[time-nuts] Question about the FE-5680A

[Sidney Cadot]

Hi all,

I recently bought a second-hand FE-5680A for some light
experimentation via ebay.

There seems to be a number of variants floating around. Mine in
particular lacks a J2 (where I would expect to see the 10 MHz
connector), so I only have the DB9 J1 connector.

The unit is working, If I supply 15V over DB9 pins 1/2, the unit heats
up, after a while pin #3 drops to indicate a lock, and pin 6 shows a 1
microsecond wide PPS that I am happy to see, since that is what I am
most interested in.

I have a few questions:

* Does anyone else have a unit that lacks a J2 10 MHz output? Is the
intention of such a unit solely to provide a PPS?

* Is there a way to tell which revision/Option I have, eg.via inquiry
on the serial port?

My unit has no "Option" indication, all I have is FE-5680A / UN17491 /
serial nr. 27727W / Revision: B.
Without opening the unit at least, there are no other visible markings.

* J1-1 has function +15V, J1-2 is "+15V return", which, as I
understand it, means "ground" for the main power (I don't know how to
interpret "provides DC return" other than that).

However, there is also GROUND (J1-5), and there are at least the
following signals:

  - J1-3 Loop Lock Indicator (output; appears to be 5V, with 5V
meaning "no lock")
  - J1-6 Manual says "not used", but it carries a 1 us PPS (5V)
  - J1-8 RS-232 Rx (input for the FE-5680A)
  - J1-9 RS-232 Tx (output for the FE-5680A)

Should I assume that pins 3, 6, 8, 9 are all in reference to the
ground provided by pin 5?
Is pin 2 only "ground" for the pin 1?
Is there any relation between the voltage levels at pin #2 and pin #5?



Any help is greatly appreciated!

Sidney