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.
John
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