[time-nuts] FE-5650A

Murray Greenman murray at rakon.co.nz
Mon Apr 28 14:35:26 EDT 2008


I have an FE-5650A, and am very pleased with it. Yes, it will operate on
any frequency from 0 to nearly 20MHz, but I think it will depend on
which option you get. Mine was an Opt 58 I think, which originally had
outputs at 8.388688MHz and 1pps. It is now modified to add a serial link
for control and a low level output (bypassing the peaked output
amplifier/filter). If you buy one the same, I would be happy to send you
my control software, although in truth it is easy to control with a
terminal program or to write your own software.

The price you quoted sounds very good, and is cheaper than a GPSDO,
unless you can find a used one from a Telco. I have several used ones,
and the price in all cases was lower than the FE-5650A. If you want a
new GPSDO, look at the Jackson Fury, as it is relatively inexpensive
(but still at least twice the price you quoted for the FE-5650A).

I would not recommend changing the DDS chip (which is an AD9832) for
anything better. It would be a huge effort and the chances of success
not good, and besides, the micro in there is intended to drive the
AD9832. The AD9832 performs very well, and with a ~50MHz clock gives
about 10mHz resolution. I don't have any trouble with spurious outputs,
and the phase noise is quite good -145dBC at 1kHz, -125dBc at 100Hz. Not
stunning, but still very useful.

Yes, the unit does run quite hot. There is one face which is intended to
be connected to a heat conducting surface. I am running mine with no
heatsink, but do not usually run it for very long. I plan to rebuild
including a small heat radiator and maybe a small computer fan.

Murray ZL1BPU

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