Re: [time-nuts] ACAM GP22 Chip

[Thomas Allgeier]

Hello Hal,

The book has been sourced and is on its way to me - a good pointer, thanks. 
With it and the comments I have had from you guys I expect I will get pretty 
much what I want, given a little time which thankfully I have.

I will report back any outcome that looks plausible / presentable.

Kind regards,
Thomas.
----- Original Message ----- 
From: "Hal Murray" <hmur...@megapathdsl.net>
To: "Discussion of precise time and frequency measurement" 
<time-nuts@febo.com>
Cc: <hmur...@megapathdsl.net>
Sent: Tuesday, November 24, 2015 7:44 PM
Subject: Re: [time-nuts] ACAM GP22 Chip



th.allge...@gmail.com said:
I should say from the start that I am new to time and frequency 
measurements
and not even an electronics engineer – but then I have been exposed to
high-precision electronics for the last 25 years hence have picked up 
some
dangerous degree of half-knowledge.

Do you have a copy of Art of Electronics by Horowitz and Hill?


In order to evaluate the chip I was planning to replicate John A’s
experiment with the coaxial delay line from the HP5370b – but as my 
interest
is in “measuring range 2” of the GP22 I need a delay of 500 ns or 
more
(actually 1 µs sounds a better start). This is the equivalent of a 200 m
length of cable. I fear trouble with this: Am I not getting unwanted
inductivities if I use a coil of that size?

The trick is that your coil has 2 wires.  It's a transmission line.

Here is the handwaving explanation: The current on the return path is 
going
in the other direction and cancels out the inductance.

Twisted pair will work almost as well as coax, maybe better than cheap 
coax.

AoE has an appendix on transmission lines.  You can find lots of info on 
the
web.  You need to terminate it.  You will want a scope to check the
termination.



--
These are my opinions.  I hate spam.



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