Good afternoon,
It comes as no big surprise that ultrastable oscillators has
double-isolation both on thermal and power-supply sides. Both being
important environmental noise injection paths for any oscillator, moving
the operating points of transistors about.
Long-term systematics is indeed something to look at. We've had long
discussions on thermal stability before.
Cheers,
Magnus
On 07/19/2015 02:19 PM, KA2WEU--- via time-nuts wrote:
Good morning,
That is too close for my taste. For long term stability, 1 Hz and less the
transistor has more influence then considered . It is a pity that this
group does not address this topic.More to come. I am supervising a PhD
dissertation and it became clear that that is an issue
Ulrich N1UL
In a message dated 7/19/2015 8:12:44 A.M. Eastern Daylight Time,
[email protected] writes:
I am attaching a file showing the schematic for the trap used in a
Colpitts
oscillator which will look like 58pF at 5MHz and will be inductive at
5.5MHz. So something like this can be used in place of a pair of one of
the split capacitors at ~56pF loading the crystal.
Jerry N9XR
On Sat, Jul 18, 2015 at 11:59 AM, Magnus Danielson <
[email protected]> wrote:
Dear Ulrich,
Now you taught me something useful, that the SC-cut has inherent less
noise than AT-cut. Many thanks.
Indeed, measuring below 1 Hz starts to be challenging as environmental
aspects chimes in. I assume you ovenize your crystals, to make use of
the
turn-over point.
Even for ovens, (wind)shielding to reduce thermal stress turns out to be
helpful. Some toss their oscillators into thermal flasks too. As always,
a
myriad off issues creep up as you push the noise down and want to verify
it. Thermal mass has proven useful in many ways. There was a nice paper
from NIST where they used water-bottles to stabilize WWVB.
Cheers,
Magnus
On 07/18/2015 11:52 AM, KA2WEU--- via time-nuts wrote:
Good morning,
the AT Cut is inherently noisier then the SC cut but the SC has some
spurious resonances modes. Measurements below 1 Hz are very tricky as
the
oscillator must be (more or less) insulated from hum, infrared (heater)
. Here I
am still struggling .
Ulrich N1UL
In a message dated 7/17/2015 9:59:55 P.M. Eastern Daylight Time,
[email protected] writes:
He doesn't mention that that crystal is used in New Horizons:
http://www.bliley.com/products/crystals-precision-standard/vacuum-sealed/
Nice. I have a similar crystal from Valpey-Fischer, 5 MHz 5th
overtone
AT-cut (as opposed to your 3rd overtone SC-cut). I would be interested
in what you would use for an oscillator circuit.
David N1HAC
On 7/17/15 4:27 PM, paul swed wrote:
Ulrich,
Nice picture. What are you doing with the crystal? I have several
older
crystals that are nice but have never done anything with them.
Regards
Paul
WB8TSL
On Thu, Jul 16, 2015 at 6:02 PM, KA2WEU--- via time-nuts
<[email protected]
wrote:
I am working with this ...... amazing device, Ulrich N1UL
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