[time-nuts] FTS-4060M/S24

christopher hoover ch at murgatroid.com
Thu Jun 19 23:33:50 EDT 2008

Mark Sims wrote:
> I recently bought a FTS-4060M/S24 cesium beam unit.  It is a rather
> stripped down model,  with 1MHz on the front panel and only
> 1/5/10MHz/Fault BNC's on the back (does not even have the monitor port
> on the back).

My experience is with a 4050/S24.  After some work, mine is pretty much a
standard 4050.

The /S24 option for the 4050 and 4060 is an indication of a US government
model.  The /S24 specs are looser than FTS 4050/4060 standard specs, so it
is possible that FTS sorted tubes accordingly.  I don't know this to be
true, but I can say that my 4050/S24 tube is not as good as my 5061b that
has a Datum equivalent tube in it.

Other than that, at least for the 4050, FTS didn't really do much to
"downgrade" the unit -- some connections never make it from the CBT module
to the front and back and a few divider board changes were made to provide
different outputs.

It is easy to add the appropriate plumbing from the CBT module to bulkhead
connectors and/or switches to get those capabilities back.  I don't recall
exactly, but I think it was 1PPS out, 1PPS SYNC in, 10 MHz rear out, and the
sync button.

The one board I had to "fix" divided the CBT module reference down to 1 MHz
for (IIRC) the front panel.  It was the standard board, but it had been
re-worked to meet government specs.  It was fairly easy (aside from the
conformal coating) to undo the re-work and return it to its original


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