[time-nuts] trimble Thunderbolt, how to get 25 or 27 mHz from it??
marklgoldberg at gmail.com
Sat Jan 20 13:22:33 EST 2018
I am using Leo Bodnar's GPSDO that is based on the 5328 and what looks to
be a good TCXO as an external reference clock for a Perseus SDR. Using
that, I measured phase noise and Allan Deviation of the best sources I have
available and found the phase noise and Allan Deviation to be close to what
has been measured on more expensive equipment. From a quick look at the
5351's data sheet it's jitter appears to be on the order of 100 times more
than the 5328, and would result in unacceptable phase noise for my
I would expect that the 5328 with the Thunderbolt as an input source would
be even better than Leo's GPSDO. Note that the two outputs from the 5328
can't be two arbitrary frequencies, and I have found that different values
of the various dividers can produce the same output frequency by varying
levels of close in spurs.
See my sites listed below for all the details:
On Sat, Jan 20, 2018 at 6:59 AM, John Ackermann N8UR <jra at febo.com> wrote:
> Hi Mark --
> Thanks! To clarify, when you say you've found "it" acceptable, you're
> referring to the 5328?
> What caught my eye about the 5351 was the three (or eight) outputs. My
> idea was to build a board that would provide independent LO oscillators for
> multiple VHF/UHF transverters. It looks like the 5328 has two outputs,
> which is still useful but would require putting two or three of them on the
> board. Which isn't the end of the world.
> On 1/19/2018 8:56 AM, Mark Goldberg wrote:
>> On Jan 19, 2018 6:01 AM, "John Ackermann N8UR" <jra at febo.com> wrote:
>> Sorry to hijack the thread, but the Si5351 looks interesting for another
>>> project I'm working on. I know it specifies "low jitter" but has anyone
>>> looked at the phase noise? Is it usable for RF applications?
>> Datasheet states jitter in the 40-70 ps range. That is not very good. If
>> you want something suitable for RF applications, look at the Si5328. It
>> jitter on the order of 300fs.
>> I believe Leo Bodnar uses it in his GPSDOs and I can confirm the phase
>> noise and Allan Deviation others have found and it is suitable for me for
>> RF applications. It is not nearly as good as the Thunderbolt though. It
>> will generate almost any frequency you want.
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