Subject: Re: AN: New Logic Analyzer, 500MHz, $166
Date: Mon, 18 Nov 2002 03:02:06 -0000
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NNTP-Posting-Date: Mon, 18 Nov 2002 03:09:15 +0000 (UTC)
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Jeff Liebermann wrote
> Anyway, my points are that:
> 1. 30 cm test leads are rediculously long.
> 2. Performance at 500MHz is not possible with 30 cm test leads.
> 3. Performance bandwidth and loading reactances should be specified
> with some sensible test leads included.
You are quite right, but this is how decisions get made:
1. you design and checkout a logic analyzer with somewhere
around 8mm (+pin length) from the input connector, via
the RC network, to the measuring IC.
2. you write it up, include instructions on making up a simple
test hookup, and send out to friends for evaluation. The
instructions also include "your friendly local distributor
may offer additional (i.e. expensive) probing solutions"
3. the feedback is that the testers do not want to make up
test leads, or to buy them separately from distributors.
"We want to get a simple hookup from you."
And you end up with a "standard hookup" which is really "the
cheapest possible hookup", connected to a darn fast analyzer.
Further muddying the "sensible test lead" water, there are many
folk out there who want something which will spend most of its
life looking at relatively slow signals, but which could be wired
for speed (with short leads) when required.
FWIW, my personal analyzer has the leads shortened to 5cm, but
I don't suppose that would appeal to the typical user. My HP
analyzer has approximately 28cm from the clip to the pod.