Super stable BVA Quartz resonators... BVA??
Javier wrote:
Anyway, a 10544 oscillator has a cold
offset that can easily be of 1000Hz, so if at 80 deg. C the offset is
zero, and at 25 deg. C the offset is 1000Hz, you easily have a rough
15Hz/deg C average tempco in that range - and the aging drift for this
oscillator is quite less than that.
The 10544A incorporates an AT cut crystal. The tempco is far away from
being linear. From room temp to the oven temperature it follows a 3rd
order parabola, which has its minimum at the oven temperature. This
"trun-over tempearture" varies from unit to unit, which means that the
slope of f(T) also changes form unit to unit.
Not the best approach for measuring temperatures ;-)
At the other hand, the current consumption of the 10544A decreases
fairly linear with temperature, so this is a better (but rather slow)
temperature sensor, which would even work without the quartz...
Regards
Bernd
DK1AG
DK1AG wrote:
... the 2801A has a special
connector for it. It looks like a smaller version of a BNC connector,
but the bayonet has three "nipples" instead of two. Does anyone on the
list know what kind of connector that is and where to get the
counterpart (plug)?
Regards
Bernd
DK1AG
Bernd,
may you send me a picture of the connector?
Direct email <ik1odo at spin-it.com>
73 - Marco IK1ODO / AI4YF
-----Original Message-----
From: time-nuts-bounces@febo.com
[mailto:time-nuts-bounces@febo.com] On Behalf Of Bernd T-Online
Sent: Sunday, December 09, 2007 8:44 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA??
Not the best approach for measuring temperatures ;-) At the
other hand, the current consumption of the 10544A decreases
fairly linear with temperature, so this is a better (but
rather slow) temperature sensor, which would even work
without the quartz...
See what current versus temperature looks like:
http://www.ko4bb.com/Test_Equipment/HP10811-Current.png
Didier KO4BB
Berndt I believe you are describing a "Triax" connector I found them through
Trompeter but I believe they are sold by Farnell and RS Components in the
UK. The same connector was used I think on some of the HP system digital
voltmeters.
Cheers de Alan G3NYK
----- Original Message -----
From: "Bernd T-Online" BNeubig@t-online.de
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Sunday, December 09, 2007 2:21 PM
Subject: Re: [time-nuts] Super stable BVA Quartz resonators... BVA??
Tim Shoppa wrote:
For a while, didn't HP sell temperature probes which were in fact
quartz crystals? Oscillation frequency was converted by some simple
electronics to a temperature, and at the time (60's?) they were
exquisitely convenient for measuring way better than a tenth of a
degree.
Either the frequency drift was negligible or it
was so slow that I don't remember any manual removal of frequency
drift effects.
I'm guessing the probe crystals were some special cut (don't know
which!)
which was fairly linear or at least monotonic over the measurement
temperatures. I'm guessing that HP chose a cut which had a very large
tempco such that tempco dominated over any frequency drift.
They did indeed. This was the HP2801A, later followed by the HP2804A.
It uses a so-called LC-cut (Linear Coefficient) quartz crystal sensor,
which is a doubly rotated cut with ultra-linear frequency vs.
temperature characteristic with a slope of 35.4 ppm/K.
For more information see http://hparchive.com/Journals/HPJ-1965-03.pdf
BTW: I proudly own a HP2801A plus two crystal sensor elements. However I
cannot connect them to the instrument, because the 2801A has a special
connector for it. It looks like a smaller version of a BNC connector,
but the bayonet has three "nipples" instead of two. Does anyone on the
list know what kind of connector that is and where to get the
counterpart (plug)?
Regards
Bernd
DK1AG
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Yes, but that doesn't account for this part of his request
(emphasis added):
"It looks like a smaller version of a BNC connector,
but the bayonet has three "nipples" instead of two."
-Chuck Harris
Alan Melia wrote:
Berndt I believe you are describing a "Triax" connector I found them through
Trompeter but I believe they are sold by Farnell and RS Components in the
UK. The same connector was used I think on some of the HP system digital
voltmeters.
Cheers de Alan G3NYK
Marco IK1ODO wrote:
may you send me a picture of the connector?
Direct email <ik1odo at spin-it.com>
Thanks, Marco. I have the unit in my QRL lab, so I can take a photo only
by tomorrow.
Regards
Bernd
DK1AG
Yes, I know... I was only exposing it as an example of how the
temperature coefficient can be quite higher compared with the aging
effect even if the quartz crystal is not intended to be used as a
temperature sensor :)
Regards,
Javier
Bernd T-Online escribió:
Javier wrote:
Anyway, a 10544 oscillator has a cold
offset that can easily be of 1000Hz, so if at 80 deg. C the offset is
zero, and at 25 deg. C the offset is 1000Hz, you easily have a rough
15Hz/deg C average tempco in that range - and the aging drift for this
oscillator is quite less than that.
The 10544A incorporates an AT cut crystal. The tempco is far away from
being linear. From room temp to the oven temperature it follows a 3rd
order parabola, which has its minimum at the oven temperature. This
"trun-over tempearture" varies from unit to unit, which means that the
slope of f(T) also changes form unit to unit.
Not the best approach for measuring temperatures ;-)
At the other hand, the current consumption of the 10544A decreases
fairly linear with temperature, so this is a better (but rather slow)
temperature sensor, which would even work without the quartz...
Regards
Bernd
DK1AG
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
At 17.58 09/12/2007, Bernd wrote:
Thanks, Marco. I have the unit in my QRL lab, so I can take a photo only
by tomorrow.
Ok, good. There are triax connectors with three and two bayonets
around - ask Keithley... they have used both types.
Or it may be something else, HI.
73 - Marco IK1ODO / AI4YF
At 3:21 PM +0100 12/9/07, Bernd T-Online wrote:
BTW: I proudly own a HP2801A plus two crystal sensor elements. However I
cannot connect them to the instrument, because the 2801A has a special
connector for it. It looks like a smaller version of a BNC connector,
but the bayonet has three "nipples" instead of two. Does anyone on the
list know what kind of connector that is and where to get the
counterpart (plug)?
Regards
Bernd
DK1AG
Bernd,
That is a real oddball connector. I encountered one inside a surplus
trunk-mount Motorola car telephone made in the 1970s.
The only submini bayonet connectors I find mentioned with Google are
the Kings KM which is like the BSM which Tektronix used, and Google
gives a photograph. It has two bayonet pins.
Unfortunately, if no one makes it anymore, data will be hard to find,
much less the actual connectors.
--
--David Forbes, Tucson, AZ
http://www.cathodecorner.com/