[time-nuts] FE-5680A word of caution

[Jerry]

Just a word of caution to possible buyers of the Chinese Rubidium
FE-5680A boxes.
There has been a lot a discussion on the list lately about using the
popular FE-5680A as a portable frequency standard and I have being
working on using one of the cheap FE-5680A boxes myself.  I have found
that many of them do not output a useful 10 MHz signal.  The 10 MHz
output is not close to the expected frequency tolerance.  The first of
the units that I received puts out a signal at 9,999,945 Hz.  The
vendor then sent a second unit which puts out a signal at 10,000,025
Hz.  The vendor is in China and while he has been willing to work with
me by sending a second unit with me paying only postage, the time
delay in shipping from China and the cost of postage is prohibitive.
What concerns me the most is that the vendor says that both units were
tested before shipping.  In reviewing the Internet I found several
other reports of similar problems with FE-5680A units.  The units that
I have been working with are FEI FE-5680AFEI P/N 217400-30352-1.
These units all require a 5 volt input in addition to the 15 to 18 vdc
input and these units are not programmable via an RS-232 port.  These
units are being advertised by several vendors on E-bay.  I am sure
that there are good FEI units available but there is no way of telling
which are good and which are bad until you get the unit and check it
out and if it is bad you may just be stuck with it,  Only my
experience yours, may be different
Jerry