[time-nuts] Low-Cost Rubidium Performance

John Ackermann N8UR jra at febo.com
Thu Feb 9 13:30:14 UTC 2012

On 2/9/2012 4:56 AM, Alberto di Bene wrote:
> On 2/9/2012 3:36 AM, John Ackermann N8UR wrote:
>> As threatened, I've measured stability (out to a trustworthy 10K
>> seconds) and phase noise of the three popular telecom surplus Rb
>> standards.  I looked at two units of the FE-5680, two units of the
>> Efratom FRS, and one Datum LPRO.
> Which variety of the FE-5680A did you measure ?
> That with the output frequency adjustable in a wide range, with a master oscillator at 52..ish MHz,
> or the latest one, derived from a 60 MHz oscillator, where you can just tweak the output frequency
> with commands to the DDS ?
>  From what I read in this group, they should have quite different phase noise performance.

Good point... I had meant to mention that but just forgot.  These are 
both the recent inexpensive units that came mounted on a large piece of 
PCB and require 5V as well as 15V, so presumably the newer DDS versions.

By the way, I didn't attempt to adjust the frequency of any of the units 
-- I just powered them up and measured as they were.  The two FRS units 
had an external C-field pot attached to the connector, and who knows 
where it was set.


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