[time-nuts] Things to look for when buying a few FE-5680A's?

Chris Albertson albertson.chris at gmail.com
Thu Jan 26 12:36:18 EST 2012

On Thu, Jan 26, 2012 at 9:13 AM, Bob Camp <lists at rtty.us> wrote:
> Hi
> If you *need* to lock one of the new FE-5680's 10 or 20 Hz high, you
> probably can adjust the cap on the VCXO center it's range up there.

The frequency division is done by digital logic inside a CPLD and
you'd need to re-program the firmware.  I think people have found that
these new FE5680s don't lock if you move far from 10MHz and you can't
get more than a few hundred Hz from 10Mhz by analog adjustment.

The "option 2" that is in the book is different from the fine scale
adjustment the current $40 can do.   the true option two units can be
programmed over a range of many MHz by sending RS232 commands but the
current units can only by programmed over rs232 withina very narrow
range about like you'd find on a typical OCXO.

I think if you want a wide range oscillator you are best using a DDS
chip whos clock is locked to the FE5680 or a Thunderbolt.   The
FE5680's advantage over a t-bolt is portability.

Chris Albertson
Redondo Beach, California

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