[time-nuts] ext ref LNB Re: ADEV

[jimlux]

Mike Feher wrote:
> Well, that I do not know. The majority of Ku & Ka LNBs for home TV use are
> using free running DRO's. I have a bunch of them, and never ran across any
> locked ones, except for some of the ones used for internet service. My real
> experience is what we use in military satcom terminals at Ku and Ka bands,
> with apertures from 0.6 to 9.2 meters, and they are all locked to an
> external 10 MHz reference. I doubt if you will see any major dumping of
> those. Especially now, because of strict ITAR. Even if one can buy it
> directly from the manufacturer, once the military has owned it, they will
> probably dispose of it in such a way that we will not see them on ebay.
> Regards - Mike


I doubt the LNB is export controlled.. It's unlikely to have an 
exotically low noise temperature, they're not cryogenic, they don't use 
components with dual-use, it's just part of a receiver.  If you go to 
the NORSAT website, for instance, they don't make much mention of export 
controls  (yeah, I'm sure the invoice/quote would have export 
boilerplate on it "the contents of this have not been reviewed... use, 
sale, distribution may require license...")

http://www.norsat.com/lnb/blog

And I note that the datasheet's pretty sketchy on the external reference 
LNBs.. They give phase noise as follows (for Ku band, 10.75 GHz LO):
-75dBc/Hz @ 1kHz
-85 @ 10k
-95 @ 100k

But they don't say whether that's added to the reference noise, or 
that's the "outside the loop" noise, or what..

What's interesting is that the Ka-band LNB (for 18-19 GHz, which is low 
Ka, to my thinking.. I think 30 when I think Ka).. the noise is actually 
lower
-65 @ 1k
-75 @ 10k
-95 @ 100k
-100 @ 1M