Re: [time-nuts] need recomendation for a portable 10mhz reference oscilator
In a message dated 12/13/2007 09:58:04 Pacific Standard Time,
dforbes@dakotacom.net writes:
oscillator. You could slip it into a pocket you would sew in your
long johns in the armpit or groin area. That should keep it
toasty-warm at all times.
Hi David,
that HP puck runs it's crystal at over 100 Degrees C, and the enclosure
temperature of a typical OCXO gets to above 60C in still air.
They also have Tantalum caps, and anyone who has seen a fiery Tantalum cap
explosion knows these things can be very dangerous.
You may wake up dead, or castrated.
I would not put that thing near my groin if I were you!
bye,
Said
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SAIDJACK@aol.com wrote:
Hi David,
that HP puck runs it's crystal at over 100 Degrees C, and the enclosure
temperature of a typical OCXO gets to above 60C in still air.
They also have Tantalum caps, and anyone who has seen a fiery Tantalum cap
explosion knows these things can be very dangerous.
You may wake up dead, or castrated.
I would not put that thing near my groin if I were you!
bye,
Said
Said
The E1938A oven has exceptionally high thermal gain so variations in the
OCXO frequency due to ambient temperature changes may well be insignificant.
Before proposing drastic/dangerous measures David should attempt to
measure the E1938A frequency variations as a function if temperature to
see if the frequency change is actually significant.
Making such a measurement is likely to be an extremely
difficult/challenging task. Even so measurement beats speculation
everytime.
Bruce
I have heard rumors of a U.S. Army program to develop a "suppository
oscillator." I don't recall any details, though.
-RL
Robert Lutwak
Symmetricom - Technology Realization Center
RLutwak@Symmetricom.com (Business)
Lutwak@Alum.mit.edu (Personal)
(978) 232-1461 (Desk)
(339) 927-7896 (Mobile)
(978) 927-4099 (Facsimile)
----- Original Message -----
From: SAIDJACK@aol.com
To: time-nuts@febo.com
Sent: Thursday, December 13, 2007 5:11 PM
Subject: Re: [time-nuts] need recomendation for a portable 10mhz
referenceoscilator
In a message dated 12/13/2007 09:58:04 Pacific Standard Time,
dforbes@dakotacom.net writes:
oscillator. You could slip it into a pocket you would sew in your
long johns in the armpit or groin area. That should keep it
toasty-warm at all times.
Hi David,
that HP puck runs it's crystal at over 100 Degrees C, and the enclosure
temperature of a typical OCXO gets to above 60C in still air.
They also have Tantalum caps, and anyone who has seen a fiery Tantalum cap
explosion knows these things can be very dangerous.
You may wake up dead, or castrated.
I would not put that thing near my groin if I were you!
bye,
Said
**************************************See AOL's top rated recipes
(http://food.aol.com/top-rated-recipes?NCID=aoltop00030000000004)
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From: Bruce Griffiths bruce.griffiths@xtra.co.nz
Subject: Re: [time-nuts] need recomendation for a portable 10mhz reference oscilator
Date: Fri, 14 Dec 2007 11:22:52 +1300
Message-ID: 4761B0BC.5080303@xtra.co.nz
The E1938A oven has exceptionally high thermal gain so variations in the
OCXO frequency due to ambient temperature changes may well be insignificant.
Before proposing drastic/dangerous measures David should attempt to
measure the E1938A frequency variations as a function if temperature to
see if the frequency change is actually significant.
Making such a measurement is likely to be an extremely
difficult/challenging task. Even so measurement beats speculation
everytime.
Why would it be very hard? For his purpose it should easy enought to measure
the frequency shift which he would allow, and achieving the necessary shift in
temperature to get the ball-park aspect should not be too hard to acheive in a
home enviorment and a thermometer.
I am sure the E1938A would pull it off.
Talking about E1938A. Where can I find one???
Cheers,
Magnus
The E1938A oven has exceptionally high thermal gain so variations in the
OCXO frequency due to ambient temperature changes may well be insignificant.
Before proposing drastic/dangerous measures David should attempt to
measure the E1938A frequency variations as a function if temperature to
see if the frequency change is actually significant.
Making such a measurement is likely to be an extremely
difficult/challenging task. Even so measurement beats speculation
everytime.
Bruce
Bruce,
Perhaps then this trick should be used with an ovenized oscillator of lesser quality,
since it sounds like the E1938A will work just fine if stuck in the snow.
Not that I have one on hand to test, anyways.
David Forbes wrote:
Bruce,
Perhaps then this trick should be used with an ovenized oscillator of lesser quality,
since it sounds like the E1938A will work just fine if stuck in the snow.
Not that I have one on hand to test, anyways.
David
Putting an OCXO in your pocket may cause problems with
vibration/movement modulating the OCXO frequency.
Maybe you should stick an accelerometer in you pocket and measure the
the resultant acceleration likely to be experienced by the OCXO.
Failing that stick the OCXO in you pocket and see if its stability is
significantly degraded.
You will find that something in a more rugged case like an FTS1200 is
both cooler and safer (exploding parts should remain inside the housing).
Bruce
Magnus Danielson wrote:
Why would it be very hard? For his purpose it should easy enought to measure
the frequency shift which he would allow, and achieving the necessary shift in
temperature to get the ball-park aspect should not be too hard to acheive in a
home enviorment and a thermometer.
I am sure the E1938A would pull it off.
Talking about E1938A. Where can I find one???
Cheers,
Magnus
Hej Magnus
The test sheet on a typical (sample size of 1) E1938A test sheet states
among other things
Max slope near 0.T, 0 mHz/degree. (ie tempco < 1E-13/degree)
So in practice, depending on what equipment is available, the
measurement of the frequency change is likely to be extremely challenging.
At best it may be possible to state that the frequency change is less
than 1E-11 (substitute actual measurement resolution/accuracy limits).
For an E1938A try bidding on one of the Australian sourced Z3815A's
that keep popping up on ebay (however bids are relatively high).
Bruce
----- Original Message -----
From: "Bruce Griffiths" bruce.griffiths@xtra.co.nz
To: "Discussion of precise time and frequency measurement"
time-nuts@febo.com
Sent: Thursday, December 13, 2007 6:08 PM
Subject: Re: [time-nuts] need recomendation for a portable 10mhz reference
oscilator
Magnus Danielson wrote:
Why would it be very hard? For his purpose it should easy enought to
measure
the frequency shift which he would allow, and achieving the necessary
shift in
temperature to get the ball-park aspect should not be too hard to
acheive in a
home enviorment and a thermometer.
I am sure the E1938A would pull it off.
Talking about E1938A. Where can I find one???
Cheers,
Magnus
Hej Magnus
The test sheet on a typical (sample size of 1) E1938A test sheet states
among other things
Max slope near 0.T, 0 mHz/degree. (ie tempco < 1E-13/degree)
So in practice, depending on what equipment is available, the
measurement of the frequency change is likely to be extremely challenging.
At best it may be possible to state that the frequency change is less
than 1E-11 (substitute actual measurement resolution/accuracy limits).
For an E1938A try bidding on one of the Australian sourced Z3815A's
that keep popping up on ebay (however bids are relatively high).
Bruce
For those that wanted the HP "hockey puck" oscillator, one is one ebay now
but is closing in hours. GPS Locked, 10 MHz Frequency Standard, HP
Z3815A/E1938A http://search.ebay.com/330196691921
The man apparently had two of these units, the first one sold for 1725.00,
this one is up to 1005.00 now. It would make a nice Christmas present !