[time-nuts] Noise and non-linear behaviour of ferrite transformers

Attila Kinali attila at kinali.ch
Sun Jul 20 05:04:22 EDT 2014

Good morning!

On Sat, 19 Jul 2014 18:38:17 -0700
"Richard (Rick) Karlquist" <richard at karlquist.com> wrote:

> I did some tests of residual phase noise using an
> Agilent E5505A and found that air coil inductors
> did not add noise (at least down to my noise threshold)
> but that ferrite core inductors had easily seen noise.
> It was on the order of ADEV = 1E-10 close to the
> carrier.  I would describe this as noise rather
> than non-linearity.

Interesting. Do you still have that data? It woud be
very interesting to have a look at it.

> In my case, the inductors were used to make tuned
> circuits.  This is different than your case where
> the ferrite is being used to make a transformer.
> So as they say "your milage may vary".  And you
> probably don't have the option of an air core.

I also pondered using air core transformers, but
i fear that the noise pickup of those is much worse
than what the ferrite would do.

> After obtaining the E5505A and using it for a while,
> it became clear that anyone who is serious about
> component noise has to measure the components of
> interest to them in the application of interest
> to them on the E5505A or equivalent.  (And the
> Agilent E5202A Signal Source Analyzer isn't
> equivalent.)  Unfortunately, the E5505A is quite
> expensive and requires a highly skilled user.

A E5505 is slightly out of my budget. 
Is there any similar system that could perform
on a similar level, but is slightly cheaper?
I dont need 26GHz of bandwidth after all.

> You mentioned "theory" several times.  This sort
> of thing is 1% theory and 99% experiment.  Or
> another way of putting it is you do a bunch of
> measurements and then construct a theory to
> explain what you already know experimentally.

Well, yes. The catch here is, that i dont have
the equipment to measure on that level. And i would
like to understand what i am dealing with.
Constructing a theory out of experimental data
works only if you can trust the data. And even
then it's a damn lot of work to have something
consistent and half way general.

			Attila Kinali

I pity people who can't find laughter or at least some bit of amusement in
the little doings of the day. I believe I could find something ridiculous
even in the saddest moment, if necessary. It has nothing to do with being
superficial. It's a matter of joy in life.
			-- Sophie Scholl

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