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

KA2WEU at aol.com KA2WEU at aol.com
Sun Jul 19 08:19:48 EDT 2015


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,  
radio.n9xr at gmail.com 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  <
magnus at rubidium.dyndns.org> 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,
>>  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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