The midnight oil that would have been spared if you used sinewave would have
been spent on debugging problem coming from jitter of sinewave clock, so I
do not think that you have anything to regret.
As for coax cable, unless you used a ? inch rope (RG6) or foamed dielectric
(what was very expensive 10 years ago), your standard ? inch cable would
have been around 30 pF/ft, 5 pF give or take, so you were dealing with 450
pF load. A driver that comes to mind is National's DS0026, which is
characterized for 500 and 1000 pF load (I had to actually go and check for
what loads is driver characterized), but that is a driver that was not
widely known or used, so its availability might have been poor.
Regards
Miroslav Pokorni
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-----Original Message-----
From: F F [mailto:ferfons@...]
Sent: Wednesday, July 11, 2001 1:42 AM
To: TekScopes@...
Subject: Re: [TekScopes] Coax BNC Cable Termination
Re John's comments, I agree and I'm pretty sure a sinewave
would had spared
me the midnight oil ;-)
Re Miroslav comments, I can't remember the cable's cap spec
- this took
place some ten odd years). What I can tell you though is in
fact it wasn't
easy to pick a suitable driver for this application.
Fernando
Portsmouth, UK
>From: "John Miles" <jmiles@...>
(snip...)
Also keep in mind that a 1 MHz square wave needs at least 10
MHz of
error-free bandwidth, preferably more, to come out looking
right. With a
sine wave, you might never have noticed the problem.
>From: Miroslav Pokorni <mpokorni@...>
(snip...)
>The 5 meters of cable is still 450 pF, still quite load for
most drivers.
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