[time-nuts] The 5MHz Sweet Spot

Mike Feher mfeher at eozinc.com
Sat Nov 2 09:50:50 EDT 2013


Exactly - I mentioned this on here about 3 years ago and all of the
self-proclaimed geniuses poo-pooded it.  I was told early in my engineering
career in the early 70's,  by a very smart man, when I thought I had all of
the answers, that considering all of the trade-offs regarding performance,
around 3 MHz for a crystal is best, operating in the 3rd overtone mode,
hence the slow progression from the 1 and 5 MHz standards to 10 MHz. Now,
getting close to 70, I just see what I can learn from all the "smart" people
on here, and keep quiet most of the time. Regards - Mike

Mike B. Feher, EOZ Inc.
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960 office
908-902-3831 cell

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of David McGaw
Sent: Saturday, November 02, 2013 1:30 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] The 5MHz Sweet Spot

This all seems to be forgetting that the crystals are usually operated at
3rd or 5th harmonic.  The crystal in a 10811A is 10 MHz/3rd overtone.  A
high quality 5 MHz/5th overtone crystal is really a 1 MHz fundamental, a
large piece of quartz.  Running at a harmonic greatly reduces the influence
of the package.

David




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