I have what I think is an unsual question which I couldn't find an
answer to: in my attic there is a coax splitter with several coax
outputs to coax cables which snake into the ceiling and disappear in
the boweles of the house. They are all of the same color and have no
identifying marks. In the house itself, there are coax jacks in
several rooms.

And now the question: is there a way to determine, without buying
expensive equipment, which cable in the attic leads to which room?
Since not all coax jacks in the rooms are connected to a tv, it's not
just a matter of disconnecting one cable after another from the
splitter and seeing which tv loses its signal.

"Since not all coax jacks in the rooms are connected to a tv,
it's not just a matter of disconnecting one cable after another
from the splitter and seeing which tv loses its signal"
I can think of two ways right away. The way I would do it is
to get a small TV and conenct it to a cable outlet. Turn the sound
up high. Go in the attic and perhaps with a helper listening
disconnect one coax at a time. bingo.

the hard way would be to use a volt-ohm meter. disconnect all the coax
in the attic and jumper one outlet
across itself. then check in the attic for the line with 0 resistance.
....thehick

And now the question: is there a way to determine, without buying
expensive equipment, which cable in the attic leads to which room?
Since not all coax jacks in the rooms are connected to a tv, it's not
just a matter of disconnecting one cable after another from the
splitter and seeing which tv loses its signal.

Cut a small cable in two.. On one cut end wire up a 9v battery connector. On
the other cut end wire up a buzzer, or at least strip it so you can use a
meter to test the wire and shield.

Hook the 9v at the wall outlet. Go up to the splitter and check each lead
that comes up to the splitter. When you buzz, or get a 9v reading, you've
found that room.

wrote:

I have what I think is an unsual question which I couldn't find an
answer to: in my attic there is a coax splitter with several coax
outputs to coax cables which snake into the ceiling and disappear in
the boweles of the house. They are all of the same color and have no
identifying marks. In the house itself, there are coax jacks in
several rooms.

And now the question: is there a way to determine, without buying
expensive equipment, which cable in the attic leads to which room?
Since not all coax jacks in the rooms are connected to a tv, it's not
just a matter of disconnecting one cable after another from the
splitter and seeing which tv loses its signal.

Hi,
I saw cable guy using a 9V battery with coax connector and buzzer to
trace coax. Simple but works.
Tony

also: cable tv company here will upgrade your splitters and replace the
cable ends from the pole to your jacks to deliver a nice picture to
your cable tv's.
and: maybe time to break down and buy a digital multimeter for $25.
look what you can fix with it at:
http://www.repairfaq.org/REPAIR/F_ts...tml#TSHOOT_014

Tony Hwang wrote:

wrote:

I have what I think is an unsual question which I couldn't find an
answer to: in my attic there is a coax splitter with several coax
outputs to coax cables which snake into the ceiling and disappear in
the boweles of the house. They are all of the same color and have no
identifying marks. In the house itself, there are coax jacks in
several rooms.

And now the question: is there a way to determine, without buying
expensive equipment, which cable in the attic leads to which room?
Since not all coax jacks in the rooms are connected to a tv, it's not
just a matter of disconnecting one cable after another from the
splitter and seeing which tv loses its signal.

Hi,
I saw cable guy using a 9V battery with coax connector and buzzer to
trace coax. Simple but works.
Tony
.... as long as there's not another splitter between the battery and the
buzzer.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

Sorry for the newbie question, but what happens if there is a splitter?


Also, is possible to tell - and if so, how - if there are one or more
splitters between the attic and the room?

And, another also, will the presense of one or more splitters affect
the other approach suggested by others on this thread (volt-ohm/multi
meter)?

At least thehick's other idea - using a portable tv - should still
work...

wrote:

Sorry for the newbie question, but what happens if there is a splitter?


Also, is possible to tell - and if so, how - if there are one or more
splitters between the attic and the room?

And, another also, will the presense of one or more splitters affect
the other approach suggested by others on this thread (volt-ohm/multi
meter)?

At least thehick's other idea - using a portable tv - should still
work...

If there's another splitter, then it depends on the particular splitter
in question -- some will pass DC, others won't. If it doesn't pass DC,
then neither the buzzer nor the meter will register the battery's
voltage.

As for using a TV, it'll introduce some ambiguity there, too, since you
might have two (or more) equally good signals.

If you have the same number of wires in the attic as wall connections,
there's probably not another splitter.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

"Noozer" wrote in message
news:cJzAf.300933$2k.177325@pd7tw1no...
:
: And now the question: is there a way to determine, without
buying
: expensive equipment, which cable in the attic leads to which
room?
: Since not all coax jacks in the rooms are connected to a tv,
it's not
: just a matter of disconnecting one cable after another from
the
: splitter and seeing which tv loses its signal.
:
: Cut a small cable in two.. On one cut end wire up a 9v battery
connector. On
: the other cut end wire up a buzzer, or at least strip it so you
can use a
: meter to test the wire and shield.
:
: Hook the 9v at the wall outlet. Go up to the splitter and check
each lead
: that comes up to the splitter. When you buzz, or get a 9v
reading, you've
: found that room.
:
:
Good grieg, Charlie Brown! That's the hard way, and destructive,
too. Read the previous post - much easier and cleaner and more
dependaghle and a lot less destructvie.

CJT wrote:
wrote:

Sorry for the newbie question, but what happens if there is a splitter?


Also, is possible to tell - and if so, how - if there are one or more
splitters between the attic and the room?

And, another also, will the presense of one or more splitters affect
the other approach suggested by others on this thread (volt-ohm/multi
meter)?

At least thehick's other idea - using a portable tv - should still
work...

If there's another splitter, then it depends on the particular splitter
in question -- some will pass DC, others won't. If it doesn't pass DC,
then neither the buzzer nor the meter will register the battery's
voltage.

As for using a TV, it'll introduce some ambiguity there, too, since you
might have two (or more) equally good signals.

If you have the same number of wires in the attic as wall connections,
there's probably not another splitter.


If there were more splitters, it would be unlikely that they would be
hidden away somewhere. Splitters and connectors do occasionally fail and
they would have to be accessible for service. Depends on the
intelligence of the installer.

Bob

If the cable was daisy chained as was the custom years ago, there could
be a splitter at every outlet. My last house had a run with 9 splitters
in it. Needless to say, it didn't do very well with a broadband
connection!

From:RobertM


CJT wrote:
wrote:

Sorry for the newbie question, but what happens if there is a
splitter? Also, is possible to tell - and if so, how - if there are
one or
more splitters between the attic and the room?

And, another also, will the presense of one or more splitters affect
the other approach suggested by others on this thread
(volt-ohm/multi meter)?

At least thehick's other idea - using a portable tv - should still
work...

If there's another splitter, then it depends on the particular
splitter in question -- some will pass DC, others won't. If it
doesn't pass DC, then neither the buzzer nor the meter will register
the battery's voltage.

As for using a TV, it'll introduce some ambiguity there, too, since
you might have two (or more) equally good signals.

If you have the same number of wires in the attic as wall
connections, there's probably not another splitter.


If there were more splitters, it would be unlikely that they would be
hidden away somewhere. Splitters and connectors do occasionally fail
and they would have to be accessible for service. Depends on the
intelligence of the installer.

Bob

wrote in message
ups.com...
I have what I think is an unsual question which I couldn't find an
answer to: in my attic there is a coax splitter with several coax
outputs to coax cables which snake into the ceiling and disappear in
the boweles of the house. They are all of the same color and have no
identifying marks. In the house itself, there are coax jacks in
several rooms.

And now the question: is there a way to determine, without buying
expensive equipment, which cable in the attic leads to which room?
Since not all coax jacks in the rooms are connected to a tv, it's not
just a matter of disconnecting one cable after another from the
splitter and seeing which tv loses its signal.


Let's assume there are no other splitters involved.
Forget the battery method.
Go to RadioShack or equivalent and buy a 75 ohm terminator.
If you don't own a test meter, get the cheapest one you can find that
measures resistance.
Disconnect all the sets that are attached to the cable system
Put the terminator on one wall outlet.
At the splitter disconnect, all the cables.
Take the meter and at the splitter end find the cable that measures about 75
ohms between the center pin of the cable connector and the outside of the
cable connector.
Tag both ends of that cable.
Move the terminator to the next wall outlet and repeat.
Having an assistant who can move the terminator around and communicate to
the attic is a great time and effort saver.

Charlie

On 21 Jan 2006 15:38:48 -0800, wrote:

I have what I think is an unsual question which I couldn't find an
answer to: in my attic there is a coax splitter with several coax
outputs to coax cables which snake into the ceiling and disappear in
the boweles of the house. They are all of the same color and have no
identifying marks. In the house itself, there are coax jacks in
several rooms.

And now the question: is there a way to determine, without buying
expensive equipment, which cable in the attic leads to which room?
Since not all coax jacks in the rooms are connected to a tv, it's not
just a matter of disconnecting one cable after another from the
splitter and seeing which tv loses its signal

Unless there is a complet floor in the attic, I would follow the wires
into the ceiling, lifting the insulation a bit until I find where they
go down into a wall, from the top. In the attic, a wall looks like
the broad side of a 2x4. The wire is not likely to stray too much
once it heads into the wall. The ones you can't trace this way, you
can trace with the other methods given.

Remove NOPSAM to email me. Please let
me know if you have posted also.

You can even just use an alligator switch to short the center conductor
to the side and check for 0 ohms.

From:Charlie Bress


wrote in message
ups.com...
I have what I think is an unsual question which I couldn't find an
answer to: in my attic there is a coax splitter with several coax
outputs to coax cables which snake into the ceiling and disappear in
the boweles of the house. They are all of the same color and have no
identifying marks. In the house itself, there are coax jacks in
several rooms.

And now the question: is there a way to determine, without buying
expensive equipment, which cable in the attic leads to which room?
Since not all coax jacks in the rooms are connected to a tv, it's not
just a matter of disconnecting one cable after another from the
splitter and seeing which tv loses its signal.


Let's assume there are no other splitters involved.
Forget the battery method.
Go to RadioShack or equivalent and buy a 75 ohm terminator.
If you don't own a test meter, get the cheapest one you can find that
measures resistance.
Disconnect all the sets that are attached to the cable system
Put the terminator on one wall outlet.
At the splitter disconnect, all the cables.
Take the meter and at the splitter end find the cable that measures
about 75 ohms between the center pin of the cable connector and the
outside of the cable connector.
Tag both ends of that cable.
Move the terminator to the next wall outlet and repeat.
Having an assistant who can move the terminator around and
communicate to the attic is a great time and effort saver.

Charlie

wrote in message
ups.com...
I have what I think is an unsual question which I couldn't find an
answer to: in my attic there is a coax splitter with several coax
outputs to coax cables which snake into the ceiling and disappear in
the boweles of the house. They are all of the same color and have no
identifying marks. In the house itself, there are coax jacks in
several rooms.

And now the question: is there a way to determine, without buying
expensive equipment, which cable in the attic leads to which room?
Since not all coax jacks in the rooms are connected to a tv, it's not
just a matter of disconnecting one cable after another from the
splitter and seeing which tv loses its signal.

Other posters have given you reasonable suggestions for identifying the
cables. But I'm wondering why it matters as long as each outlet is feeding
the same signal from the same source -- the splitter.

A caveat --

In a setup such as yours, each unused outlet should have a 75 ohm
terminator. Radio Shack has them. Unterminated cables can mess up the
signal to the active devices on the network.

SJF

"SJF" wrote in message
news:aDEAf.9492$bF.1572@dukeread07...

wrote in message
ups.com...
I have what I think is an unsual question which I couldn't find an
answer to: in my attic there is a coax splitter with several coax
outputs to coax cables which snake into the ceiling and disappear in
the boweles of the house. They are all of the same color and have no
identifying marks. In the house itself, there are coax jacks in
several rooms.

And now the question: is there a way to determine, without buying
expensive equipment, which cable in the attic leads to which room?
Since not all coax jacks in the rooms are connected to a tv, it's not
just a matter of disconnecting one cable after another from the
splitter and seeing which tv loses its signal.

Other posters have given you reasonable suggestions for identifying the
cables. But I'm wondering why it matters as long as each outlet is
feeding the same signal from the same source -- the splitter.

A caveat --

In a setup such as yours, each unused outlet should have a 75 ohm
terminator. Radio Shack has them. Unterminated cables can mess up the
signal to the active devices on the network.

SJF

That goes for any unused connections on the spliter(s) as well.

"Other posters have given you reasonable suggestions for identifying
the
cables. But I'm wondering why it matters as long as each outlet is
feeding
the same signal from the same source -- the splitter. "

Interesting you should ask (and, btw, you seem to be the first to do
so...). Anyway, a little off topic, but the reason for the question is
this: the cable company's feed starts from the attic and is being split
into various rooms as I described. What I would like to do is intall in
the attic an HTDV over-the-air antenna and feed the signal from that to
an HDTV in one of the rooms.

I don't want to run a new cable from the attic thru the second floor to
the first floor (where the HDTV is located); I just don't have the
skills (and probably tools) required for that kind of job. So, in my
infinite wisdom, I figured that if I can determine which cable goes to
the room in question, I'll just disconnect it from the splitter and
connect it to the OTA HDTV antenna in the attic (using a coax coupler)
and to the HDTV in the room and voila! OTA HDTV reception.

I understand that by doing that I give up regular cable reception in
that room but (1) it's a problem for another day and (2) it's not
really much of a problem anyway since I don't intend to user that for
the usual cable fare.

So that's the reason....

Well, that's a departure from the other proposals Just to be on the
safe side, I'm going to get tomorrow both a buzzer and a 75 ohm
terminator!

I already have a 9v battery and even a multimeter - analog,
unfortunately, but it does measure resistance, so I should be all set
(assuming by wife agrees to act as the assistant...)

As an aside, I must say it NEVER occured to me how useful a multimeter
is. Talk about learning something new every day.

" A caveat --

In a setup such as yours, each unused outlet should have a 75 ohm
terminator. Radio Shack has them. Unterminated cables can mess up the
signal to the active devices on the network.

SJF

That goes for any unused connections on the spliter(s) as well. "

Wow, for someone who is regulary considered by his friends as a more or
less maven, I now feel unbelievably ignorant ): I guess ignorance is
relative... I have never heard of 75 ohm terminators, nor of the
problems caused by unterminated cables and unused connections on
splitters. As I mentioned in another response - learn something new
every day.

The center conductor of the coax is acts a small broadcast antenna (as
well as a receiver) the outer shield serves to contain the signal on the
center conductor to prevent both radiated signal leakage and reception
of over-the-air signals. The exposed end of the cable or splitter
connection is breaks the "seal" on the system and allows for leakage and
reception of unwanted signals. The terminator acts like a lid on jar and
maintains the cables impedance.




" A caveat --

In a setup such as yours, each unused outlet should have a 75 ohm
terminator. Radio Shack has them. Unterminated cables can mess up
the signal to the active devices on the network.

SJF

That goes for any unused connections on the spliter(s) as well. "

Wow, for someone who is regulary considered by his friends as a more
or less maven, I now feel unbelievably ignorant ): I guess ignorance
is relative... I have never heard of 75 ohm terminators, nor of the
problems caused by unterminated cables and unused connections on
splitters. As I mentioned in another response - learn something new
every day.

Good guess.
Wrong reason. The unterminated piece of cable, either open or shorted,
creates a phenomenon called a standing wave. Depending on the length of the
offending cable and whether it is opened or shorted, the wave can raise the
dickens with the right signals. Terminating the cable in the correct
impedance doesn't let the standing wave be created.

Take a look at
http://www.glenbrook.k12.il.us/GBSSC...es/u10l4b.html
It talks about standing waves in a string, but the concept is similar for
liquids and radio waves.

Charlie

"BruceR" wrote in message
...
The center conductor of the coax is acts a small broadcast antenna (as
well as a receiver) the outer shield serves to contain the signal on the
center conductor to prevent both radiated signal leakage and reception of
over-the-air signals. The exposed end of the cable or splitter connection
is breaks the "seal" on the system and allows for leakage and reception of
unwanted signals. The terminator acts like a lid on jar and maintains the
cables impedance.




" A caveat --

In a setup such as yours, each unused outlet should have a 75 ohm
terminator. Radio Shack has them. Unterminated cables can mess up
the signal to the active devices on the network.

SJF

That goes for any unused connections on the spliter(s) as well. "

Wow, for someone who is regulary considered by his friends as a more
or less maven, I now feel unbelievably ignorant ): I guess ignorance
is relative... I have never heard of 75 ohm terminators, nor of the
problems caused by unterminated cables and unused connections on
splitters. As I mentioned in another response - learn something new
every day.

wrote in message
oups.com...
"Other posters have given you reasonable suggestions for identifying
the
cables. But I'm wondering why it matters as long as each outlet is
feeding
the same signal from the same source -- the splitter. "

Interesting you should ask (and, btw, you seem to be the first to do
so...). Anyway, a little off topic, but the reason for the question is
this: the cable company's feed starts from the attic and is being split
into various rooms as I described. What I would like to do is intall in
the attic an HTDV over-the-air antenna and feed the signal from that to
an HDTV in one of the rooms.

I don't want to run a new cable from the attic thru the second floor to
the first floor (where the HDTV is located); I just don't have the
skills (and probably tools) required for that kind of job. So, in my
infinite wisdom, I figured that if I can determine which cable goes to
the room in question, I'll just disconnect it from the splitter and
connect it to the OTA HDTV antenna in the attic (using a coax coupler)
and to the HDTV in the room and voila! OTA HDTV reception.

I understand that by doing that I give up regular cable reception in
that room but (1) it's a problem for another day and (2) it's not
really much of a problem anyway since I don't intend to user that for
the usual cable fare.

So that's the reason....

Logical reason -- and a good work-around.

SJF

Mmmmm!

Any unterminated cable looks like reactance to the rest of the circuit.
How much effect it has mainly depends on whats between it and the other
sections. A splitter like what one finds in motels with long runs has
only a small signal going to the TV and most of it continuing to the
next splitter. There is minimal effect leaving this configuration
unterminated. If however you are splitting the power in half (like most
home splitters) the effect will be greater. Worst case it could look
like a short circuit on one output port of the splitter, thus lowering
the other o/p port somewhat. You can also increase line losses by the
increased line VSWR but this is a very small figure next to the coax
resistive losses.

The simple rule is if you think you have a problem, try terminating and
check the effect on all TV channels. If you dont want to buy a
terminator just add an extra bit of coax (to the unterminated one) for a
test. If you have a strong signal in your area you may not need worry.
The biggest problems I have seen with CATV systems is the lack of good
connector earth connections yielding bleedthrough and low s/n
performance. Coax will only radiate or receive signal direct into the
jacket if there is a current inbalance inner to outer conductor. This
generally mean an asymmetric source or load. An open, shorted or high
line VSWR doesnt cause this problem.

An effective "short" or "open" situation only exists where the length of
the unterminated cable is either odd multiple of a 1/4 wavelength
(short) or multiples of a half wavelength (open) for ONLY the frequency
of interest. If the frequency doubles the wavelength halves. That gets
very complex with so many different TV freqs. This is in fact a very
good way of making a filter. If you were for example watching TV from
both a very weak and very strong station and needed a masthead preamp
for the weak one, chances are the strong signal will break through. If
you attach a piece of coax cut to a 1/4 wavelength of the strong station
at the preamp input it will null it by maybe 20-30dB. Note that the
other end of the coax needs to be waterproofed and the length modified
(shorter) by the velocity factor of the coax (between 0.66 and 0.82 or
so. Foam RG6 would be about 0.82)

Apologies for the waffle. I couldnt resist!

Cheers Bob


Charlie Bress wrote:
Good guess.
Wrong reason. The unterminated piece of cable, either open or shorted,
creates a phenomenon called a standing wave. Depending on the length of the
offending cable and whether it is opened or shorted, the wave can raise the
dickens with the right signals. Terminating the cable in the correct
impedance doesn't let the standing wave be created.