[fa.telecom] TELECOM Digest V4 #187

telecom@ucbvax.ARPA (05/04/85)

From: Jon Solomon (the Moderator) <Telecom-Request@BBNCCA>


TELECOM Digest     Fri, 3 May 85 23:36:26 EDT    Volume 4 : Issue 187

Today's Topics:
                       Racal-Vadic Modem Query
                      Re: TELECOM Digest V4 #186
                      Telephone wiring diagram?
                      Re: TELECOM Digest V4 #185
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To: TELECOM@bbncca.ARPA
Subject: Racal-Vadic Modem Query
Date: 01 May 85 23:11:58 PDT (Wed)
From: larus%ucbdali@Berkeley

I have a Racal-Vadic VA3451 Auto Dial Modem at home.  When I dial into
Berkeley's computers, about half the time I get a "CONNECTED" message
and then nothing.  No manner of key pounding will get me a login
prompt.  However, hanging up and trying again usually works.  I am
begining to suspect that there is some sort of of incompatability
between R-V's triple protocol and the 201/212 modems on the computers.
Has anyone else seen this problem and know of a solution.

Thanks,
/Jim

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From: ihnp4!ihopa!riccb!jmc@Berkeley
Date: 2 May 85 04:43:21 CDT (Thu)
To: ihopa!ihnp4!ucbvax!telecom@Berkeley
Subject: Re: TELECOM Digest V4 #186

Regarding surge protecters for telephone lines.

Surge protectors, as the name implies, protect the equipment and user
on a telephone line from large voltage transients.  Normal telephone
equipment is transformer coupled to the line and if they meet REA spec's
should be able to handle 1000 V transients without burning.  To limit
lightening strikes Bell puts arrestors on the office end which limit 
transients to about 400 V.  I believe arrestors are also used on the
customer premises but I'm not sure what the limits are.  $19 seems
outrageous since these things are nothing but gas discharge tubes.  I've
seen them go down to 90 V, anything below that will start firing on 
ringing voltage.  REA standards say the equipment won't burn after so
many consecutive 1000 V strikes but does not imply that it must work
afterwards.

                                  Jeff McQuinn * Rockwell International




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Date: Wed 1 May 85 20:01:31-PDT
From: Doug <Faunt%hplabs.csnet@csnet-relay.arpa>
Subject: Telephone wiring diagram?
To: telecom@bbncca.ARPA

I have a old Trimline telephone that I'd like to get
wired correctly.  It is a '69 vintage unit that requires
a transformer for lighting the buttons.
I've managed to get the switch-hook wiring sort-of figured out,
but can't seem to get the bell to work properly.
The bell has five wires coming out of the bell, colored:
Red, Black, Blue, Slate, Slate/Red
The terminal plate has a capacitor between terminals K and A.
The rest of the terminals are marked L1, L2, 1, 3, 4, B, F, G, and C
The handset has 5 leads: Red and Green are Tip and Ring, Black and
White are the lighting circuit, and Yellow is ?

Does anyone have a wiring diagram?

		faunt%hplabs@CSNET-RELAY.ARPA
-------


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Date: Wed, 1-May-85 22:20:26 PDT
From: vortex!dave@rand-unix (David H. Siegel)
Subject: Re: TELECOM Digest V4 #185
To: randvax!telecom-request@bbncca
Cc: vortex!i@rand-unix

	Lightning is a wonderful display of nature.  It is so wonderful
that you do not have to be anywhere near it to lose eyour electronic
toys.  1.  Underground telco cables are not immune to hits.  Surges are
induced very well in burried cabl.  2.  Protectors only divert 
"excess" voltages to ground... when they get around to it.  The idea is
to keep the amount of energy to the inside telset as low as possible.
3.  MOV's can only handle their rated power dissipations before they self-
distruct.  In sensibly designed equipment they are only used as secondary
protection.  (The protectors are the primary line of defense).  4.  The 
best protection is obtained with a combination of devices:  Gas tube 
protectors, premises equipment with good secondary protection to a good
earth ground and well grounded chassis.  For power a 3 mode surge arrester
is a good start (well grounded please).  For CATV drops grounding blocks
are a must.  A cheap 50 cent balun transformer on the back of your TV 
can't hurt either.  5.  No kite flying during thunderstorms, or your
Telcom Digest will be cancelled.

					Dave Siegel


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End of TELECOM Digest
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