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

[Bob Camp]

Hi

There are an enormous number of variations on the basic SC trap. Most of
what drives one to be “best” is the component selection process. If a coil above
X uh simply will not fit, time for a new circuit ….

Bob

> On Jul 19, 2015, at 12:53 AM, jerry shirᴀr <radio.n9xr at gmail.com> wrote:
> 
> 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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> <5MHz SC trap.png>_______________________________________________
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