[time-nuts] How Rubidiums make their frequency
Dave Brown
tractorb at ihug.co.nz
Wed Apr 19 17:13:08 EDT 2006
----- Original Message -----
From: "Matt Ettus" <boyscout at gmail.com>
To: <K3IO at verizon.net>; "Discussion of precise time and frequency
measurement" <time-nuts at febo.com>
Sent: Thursday, April 20, 2006 7:55 AM
Subject: Re: [time-nuts] How Rubidiums make their frequency
> Since we can now make DDS's with arbitrary frequency resolution,
> could
> you make an Rb oscillator without the magnetic field adjustment?
snip---
I suspect the FEI 5650 series does just that- a 50.255+ MHz VCXO is
'locked' at 1/136 of the 6.8GHz Rb resonance and there is no 'user'
adjustment provided for the physics package. I suspect the magnetic
field IS preset in the factory but thereafter intended to be left well
alone.
The 50.255+ VCXO drives an AD9830-all fine tuning of the output
frequency takes place by setting the DDS.
Can anyone comment further on this?
On a related issue- the physics package in these units draws a
significant current at startup- I'm considering current limiting the
suppy until the current drops back to a lower value-I guess this
delays the warmup somewhat but it would reduce the current required
from the supply to the steady state value, for example, thus allowing
a smaller power supply rating.
But is this a practicable idea and if so, is it likely to have a
detrimental effect on the physics package?
DaveB, NZ
--
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.385 / Virus Database: 268.4.4/318 - Release Date: 18/04/2006
More information about the time-nuts
mailing list