On 2/4/2012 12:17 AM, John Miles wrote:
In the current 5680A units, the 10 MHz output comes from the 60 MHz VCXO
(divided by 6 in CPLD) and not direct from a DDS. If my architecture
understanding is right, the DDS signal output is mixed with the VCXO
output
only at the 114th harmonic of 60
From your comments, it sounds like you may be measuring one of the
earlier 5680A's that could be tuned over a large range with a DDS output.
These earlier ones had a 50.25 MHz internal osc which was locked after
multiplication to the rubidium frequency. Then there was a DDS on the
output
Hello, John,
Your phase noise plot seems quite similar to that sent by Said some time
ago (4 Jan), that looks like a lot of spurs quite evenly separated. It
is likely from the price and p/n that your unit is one of the newer
ones with 60MHz xtal and the DDS inside the loop - and I would think
Maybe his are new. But I bought one from ggg*fitting that was listed as new
turned out very used, and in conversation with them they had to admit they
do not know what they have. If it still has its original factory setting,
measuring the frequency will tell you if it had extensive running
From: John Miles jmi...@pop.net
So far, the FE-5680A is doing well in the ADEV department, but its AD9832
DDS chip adds some substantial noise and spurs to the 10 MHz output. [...]
The overall SSB C/N ratio I'm seeing between 1 Hz - 100 kHz is pretty much
in line with Analog Devices'
