Those switch mode regulator modules under the finned heatsinks in the
Z3815A are likely responsible for most of the spurs.
The ECL/CML logic dividers and the various ouputs like 19.6608MHz also
contribute.
Since the E1938A output is only +4dBm, its very easy to degrade the
phase noise in the buffer chain if one isnt careful.
With careful design a discrete buffer amp phase noise floor below
-170dBc/Hz should be possible with a + 4dBm input.
Bruce
[email protected] wrote:
Not necessarily so..
My HP Z3815A here (desktop unit) has horrible phase noise and massive
spurs. Really to cry over since I know what the internal OCXO (1938A type) is
capable of generating.
See the attached plot.
bye,
Said
In a message dated 11/26/2010 16:37:26 Pacific Standard Time,
[email protected] writes:
So if I want a really souped-up freq standard for my lab, then I should
concentrate on finding the best oxco I can (which may be disciplined by
the
GPS or manually occasionally calibrated to GPS), and use the best power
supply I can find. These seem to be what I should concentrate on rather
than more channels.
I do believe that I read some stuff on the internet that the HP GPS DO's
do
seem to have very good power supplies (or converters) which contribute to
low spurs. So it seems the HP's do have a real advantage (not just the
name).
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