[time-nuts] Re: Phase noise of HP8663A 640 MHz reference?

[Richard (Rick) Karlquist]

On 8/21/2022 8:19 PM, Gerhard Hoffmann via time-nuts wrote:
> If you start at 100 MHz, there is a good 400 MHz SAW filter
> < 
> https://www.digikey.de/de/products/detail/qualcomm-rf-front-end-rffe-filters/B39401B3742H110/1858962?s=N4IgTCBcDaIEYGYDsAWCBdAvkA 
>  Â >
> 
> for spurious cleanup at $2 per pop. With 250 KHz BW it cannot do much
> against close-in phase noise but 2 of them back-to-back deliver
> quite clean a carrier at 400 MHz. Even if you just dump a 100 MHz 5V

Actually, if can have a big effect on close in phase noise.  Meaning
it can make it a lot worse, due to the filter's intrinsic flicker noise.
Especially at the $2 price point.

Rick