27 Jul
2006
27 Jul
'06
7:42 a.m.
Hi,
Several of my older machines run on 10Base2 networks, here.
I have found that traditional BNC tee's make cable dressing
problematic. But, "goal post shaped" tee's seem to be kinder
to the cables. (I haven't yet tried "F"-shaped tee's but I
suspect they wouldn't be as good as the goal posts).
Problem is, I don't find these sold many places. Seems
like regular tee's are the norm.
Pointers?
Thanks!
--don
27 Jul
27 Jul
1:57 p.m.
New subject: 10Base-2 : Terminating resistor rating?
Hi all,
What is the resistance of a 10Base-2 terminating resistor?
Joe
2:02 p.m.
New subject: 10Base-2 : Terminating resistor rating?
On Thu, 27 Jul 2006, Joseph Stevenson wrote:
What is the resistance of a 10Base-2 terminating
resistor?
50 ohms.
Mike Loewen mloewen at cpumagic.scol.pa.us
Old Technology http://ripsaw.cac.psu.edu/~mloewen/Oldtech/
6:53 p.m.
New subject: 10Base-2 : Terminating resistor rating?
On Thu, 27 Jul 2006, Joseph Stevenson wrote:
52 ohms was also used. I think maybe 50 ohms is a non-standard value for
a
resistor, and 52 ohms was available. I only saw one batch of 52 ohms-- the
color stripes said 52 ohms, not just my ohmmeter.
What is the resistance of a 10Base-2 terminating
resistor?
50 ohms. 
11:51 p.m.
New subject: 10Base-2 : Terminating resistor rating?
Tom Peters wrote:
52 OHMS is within 5% of the correct value. If they were 5% resisters,
they would easily be within 10% of 50 ohms. They are probably close
enough to do their job.
This table
50 ohms * 1.10 = 55 ohms for the high +10%
52 ohms * 1.05 = 54.6 ohms for the high +5%
52 ohms * .95 = 49.4 ohms for the low -5%
50 ohms * 0.9 = 45 ohms for the low -10%
shows that a 52 ohm +/-5% is easily within the range of a
+/-10% 50 ohm resister.
On Thu, 27 Jul
2006, Joseph Stevenson wrote:
52 ohms was also used. I think maybe 50 ohms is a non-standard value for a
resistor, and 52 ohms was available. I only saw one batch of 52 ohms-- the
color stripes said 52 ohms, not just my ohmmeter.
What is the resistance of a 10Base-2 terminating
resistor?
50 ohms.
29 Jul
29 Jul
1 a.m.
New subject: 10Base-2 : Terminating resistor rating?
On Thursday 27 July 2006 02:53 pm, Tom Peters wrote:
First I've heard of that one being a standard value, but my perception of
those is a little skewed anyways, since when I started messing with this
stuff 20% parts were still common.
In the whatever-the-heck series it is that gives you 5% values 51 ohms is in
there.
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
On Thu, 27 Jul
2006, Joseph Stevenson wrote:
52 ohms was also used. I think maybe 50 ohms is a non-standard value for a
resistor, and 52 ohms was available. I only saw one batch of 52 ohms-- the
color stripes said 52 ohms, not just my ohmmeter. What is the resistance of a 10Base-2 terminating
resistor?
50 ohms. 
27 Jul
27 Jul
2:03 p.m.
New subject: 10Base-2 : Terminating resistor rating?
50-ohm I believe.
----- Original Message -----
From: "Joseph Stevenson" <ikvsabre at comcast.net>
To: "General Discussion: On-Topic Posts Only" <cctech at classiccmp.org>
Sent: Thursday, July 27, 2006 8:57 AM
Subject: 10Base-2 : Terminating resistor rating?
Hi all,
What is the resistance of a 10Base-2 terminating resistor?
Joe
28 Jul
28 Jul
10:09 p.m.
New subject: 10Base-2 : Terminating resistor rating?
Hi all,
What is the resistance of a 10Base-2 terminating resistor?
Officially 50 Ohms, but that's not a prefered value. 51 Ohms is, and
works fine. I am pretty sure 47 Ohms would be OK too.
Note that the resistors serve 2 purposes -- they terminate the cable (to
remove reflections) and that act as a load for the transmitters, which
are actually current sources. The fact that 2 transmitters transmitting
at the same time will produce double the voltage on the cable is used to
detect colisions, so the resistor value has to be somewhat near right.
Don't fall into the trap of 'Oh, it's a short cable, reflections aren't
a problem, I can use anything'. The collision dections stuff will moan at
you :-)
-tony
11:49 p.m.
New subject: 10Base-2 : Terminating resistor rating?
On 7/28/2006 at 11:09 PM ard at p850ug1.demon.co.uk wrote:
Don't fall into the trap of 'Oh, it's a
short cable, reflections aren't
a problem, I can use anything'. The collision dections stuff will moan at
you :-)
If the network works at all. Mine won't work without terminators, period.
I still have a couple of old 10base2/T 6 port hubs that are coupled with
coax--everything else is 10BaseT cat 5.
At one time, I picked up a load of 75 ohm male BNC connectors (the screw-on
type) for next to nothing at a "going out of business" sale. Since I was
using 50 ohm coax, I wasn't able to use them without some pretty severe
modification*, so I stuck a 47 ohm resistor inside of each--they worked
just fine as terminators.
* the severe modification turned out slipping the 50 ohm coax into and
soldering it to a small length of thinwall copper tubing, which was then
the right size for the connector.
Cheers,
Chuck
29 Jul
29 Jul
12:52 a.m.
New subject: 10Base-2 : Terminating resistor rating?
On 7/29/06, Chuck Guzis <cclist at sydex.com> wrote:
On 7/28/2006 at 11:09 PM ard at p850ug1.demon.co.uk
wrote:
I found that out at a demo at a computer club meeting - I _had_
terminators, but they were uber-cheap... the resistor connection to
ground was the lead folded over and a plastic cap pressing it to the
side of the connector body. After a bit of time, handling, oxidation,
etc., it wasn't an effective connection. Sure worked well after
soldering, though.
-ethan
Don't fall into the trap of 'Oh, it's
a short cable, reflections aren't
a problem, I can use anything'. The collision dections stuff will moan at
you :-)
If the network works at all. Mine won't work without terminators, period.
8:48 p.m.
New subject: 10Base-2 : Terminating resistor rating?
On 7/28/2006 at 11:09 PM ard at p850ug1.demon.co.uk wrote:
Of course it won't work if it detects collisions all the time (if the
resistor is too high -- say just a terminator at one end of the cable,
then any transmission will look like a collision). But it can help to
know why it's not working.
-tony
Don't fall into the trap of 'Oh, it's
a short cable, reflections aren't
a problem, I can use anything'. The collision dections stuff will moan at
you :-)
If the network works at all. Mine won't work without terminators, period.
27 Jul
27 Jul
3:56 p.m.
On 7/27/2006 at 12:42 AM Don Y wrote:
Problem is, I don't find these sold many places.
Seems
like regular tee's are the norm.
Jameco stock 100597CK, page 145 in catalogue 262. $5.99 the each. They
also offer BNC tees in the "F" shape and the "90 degree T shape".
I haven't checked the usual surplus sources yet.
Cheers,
Chuck
4:27 p.m.
Chuck Guzis wrote:
On 7/27/2006 at 12:42 AM Don Y wrote:
Thanks!
--don
Problem is, I don't find these sold many
places. Seems
like regular tee's are the norm.
Jameco stock 100597CK, page 145 in catalogue 262. $5.99 the each. They
also offer BNC tees in the "F" shape and the "90 degree T shape".
I haven't checked the usual surplus sources yet.
6730
days inactive
6732
days old
14 comments
11 participants
participants (11)
-
ard＠p850ug1.demon.co.uk -
cclist＠sydex.com -
dgy＠DakotaCom.Net -
ethan.dicks＠gmail.com -
ikvsabre＠comcast.net -
jwest＠classiccmp.org -
kth＠srv.net -
mloewen＠cpumagic.scol.pa.us -
ploopster＠gmail.com -
rtellason＠verizon.net -
tpeters＠mixcom.com