lock?
>
>On Wed, 11 Jan 2012 22:55:58  -0600, "J. L.   Trantham"   <jltran at att.net>
>wrote:
>
>>Bill,  Brian,  Bill, and  Peter,
>>
>>Thanks for the  info.   All I need now is a  'project' to incorporate the 
 
>>unit  into.
>>
>>In  the back of my mind, I  have the  thought of a 'box' that will be  
>>battery powered or  110  VAC powered (perhaps with an internal SLA  
>>battery) and   include a GPSDO and Rb unit (possibly a GPSDRbO) for  the  
 
>>purpose of a 'reference' for portable operation in the    microwave    
>>regions.
>
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