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

[WB6BNQ]

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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