Am 12.11.2016 um 23:52 schrieb Bob Camp:
Hi
Yes, the FE-405 uses a DDS and a cleanup. Inside the cleanup loop the DDS spurs
come
straight through. Since the FE-405 compensates for all sorts of things, the DDS
moves
around a lot. Even a one bit change on a DDS will move spurs around. With an
ever changing
DDS, you have an ever changing forest of “stuff” on the output.
I would not expect a lot of dynamics after a month of cont. power up.
And the spurs
do not move and they don't average away, at least not within my limits
of boredom.
The PLL bandwidth seems to be 50 Hz, so the forest from 100KHz to 5MHz is
far out. That seems somewhat weird and raised doubt together
with the power level being out of spec.
Not the best thing for a “standard” …..
I've tried to kill 2 birds with one stone. The FE405 had collected dust for
months and still was mostly untested.
The oscillator is not part of the "standard"; I could have used a BVA or
a maser by just plugging in. I just needed a centre frequency with a
few dBm for the E5052B to lock on.
All I want is some known phase noise reference reference lines
for my private phase detector experiments. Recalibating the
phase detector by modulating oscillators on different frequencies
is no fun if you change the Schottkies every 2 minutes.
regards, Gerhard
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