A crystal running in 7th overtone mode has a narrow little resonance
surrounded by other resonances (the 9th and 5th) which must be filtered out.

A crystal running in fundamental mode has a pronounced resonance, with
no other significant resonances until you get to three times the
operating frequency.

If there's anything "wrong" with that circuit it's most likely that the
frequency selective elements to keep it from jumping to 89 or 161MHz.
It may also deliver more feedback to the crystal than absolutely
necessary (dunno about that). So if anything is bad about it it's just
that it has too many components.

It's probably a very good place to start, and should work as-is if you
get the tank tuned right.

Mario Bros wrote:

Hi Mike, thank you.
I am not sure that the circuit is good also for the type of crystal that I
have.
That one used in this plan is a 7th while the mesa it is a fundamental AT.

73's de IK6GQC Rocco

"Michael St. Angelo" ha scritto nel messaggio
...

Here is a low phase noise oscillator circuit for a Analog Devices AD9850
DDS:

http://www.analog.com/UploadedFiles/...13367an419.pdf

73,

Mike N2MS



"Mario Bros" wrote in message
. it...

Hi folks,
I have acquired of the MESA Quartz Crystals to approximately 160 Mhz
fundamental AT.
Someone knows some circuit for their use?
73's de IK6GQC Rocco








--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com