[time-nuts] Using the LT3042

[Anders Wallin]

FWIW for the 10MHz distribution amplifier I have been using LT1963 (40
uVrms in 10Hz to 100kHz) which is about 40x worse than the LT3042 spec of
0.8 uVrms in 10Hz to 100kHz.
With decent op-amps I think the distribution-amp performance is limited by
the op-amp noise and thermal noise in the resistors - I wouldn't expect the
residual phase/amplitude noise to improve at all with a better LDO like the
LT3042 - but ofcourse I haven't tried this :)

The LT3042 spot noise spec of 2nV/sqrt(Hz) corresponds to Johnson noise of
a 250 Ohm resistor at room-temperature (if my spreadsheet-calc is right..)
- so I guess if one has circuits that are already optimized/limited by
supply voltage noise at that level then moving to the LT3042 makes sense.

AW

On Wed, Jul 10, 2019 at 12:02 PM Perry Sandeen via time-nuts <
time-nuts at lists.febo.com> wrote:

> Yo Bubba Dudes!,
> The LT3042 seems to be a wonderful part.  But having learned a long time
> ago the it wasn't wise to gold plate a Yugo, so when are there diminishing
> returns?
> For example I have several HP 10811 oscillators. one is in a HP5335a
> counter that I'd like to make as stable as reasonably possible. Another
> HP10811 needs a power supply.   Also several Lucent XO OCXO's.
> So where is it practical to hack for better results and when do you use
> some not -as -wonderful regulator chips that come in a much easier to use
> dip package for a power supply upgrade?
> Regards,
> Perrier
>
>
>
>
>
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