[comp.sys.ibm.pc.rt] RT cable lenghtquery

lind@utc.chalmers.se. (Borje Lind) (03/16/89)

Someone asked if the RT monitor cable could be extended as the one for the
SUN (where you for example just take ordinary tranciever kable and 2 dsubs's
and make the cable as long as you like - we've made 15 meter (45 feet) cables
whitout any trouble). I don't know anything about the Moniterm screen, but
if you're using the horrible 6155 you're in trouble. The adapter card has
TTL-levels as output and the cable consists simply of 8 twisted pairs.
The cable also has 3 ferrites attached to keep emissionlevels down and
lower the inpact of bouncing signals. This cable CAN NOT simply be extended.

An hardware expert at computer society here at Chalmers has solved the
problem by converting the signals coming out from the adapter to ECL,
run it through an extension cable (15 meters without problems) and then
converted the signals back to the original TTL-levels again. It's a bit
more complicated than for the SUN, but it works. The trouble is to get
hold of the AMP connectors here in Europe. The keyboard and mouse cables
could easily be extended with a good quality, shielded twisted pair cable.
(Cut the cable and put in D-subs and extension cable. The original 
connectors are HARD to get hold of. WHY CAN'T ANYONE TEACH IBM TO USE
STANDARD DSUBS?)

If you need furter info on the ECL-conversion, send a mail to our
hardeware expert: radar@cd.chalmers.se. I'm sure he won't mind.

		Borje

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*	Borje G. Lind							 *
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