[time-nuts] Cheap 9.8Mhz Sa.22c's

[Bob Camp]

Hi

9.3804 MHz = (2^15*3) * 100 Hz

10 MHz = 2^5 * 5^5 * 100 Hz

With a normal integer PLL, your highest lock frequency would be 2^5* 100 Hz = 3200 Hz.

Bob

On Jun 2, 2013, at 3:52 PM, WB6BNQ <wb6bnq at cox.net> wrote:

> Hello Mark and crowd,
> 
> I own one of these and I can guarantee that it CANNOT be moved without changing the crystal, tweaking a
> micro-minature coil value, and changing the firmware.  And NO !, the company would NOT send out the firmware
> needed.  However, if you wanted to spend between $500 and $1000 they would fix it for you.
> 
> While there is a DDS inside, it and the crystal are part of Rubidium frequency locking loop.  The actual output
> frequency is generated by dividers in a big ASIC/FPGA/whatever device.  YES, that output frequency is derived from
> the crystal frequency.
> 
> They start by choosing a output frequency which selects the crystal frequency.  The crystal is multiplied up to some
> frequency and mixed with the output of a DDS (also driven by the crystal) to produce the final frequency multiplied
> further to get to the Rubidium resonance.  So, without a change in the firmware, there is no way to tweak the unit
> more than a very small amount.
> 
> BUT all is not lost.  The 9.8304 MHz frequency is related to the common RS-232 modem frequencies.  It is also
> related to the common sound card frequency of 24.576 MHz.  There it is possible to phase lock it to 10 MHz.
> 
> Bill....WB6BNQ
> 
> "Mark C. Stephens" wrote:
> 
>> These are 9.8304Mhz, is possible to move them to 10Mhz?
>> 
>> http://www.ebay.com/itm/Symmetricom-SA-22c-9-8304MHz-Precision-Rubidium-Oscillator-5V-and-15V-NICE-/261223397404
>> 
>> -marki
>> 
>> Kind Regards,
>> Mark Stephens
>> 
>> Mark Clemens Stephens | Customer service engineer | Non-Stop Computer Ltd
>> * +61 2 9011 8186 | ( +61 428 256 334 | * marks at non-stop.com.au<mailto:marks at non-stop.com.au>
>> 
>> Non-Stop Computer PTY LTD
>> 79 Devon St
>> North Epping
>> NSW 2121
>> Australia
>> Timezone: AEST (UTC +10)
>> 
>> Email: service at non-stop.com.au<mailto:service at non-stop.com.au>
>> 
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>