[time-nuts] FE-5680A Rubidium Pinout again

Jan Fredriksson jan at 41hz.com
Thu Jan 10 09:40:57 EST 2008

Hi time-nuts,

It's an amazing list you have here! I had no idea! A new world to me.
I am new here and this is my first posting.

I recently got one of the Ebay FE-5680A units, originating 
from a Motorola telecom board, without a coax out.
I do not even have the Motorola board so there is little to 
start with.

I fund some postings on the FE unit, most from 2005, 
here on in the time-nuts list.

Did any of you make any progress with this unit and the 
pinout and communicating with it?  I'd prefer not to fry the 
thing right from the start..... 

I have opened the lid and found that my unit has a RS232
chip, Sipex SP233ACT. There is also a small internal 
5 pin connector on the PCB, connected to the RS323 
chip Rx/Tx and +5V.

I can trace the front panel 9-pin connector pin 1 / power in
to the onboard VR and pin 2 is ground.  

The unit has and a AD9830A DDS for frequency synthesis. 
In the product sheet for the FE-5680A it's mentioned that the 
unit can be factory programmed to wanted frequency. A good
guess is that it's  via this PCB port as RS232 is not available 
on the front panel connector as far as I can find.

There are also two pushbuttons on one PCB. 
I have seen mentioned in the datasheet that it's for trimming 
the frequency. 

Well, any input would be highly appreciated. I have searched 
the net for all docs I could find but nothing very useful so far.

I will be happy to share my findings if someone is interested.

Neo-Timer Jan 

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