[time-nuts] Re: Phase noise of HP8663A 640 MHz reference?

[Pluess, Tobias]

Hi Ed,

could you share some info about your own 640 MHz source?
I would be very interested.
I do have an 8663A, but I have no idea about how good it actually is and
currently, I don't have a possibility to test it because I still lack an
11729C carrier noise test set (but I would like to make something similar
myself some day). Apparently my 8663A is one of the latest units, because
it is already labelled Agilent.

best
Tobias


On Sun, Aug 14, 2022 at 8:11 PM ed breya via time-nuts <
time-nuts at lists.febo.com> wrote:

> Thanks all, for replies and possibly running some tests. The reason I'm
> asking about this is that now that I finally have the HP8663A, I'd like
> to rig it up with the HP11179C, and its documentation mentions all this
> option 3 stuff on the 8663A. So I started wondering, just how good is
> it, and if there's a "typical" or representative spec. Again, I believe
> option 3 just means that the particular unit was tested at the factory
> before delivery, and the results documented and included with the unit.
> Over time, this info could be lost.
>
> My unit has option 2 only, which is fancier phase modulation, that could
> be handy for some things. Before it arrived, I studied up the design and
> evolution in the manuals. It appears that the 8662A and earlier 8663A
> models may have had the 10544 OCXO installed, while mine is one of the
> later versions, officially sporting the 10811-60111. I found that this
> is indeed what's in there, and the cal seal is marked ca 2014 - likely
> the last time it was messed with. It seems to work so far, and it is
> quite an impressive beast.
>
> On the 11179C, I had a stroll down memory lane for a while. I kind of
> forgot how much I had worked on it about a dozen years ago. Since I had
> no prospect of getting a 8662A or 8663A back then, I had been collecting
> and mounting parts to make a fairly high grade built-in 640 MHz source.
> The scheme was based on a 80 MHz VTOCXO, to be doubled up and filtered
> thrice to 640 MHz, and phase locked to 10 MHz if needed. I already had
> all the major pieces fitted, and a bunch of notes on the design details.
>
> I started yanking all this stuff out to restore it to stock, but then
> started thinking "not so fast - maybe this could be pretty good after
> all." Since I really don't know how good the 640 MHz from the 8663A is,
> I'll keep all the pieces and info from the other scheme together, just
> in case.
>
> Ed
>
>
>
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