[time-nuts] FE5680A

WB6BNQ wb6bnq at cox.net
Tue Mar 6 03:32:50 UTC 2012


Sam,

As far as the 1pps is concerned, it is only 1 microsecond in width.  So, I doubt
you are going to see it on the LED without a pulse stretcher as that is too fast
for your eyes.  Use a one shot to lengthen the pulse to at least 1/2 second.

The RS-232 is used to command very small frequency adjustments to the Rb.
However, to see any return information you must command it to tell you
something.  If you need a reference manual on it let me know and I will send it.

Bill....WB6BNQ


Sam Reaves wrote:

> Hello Group,
>
> I just bought four of the FE5680A's that have the standard configuration
> Pin 1+15, Pin 2 Gnd, Pin 3 Lock, Pin 4 +5V Pin 5 Gnd, Pin 6 1pps?, Pin 7
> 10MHz, Pin 8 TX, Pin 9 RX.
>
> I have a LED with a 330 ohm current limiting resistor on pin 3 (the
> 74ACT240 can sink up to 24mA and I am well below that) for the lock
> indicator. All of my units lock and produce 10MHz although the 1pps never
> switches.
>
> I can not get any of the units to communicate using the DB-9 connections. I
> scoped the receive data into the unit all the way to the microcontroller.
> The RS232 and TTL levels for the data look perfect as well as the timing
> for 9600-N-8-1. However the unit never transmits any data.I scoped this all
> the way to the micro as well. Not a pulse spike or anything.
>
> Has anyone determined what the second serial interface is for? It seems to
> me that it would not make any sense for FE to install the RS232 port if it
> could not be used.
>
> Any hints?
>
> Thanks
> Sam
> W3OHM
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