[sdiy] WTB: Paia EKx40

[Magnus Danielson]

From: "john mahoney" <jmahoney at gate.net>
Subject: Re: [sdiy] WTB: Paia EKx40
Date: Tue, 9 Mar 2004 19:42:10 -0500
Message-ID: <032f01c40638$85c17580$6400a8c0 at BABYUTEST>

> > ----- Original Message -----
> > From: "Harry Bissell Jr" <harrybissell at prodigy.net>
> > |
> > | IMHO a sine wave has NO harmonics, a VCO has no drift
> > | or jitter, sawtooth and pulse waves have infinite
> > | (fast) rise (and or fall) times.
> >
> > That is not opinion, humble or not. That is the definition ;-)
> 
> Well, we need infinite rise times and *linear* fall times on the sawtooth
> waves.
> --
> john  <--(being extremely picky, and hoping that linear is the right term)

Linear in what respect? :->

You mean to say that there is a constant (positive) slope between the
infinit fall-times.

BUT! Being picky like hell... you will *NEVER* have that, since even if you
have say 50 GHz of bandwidth, you have a fall-time of about 7,5 ns. For 40 GHz
you would be patching with semirigid cable and SMA connectors.

So... "infinit fall and rise-times" is just down the trash before you got up.

... and jitter/wander free? BHA! Phase-noise of various sorts is a matter of
life, or maybe you have borrowed my mystery magical -35 K cooler-spray? ;O)

In state of the art research atomic clocks they laser-cool their atoms down to
a few uK in order to lower the temperatur based phase-noise (doppler/relative
effects included!).

So, being picky means realizing just which deficiencies we must learn to live
with, the issue is really how grave they are. What we needs to learn is when
lowering stuff under some limit means there is nothing more to do. Thus, how
much nearer the "ideal" it is meaningfull to go. We can't do much better than
such rough engineering rule of thumbs it seems.

Cheers,
Magnus