I see what you mean...I guess it comes out as a wash, but I will try to
explain what I meant. Phase noise degrades by
[20log(N)], where N is your division ration in the feedback network of the
PLL. Dividing it down improves the phase noise by the inverse of the
aforementioned formula. If phase noise is looked at as an FM signal that has
a certain deviation bandwidth, it becomes apparent that when the carrier
frequency is divided down, the modulation sidebands (phase noise) are
divided down by the same proportions.
The main advantage with Palstar's scheme is that by designing the system at
a higher frequency, a higher reference frequency can be used. This allows a
faster settling time for the system. Once everything is divided down, you
now have a system with finer tuning steps, quicker settling time, and
roughly the same phase noise.
I must have been sleeping when I made that comment about the phase
noise..........thanks for waking me up!
Too many things on my mind!

Pete

"Telamon" wrote in message
...
In article ,
"Pete KE9OA" wrote:

They are both very good sounding receivers. Both of them sound very
similar,
with the HF-150 sounding slightly better. Sensitivity is about the same,
with the R30 having better dynamic range. Whereas the selectivity in the
Lowe receivers is obtained through the use of more inexpensive Murata
CFWS
6-element ladder filters, the R30 uses either high grade 11-element
filters
or mechanical filters. The exception is the SSB bandwidth; both of the
receivers use 11-element filters.
The Lowe receivers use a 45 to 75MHz VCO for the synthesizer while the
R30
uses a 360 to 600MHz VCO and divides it by 8 to obtain the 45 to 75MHz
LO.
The advantage here is that the phase noise is divided down by the
division
factor.

Snip

Hi Pete. Nice post as usual from you on the technical aspects of radio
receivers.

I don't understand how dividing down a synthesized clock by itself
reduces the phase noise unless the divider is filter for the phase noise?

--
Telamon
Ventura, California