[time-nuts] Keysight N5511A - phase noise measurements down to theoretical-177 dBm/Hz

[Bruce Griffiths]

Its only necessary (as NIST have shown) to cool the splitters to reduce the correlated or anti-correlated noise between the outputs. Everything else can run at ambient temperature. 

Bruce
> On 21 August 2019 at 18:49 ed breya <eb at telight.com> wrote:
> 
> 
> That's quite an impressive system. I guess it's a few generations beyond 
> my 11729C.
> 
> One way to get overall performance to the limits of room temperature kT 
> noise level, is to lower the T where you work. I wouldn't be surprised 
> if some parts are TE-cooled, easily affordable in a big budget system. 
> My first thought was maybe a bunch of stuff in a cryogenic system, but 
> it looks like most pieces are modules in a rack mainframe, and not in a 
> special environment. But, within the modules, I could picture some 
> degree (PTP) of TE-cooling being included, giving some margin on the 
> capabilities.
> 
> Ed
> 
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