[time-nuts] 5 x 2 x 3 = 30 MHz

Magnus Danielson magnus at rubidium.dyndns.org
Sat Jul 18 16:59:55 UTC 2015


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,
> n1hac at dartmouth.edu 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
> <time-nuts at febo.com
>>>   wrote:
>>>
>>> I am working with this ...... amazing device,  Ulrich N1UL
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