[time-nuts] HP 3586 entirely referenced to 10MHz: A solution II

Chuck Harris cfharris at erols.com
Sat Apr 2 20:13:55 UTC 2011


Perry,

The bad part of your "solution", that you seem to be missing is the
BFO will not be locked or referenced to any standard but itself.  If
that is acceptable to you, then there is no need to reference your 3586
to anything but itself.... rendering the entire subject void to you.

The DDS solution makes the BFO frequency, which is very important in using
audio solutions to frequency measurement with 3586 referenced to the same
standard as the rest of the unit.  The small offset (not error) is easily
removed by simply subtracting, or adding it when figuring the result.  It
is constant, and will never change.

Unlike simply stabilizing the BFO crystal as you propose.

-Chuck Harris

Perry Sandeen wrote:
> List,
>
> Wrote: Your simple idea is a non-workable concept.
>
> Now how do you actually know that?  It’s an opinion that would have to be proved
> or disproved by actually doing it.  I based my opinion on the graph that showed
> the HP crystal frequency change verses temperature which was IIRC, quite small.
>
> Wrote: Instead of whining about the complexity<snip>
>
> Well, I’m sorry if a different viewpoint, in the way I expressed mine, causes you
> to give me a personal derogatory label instead of the usual gracious responses
> others on the list have provided me.
>
> Wrote: why not contact Bert or Paul Swed and see if one of them would do you a
> favor and build the item for you.
>
> Well that never occurred to me.  If that thought had occurred to me, I wouldn’t
> have pursued it for two reasons.
>
> 1.  It almost works.  It it is a great improvement over the stock HP crystal
> oscillator but it still has some small errors do to the DDS scheme.
>
> 2. I have five working 3586B units and as I understand the article, I might need
> to have five different programs as each unit may have different nuances.  And as I
> noted in my post, I have no programming ability or any source to one.  And I also
> said in my post that if one can do it to go for it.
>
> Wrote: I do not believe the hookup part is that hard to do and if you follow
> instructions well it should be quite doable.
>
> I completely agree.  I’ve worked on the innards of mine changing out a WECO
> connector for a BNC.  The 3586 at 58 pounds it is heavy as heck because of all of
> its shielding but is surprisingly modular and easy to open and dis-assemble.  (One
> should seriously consider replacing the power supply electrolytics is one is going
> to open the beast up.)
>
> For the present I plan on using the measurement technique that Burt Weiner K6OQK
> so graciously shared on the net and to us on the list.  Locking my 3586 and 3336
> to my GPSDO should allow me to get good results.  I also can compare my first
> GPSDO to a second redundant GPDSO.  This I can understand and do.
>
> Regards,
>
> Perrier
>
>
>
>
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