A couple of comments about the PTS units...
While the potential noise floor is very low (depending on the quality of
the reference oscillator), there can be significant spurs depending on
how many non-zero digits you have dialed in. With the analog multiply
and mix architecture, the more digit stages are in use, the more spurs
you get above the low noise floor.
The lower frequency units tend to have better noise than the ones with
higher frequency ranges. The PTS X10, 040, and 160 models are the
quietest if you can live with their upper frequency limits (10, 40, and
160 MHz respectively).
There's also one very tricksie version out there that is particularly
interesting for time-nuts -- the PTS250/SX51 where the SX51 option is a
switchable divider that turns a 250 MHz synthesizer with 1 Hz resolution
into a 25 MHZ synthesizer with 0.1 Hz resolution, and a significant
phase noise improvement. Its noise floor is around -145 dBc/Hz, while
the other units are in the -125 to -135 range.
I have a bunch of measurements of PTS boxen at
https://febo.com/pages/pts_synth/
(And, I'm getting ready to sell a few of the too-many PTS boxes in my
lab, including an SX51... look out for a notice in the next week or so.)
John
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On 3/7/19 7:15 PM, Alex Pummer wrote:
that is a relative low noise synthesizer
Programmed Test Sources PTS 160 Frequency Synthesizer
73
Alex
On 3/7/2019 11:04 AM, Richard (Rick) Karlquist wrote:
On 3/7/2019 8:56 AM, Didier Juges wrote:
The king of low close-in noise are the HP8662 (990MHz) and HP8663
(2GHz?)
by about 20dB at 1kHz compared to the 8644A
Didier KO4BB
When I worked at Agilent, my lab had a half dozen HP8662's and some
63's. They were not useful for any kind of high performance clock
requirement, unless we divided them down with, for example, a
Centellax (now Microchip) divide by 8 to 511 eval board. That was SOP
in those days.
If you just want 100 MHz, there are inexpensive 100 MHz VCXO's
(about $25 at D/K or Mouser) that will blow the doors off of
an HP signal generator. You can phase lock them to a 10 MHz OCXO
if necessary. Besides 100 MHz, there are various other frequencies
available. See Crystek and Abracon, etc. These VCXO's put out
CMOS logic signals, so you have to convert sine to square.
Rick N6RK
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