[time-nuts] FE-5680B Rubidium and DDS

Clint Jay cjaysharp at gmail.com
Sat Sep 26 06:13:26 EDT 2015


The 10MHz output comes from the XC9572 CPLD but the fact that it's there
for a few seconds makes me thing it's possible to recover it, by fair means
or foul.

It's possible it's just a gate, certainly looks like it's bing switched off
and there's a file which claims to be a dump of the CPLD (as well as a few
other binaries) so it may be possible to trace it back but I'd want to try
and dump the CPLD contents from my FE so I'm going to build a JTAG cable.

The other option which may be more practical would be to add my own DDS
(already designed and built for another application but would need to be
modified a little and repackaged) and use the 30MHz CPLD output that's
always present when the unit is locked to get programmable spot
frequencies.

On 26 September 2015 at 07:40, Hal Murray <hmurray at megapathdsl.net> wrote:

>
> > I as well wish there was a quick way of converting it back to 10Mhz. I am
> > sure it can be done, just not sure how or where to look
>
> If the 10 MHz is visible for a second or two, there is probably a gate to
> turn it on/off.  If I wanted 10 MHz, I'd open it up and trace the wire
> back.
> If it goes to a gate, you might be able to lift the pin for the other input
> and wire it hi/low.  There is a good chance it goes to a FPGA where you
> can't
> get at the gate.
>
>
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
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-- 
Clint.

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