Am 22.10.20 um 23:54 schrieb Richard (Rick) Karlquist:
I suspect that the stock 5065 chain has better
phase noise than this chip. I know for sure
that you can get much better phase noise than
this chip by using conventional architectures.
Of course they are more complicated, etc. Just
wanted to put this chip in perspective.
Rick N6RK
On 10/22/2020 12:12 PM, Gerhard Hoffmann wrote:
This is a ADF5356 with 2 LT3042 to clean up the supply voltage.
I measured the successor to this board yesterday on 10 GHz out
with my new 1/8 prescaler and the SR620 counter and some
As long as you can measure the noise with a 89441A vector signal
analyzer instead of a signal source analyzer, it cannot be leading edge.
Close-in, it seems quite ok. Enough to guide a 5 MHz crystal oscillator,
and
also to guide a (in my case) 10 GHz dielectric osc with a Q of 20 to 30K.
Sorry, I must stay diffuse at this point.
My question for the phase noise in the Engineer Zone was also kinda
"scheinheilig",
German word, (hypocritical, falsely innocent, ...lost in translation). I
know that I could
go to a phase detector frequency of 150 MHz with this chip (instead of
20*2), and it
would help for sure. But I'm still struggling to make a connection between
the Windows evaluation software results and the data sheet. My software
driver is
1200 lines of C code (but including lots of comments.) ~400 bits to be
set up.
And the 100th harmonic of 60 MHz won't be a phase noise wonder either, with
or without a SRD. You can see the effect in the well-known pictures of
the old
HP spectrum analyzers that display a staircase with many a step,
depending on
the LO harmonic.
Sky and MA/COM still make step recovery diodes, whether they fit is a
different
question. But I cannot think of a special SRD failure mode. If you can
do that,
solder it out and measure it with a normal Ohm meter. If it still
behaves diode-ish,
it is very probably a working SRD. Maybe without the soldering,
depending on the circuit.
Repairing will always be cheaper than transplanting a completely new heart.
Cheers, Gerhard
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