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

Rex rexa at sonic.net
Thu Jan 10 14:42:52 EST 2008

Here is a link to an earlier reply to a similar question.

In that message there is a link to another earlier message that has the 
actual pin-out that works for the FE-5680A's that were available in 
2005. I have never heard any reports of anyone finding a way to adjust 
the frequency output on this model. There are other versions that do 
respond to rs232 commands.

So, try the unit with just 15V feeding it. If it gives an output, you 
are lucky and the unit is one that has been found to respond to rs232 
commands. If no output, add the +5 V connection described in the 
messages. You will probably then get 10 MHz on the appropriate pin but 
nobody that I know of has found a way to adjust them.

Jan Fredriksson wrote:
> 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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