[time-nuts] Strange oscillations

Daun Yeagley daun at yeagley.net
Sat Sep 4 10:17:44 EDT 2004

I suspect your theory about the anti spam filters might be
correct.  John has recently upgraded the server and the spam
and anti-virus filters are much more effective.
Unfortunately, as you know they tend to reject some
legitimate stuff.  He usually scans over the "trappings"
every few days or so and tries to correct the mistakes the
filters have made.  He may have just found yours and
"whitelisted" you.  He has had to do that on a few of my
regular contacts.


-----Original Message-----
From: time-nuts-bounces at febo.com
[mailto:time-nuts-bounces at febo.com]On
Behalf Of Alberto di Bene
Sent: Saturday, September 04, 2004 10:06 AM
To: time-nuts at febo.com
Subject: Re: [time-nuts] Strange oscillations

   Hmmm, my test message passed through, so I dare to resend
this message
   of yesterday, which was
   discarded by the list server. Let's see if this time it
will make it.
     thanks for your advices. And let's hope this message
gets through
   the anti-spam and anti-virus filters
   of the time-nuts list server. At least a couple of my
past messages of
   yesterday didn't make it.
   Maybe usa.net (my mail provider) isn't regarded as a
dependable one.
   Yes, there are other tests I have done that confirm my
   Firstly, from the specs of the Isotemp
   OCXO it's possible to compute that for a change in
frequency of 2E-11
   (approximately what it is possible
   to see on the graph of my first message) it is sufficient
a change in
   temperature of 0.18 degrees Celsius !
   Which can well be in the hysteresis band of the oven
   temperature controller.
   Secondly I graphed about 24 hours, and it was clearly
possible to see
   the periods when I was in the room...
   Maybe just for the fact of being there I moved enough air
to change
   sligthly the temperature. The OCXO
   is not yet closed in the box that will finally contain
the project, it
   is still exposed to the ambent air.
   The Isotemp OCXO-134 was bought on eBay a couple of years
ago, from a
   Korean guy. Apparently it was
   new, no traces of soldering on the wires coming out. But,
annoying as
   it may be a cycling up and down
   of a few units per 1E-11, nevertheless I think it can be
   at least for the more common tasks.
   I have a Z3801A coming in about one month, and I will use
it for the
   more stringent needs.
   You are the second person suggesting me to measure the
oven current,
   and it looks like a good suggestion.
   With the hope that the curent changes will be detectable
with a
   73  Alberto  I2PHD
   Robert Aurand wrote:

This could very well be due to a small oscillation in the
proportional heater c
ontol circuit, as you say.   I've seen it many times before
in OCXO's.   One te
chnique we used to use in production to confirm this was to
monitor the oven cu
rrent simultaneously with the frequency.   Then overlay
graphs of the two quant
ities using the same time scale.   Excel works great for
this.   You may need t
o increase/decrease the scale of one quantity as needed.

Where did you get this OCXO?   A friend recently bought some
OCXO's  of differe
nt manufacture from EBAY.   At first they seemed OK but
every one eventually ha
d jumps.   Most likely they were pulled from equipment for
this reason.

time-nuts mailing list
time-nuts at febo.com

More information about the time-nuts mailing list