[time-nuts] Re: Thunderbolts

[Dana Whitlow]

Bert, remember that I need a very long locking loop time constant setting in
order to smooth out GPS noise, so in a sense the GPSDo is *almost* in a
holdover state anyway, all the time.

Probably the smartest thing for me to do is to buy a spanking new PRS-10,
with the PPS locking feature present.  Then I could just leave it locked to
GPS most all the time, but disconnect the PPS and let it go into holdover
on the rare occasions when I need a few hours of even better stability.

Dana


On Tue, Jul 20, 2021 at 6:56 PM ew via time-nuts <time-nuts at lists.febo.com>
wrote:

> There is a lot of misinformation out there. It is not the OCXO that
> changes, Bruce did extensive testing and I did some too. The Vectron is
> super, would like to know what is in it but do not want to open one. Once
> warmed up the stable OCXO temperature is a main contributor to the board
> temperature. Using a Dual Oven may give you a warm feeling but only adds 1
> more Watt of stable heat to the board making the temperature change
> smaller. The OCXO is important during Hold Over and that is why it is
> there. The changes are the DAC which is updated once a second. Very
> temperature sensitive. Cheap. We have done the tests   10811, OSA 8600, FRK
> and M100. For fun did use a cheap small OCXO, no performance change. Was
> done in Juerg's temperature stable basement.  See attached picture.
>
>                                             Bert Kehren
> My experiences with the T'Bolt have not been entirely satisfactory.  If I
> set the loop
> lime constant long enough to get a satisfying smoothing of the GPS noise (a
> few hundred
> seconds), then the thermal sensitivity of the VCXO on the T'Bolt rears its
> ugly head and
> I see a lot of my HVAC system cycling instead.  The T'Bolt E supposedly has
> a double-
> oven XO, so I'd like to give that a try.  But my wallet says "whoa"!
>
> According to Bodnar, his units do have some choices in the time constant
> setting.
> I've been considering ordering a Bodnar just for frequency agility, but
> have been
> holding off out of concern for the complications of dealing with a foreign
> supplier.
>
> Dana
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