[time-nuts] Ultra High Stability Time Base Options for 53132A

Richard (Rick) Karlquist richard at karlquist.com
Sun Apr 12 19:48:37 EDT 2015



On 4/12/2015 2:22 PM, Magnus Danielson wrote:
> Hi,
>
> The buffer transistors has not AC-bypass of the emitter resistance, so
> that the DC current becomes large and thus contributes flicker noise.
>
> The comparator at the bottom isn't doing a beutifull work of squaring
> things up without contributing noise, considering the sine output of the
> 10811.
>
> Was that it, Rick?
>
> Cheers,
> Magnus
>

The resolution of page 13 is poor, and it seems to be a bitmap instead
of a vector file.  The fuzzy thing in the lower right corner looks
like it might be a comparator.  I think this was the smoking gun.

There was a saying by H.L. Menken to the effect that for every
complex problem, there is a simple, obvious, invalid solution.

Squaring up a 10811 with a comparator is a perfect example of this
principle.  Non-time-nuts always seem to gravitate to this design.

Of course you're right, any comparator will add jitter to a 10811.
The faster they are, the more jitter they add.

I noticed that the standard 10 MHz oscillator is built with
an ECL line receiver.  Another example of Menken's saying.
This is a TERRIBLE oscillator design, but one that would appeal
to the non-initiated.  I built one of these oscillators in 1976
at the suggestion of my boss.  After seeing how bad it was, I
quietly designed it out and never used it again.

Rick Karlquist N6RK



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