On 6/2/13 12:52 PM, WB6BNQ 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.
You mean bit clock, not modem, I think.. 9.8304 M = 512 * 19.2 k so you
can make all those baud rates down to 300 baud/sec. I don't think you
can get 110 bps, but you could even Rb lock your old ASR33 by dividing
down to 60 Hz (it evenly divides to that) and running the synchronous
motor off that.
That 24.576M sound card is at 2.5x
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