Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Default Coaxial cable without a connector

I've got the main cable-tv cable leading from outside the apartment
into an opening in my storage room. That cable is attached to a
splitter so I can join the four cables which run to the four jacks
throughout my apartment.

One of those four cables does not have an RF connector on end of it.
The cable is just bare, with the pin (core) and the various sheathing
of the cable exposed.

Even without a connector to screw the cable onto the splitter
securely, the signal works good enough if I just slide the pin into
the spitter.

My question: will this create any type of hazard? The cable tv
company wants to charge for a housecall just to come out and put a new
connector on the end of this cable. But I'm wondering if it's safe
enough just to stick the pin in and wrap some electrical tape around
it to hold it in place? Anyone know?
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Default Coaxial cable without a connector


wrote in message
...
I've got the main cable-tv cable leading from outside the apartment
into an opening in my storage room. That cable is attached to a
splitter so I can join the four cables which run to the four jacks
throughout my apartment.

One of those four cables does not have an RF connector on end of it.
The cable is just bare, with the pin (core) and the various sheathing
of the cable exposed.

Even without a connector to screw the cable onto the splitter
securely, the signal works good enough if I just slide the pin into
the spitter.

My question: will this create any type of hazard? The cable tv
company wants to charge for a housecall just to come out and put a new
connector on the end of this cable. But I'm wondering if it's safe
enough just to stick the pin in and wrap some electrical tape around
it to hold it in place? Anyone know?


It's just a small signal to your TV, no high voltages or currents present.
Having said that, couldn't you buy a connector and fit it yourself?
The signal may be poor or intermittant, the outer shielding should be
connected also.


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Default Coaxial cable without a connector



My question: will this create any type of hazard? The cable tv
company wants to charge for a housecall just to come out and put a new
connector on the end of this cable. But I'm wondering if it's safe
enough just to stick the pin in and wrap some electrical tape around
it to hold it in place? Anyone know?


No hazard but if you want to do it right:
http://www.satcure.co.uk/tech/fconn.htm


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Default Coaxial cable without a connector

Charles wrote:
My question: will this create any type of hazard? The cable tv
company wants to charge for a housecall just to come out and put a new
connector on the end of this cable. But I'm wondering if it's safe
enough just to stick the pin in and wrap some electrical tape around
it to hold it in place? Anyone know?


No hazard but if you want to do it right:
http://www.satcure.co.uk/tech/fconn.htm


Granted, no hazard...in a similar situation, though, an improperly
terminated coax plug in my house caused a lot of ghosting on the rest of
the system. Once I properly dressed the cable, applied a connector (new
types require nothing more than a pair of wirecutters or even a knife to
install), the picture on the rest of the sets in the house cleared up
considerably.

What was happening was the strong over-the-air signal was leaking into
that unterminated connection. Where local channels corresponded to
cable channels, the result was a 'pre-echo' on the screen. IOW, there
was a ghost of the picture to the left of desired picture...messed with
the sound, as well. This is similar to multipath distortion when a TV
signal takes multiple routes on its way to an antenna. The different
paths results in multiple instances of the picture displayed, separated
by a distance determined by the time delay of each arriving at the set.

jak


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Default Coaxial cable without a connector

In article ,

One of those four cables does not have an RF connector on end of it.
The cable is just bare, with the pin (core) and the various sheathing
of the cable exposed.

Even without a connector to screw the cable onto the splitter
securely, the signal works good enough if I just slide the pin into
the spitter.

My question: will this create any type of hazard?


It can easily create RF interference problems, both to and from the
cable-TV system.

Cable TV uses many frequencies, on the cable, which are not "broadcast
television" frequencies - they're assigned to other over-the-air uses,
such as aircraft communications, police and fire, amateur radio, etc.
Cable can use them without interfering with over-the-air users
(normally) because cable TV is a "closed system". The outer sheath of
the cable acts as a shield - the signals stay on the inside of the
cable (the center conductor, and the inside of the shield) and don't
travel to the outside.

If you break the cable open, and don't connect the shield properly,
you "open" the cable system. Signals inside the cable can "wrap
around" onto the outside of the shield and can be radiated out into
the neighborhood, causing RF interference with the assigned
over-the-air users of these frequencies. Interference can also travel
in the other direction - if a police or fire or ham-radio transmitter
is operated nearby, the strong signal can leak into the cable and
interfere with cable-TV reception on these channels. In a severe
case, the outside interference can travel as far as a cable
distribution amplifier, be boosted, and can interfere with or shut
down cable-TV reception over a wide area. The worse case I've heard
of involved a cable leak near the cable-TV company's headquarters... a
nearby transmission saturated the amplifiers and shut down the whole
town's entire cable-TV feed.

It's important to maintain the integrity of the cable TV system and
prevent "leaks". In fact, the cable TV companies are under legal
obligation to do so, and they usually have "leak detector" checks of
each neighborhood occasionally. If they find that your house is the
source of a leak, they may insist that you fix it (or let them do so)
or may disconnect your cable feed until it's fixed.

I encourage you to install the proper "F" connector. They're
available in both crimp-on and twist-on styles, aren't expensive, and
should be available at your local hardware store.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!
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Default Coaxial cable without a connector

On Feb 9, 1:33*pm, "gonzo" wrote:
It's just a small signal to your TV, no high voltages or currents present.
Having said that, couldn't you buy a connector and fit it yourself?
The signal may be poor or intermittant, the outer shielding should be
connected also.- Hide quoted text -


Thanks, Gonzo (and Baron). Yes, I will try to find a connector which
I can install. My main concern was whether I could use that cable for
a while BEFORE I got around to getting a new connector for it.
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Default Coaxial cable without a connector

On Feb 9, 2:03*pm, "Charles" wrote:
No hazard but if you want to do it right:http://www.satcure.co.uk/tech/fconn.htm


Now we're talkin'. Thanks so much for that.
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Default Coaxial cable without a connector

On Feb 9, 7:49*pm, (Dave Platt) wrote:

I encourage you to install the proper "F" connector. *They're
available in both crimp-on and twist-on styles, aren't expensive, and
should be available at your local hardware store.


Yikes. Talk about "for want of a...etc, etc". Assuming I can find a
connector at the local shop, I promise I'll get it on asap.
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Default Coaxial cable without a connector


wrote in message
...
On Feb 9, 1:33 pm, "gonzo" wrote:
It's just a small signal to your TV, no high voltages or currents present.
Having said that, couldn't you buy a connector and fit it yourself?
The signal may be poor or intermittant, the outer shielding should be
connected also.- Hide quoted text -


Thanks, Gonzo (and Baron). Yes, I will try to find a connector which
I can install. My main concern was whether I could use that cable for
a while BEFORE I got around to getting a new connector for it.




Sure Why not. I think the risk for interference that others were talking
about is minimal. I have a tv that is hooked up that way right now, simply
because I lost the connector and the tv is in my workshop. It doesn't get
used too much so I really don't care if the picture is a bit snowy on some
channels. If I were you I'd get a connector just to make sure I had a good
picture.

Mike




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Default Coaxial cable without a connector

"Michael Kennedy" wrote in
:


wrote in message
...
On Feb 9, 1:33 pm, "gonzo" wrote:
It's just a small signal to your TV, no high voltages or currents
present. Having said that, couldn't you buy a connector and fit it
yourself? The signal may be poor or intermittant, the outer shielding
should be connected also.- Hide quoted text -


Thanks, Gonzo (and Baron). Yes, I will try to find a connector which
I can install. My main concern was whether I could use that cable for
a while BEFORE I got around to getting a new connector for it.




Sure Why not. I think the risk for interference that others were talking
about is minimal.


What you are doing is similar to the guy that goes out on new years eve
and fires his gun in the air to celebrate. He has no way to know where it
will come down. People die every year because of such things.

I have a tv that is hooked up that way right now, simply
because I lost the connector and the tv is in my workshop.


You have no way to know what it might interfere with.

It doesn't get
used too much so I really don't care if the picture is a bit snowy on
some channels.


It does NOT matter if the set is turned on or not. It only matters if
there are signals on the cable!

If I were you I'd get a connector just to make sure I had a good
picture.


One of the cable TV signals might interfere with vital communications,
such as with fire, police or aircraft communications or navigation.

Now that you KNOW that you may be radiating signals that could interfere
with communications, you have an obligation to cease.

Deliberate interference with radio communications is a crime.




--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

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Default Coaxial cable without a connector



One of the cable TV signals might interfere with vital communications,
such as with fire, police or aircraft communications or navigation.

Now that you KNOW that you may be radiating signals that could interfere
with communications, you have an obligation to cease.

Deliberate interference with radio communications is a crime.



Interference in such a scenario is *extremely* unlikely. The power level is
low, and a small unshielded section is a horrible antenna. On top of that,
this would not be "deliberate interference". Putting a connector on there is
a good idea, it's the only right way to do it, but there's no need for
paranoia, there's nothing you could reasonably do that will cause any
undesired interference to anything else.


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Default Coaxial cable without a connector

"James Sweet" wrote in
news:[email protected]:



One of the cable TV signals might interfere with vital communications,
such as with fire, police or aircraft communications or navigation.

Now that you KNOW that you may be radiating signals that could
interfere with communications, you have an obligation to cease.

Deliberate interference with radio communications is a crime.



Interference in such a scenario is *extremely* unlikely. The power level
is low, and a small unshielded section is a horrible antenna. On top of
that, this would not be "deliberate interference". Putting a connector
on there is a good idea, it's the only right way to do it, but there's
no need for paranoia, there's nothing you could reasonably do that will
cause any undesired interference to anything else.


Try listening on the shortwave radio bands near my house. The noise from
switching power supplies, computers, dimmer switches, TV local oscillators,
power line leakage AND cable leakage makes it impossible to hear any weak
signals using a radio receiver that was quite fine in the 1960's {the Drake
2B receiver}. My Electraft K2/100 does much better but the noise blanker
MUST be used, otherwise only the strongest signals can be heard.

The fault is not the receiver, it is the high level of noises.

I do NOT have nor use cable TV. I get my TV signals 'off the air' with
rabbit ears. I can often pick up sufficient leakage from the cable TV to
view some programs.
There are strong 'herring bone patterns on even the strongest local
stations' due to cable leakage of signals from the cable.

My 2 meter ham transceiver in my car often picks up strong interference on
some frequencies as I drive around town.
Some of the signals seem to be 'point of sale' devices that are radiating
in the 144 MHz band.
Some sound like TV video and some sound like wide band FM.

Of course, some of these are 'mixing products' due to resonant structures
that happen to have non linear conductance {rusty joints) that are picking
up TV and other radio signals, mixing them together and radiating the
products.

I disagree with your assessment of '*extremely* unlikely'. I estimate it to
be "unacceptably likely".

The 'small unshielded section' is not the antenna.
The antenna is the shield which is not connected at one end and the object
at the end of the center conductor.

The shielded cable can be many wavelengths long.

The improper termination at the end causes standing waves. These standing
waves appear on the outside of the coax. The coax radiates.

The entire TV set also serves as a radiating device that is on the end of
that piece of coax.

Take a transmitter and feed it into a long piece of coax.
At the end of that coax, hang a metal plate that is 19 inches by 19 inches.

Feed it with 145 MHz signal.

You will have a pretty effective radiator.

Couple to the metal plate through a capacitor of a couple of nF and it will
still work rather well.

THAT is exactly what you have when you do not connect the shield on that
cable to the TV.

Here is a test you can do with a VCR and two TVs:

Make a 'bad hookup' from the VCR to a TV in one room. Play back a tape on
the VCR [putting a signal onto channel 2 or 3]

Go to another room with a TV with rabbit ears and see if you can see any
signs of the VCR's signals 'over the air'.

I have seen signals from VCR's because people do not realize they are
broadcasting.




--
bz 73 de N5BZ k

I have held FCC 1st class Radio Telephone and 2nd class Radio Telegraph
licences with Ship Radar Endorsement, TEA Certified Electronic Technician
in Radio TV, Audio and Industrial Electronics.

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

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Default Coaxial cable without a connector

bz wrote:

snip

Here is a test you can do with a VCR and two TVs:

Make a 'bad hookup' from the VCR to a TV in one room. Play back a tape on
the VCR [putting a signal onto channel 2 or 3]

Go to another room with a TV with rabbit ears and see if you can see any
signs of the VCR's signals 'over the air'.

I have seen signals from VCR's because people do not realize they are
broadcasting.


VCR modulators make fairly good transmitters. I once lived a few months
in temporary housing, with little more than a TV and a couch for
amenities. My neighbor hooked up her VCR to the TV by feeding the
modulator output to the 300 ohm TV antenna input through a balun.

So far, so good, except she left the rabbit ears connected to the same
300 ohm terminals (in parallel with the VCR output). This was pre-cable
era in the area...early 80's.

I was able to get an acceptable signal from her VCR in the next
apartment--through the wall and several meters away--by simply tuning my
set (rabbit ears, again) to channel 3.

She had a fairly good porn collection. G

jak
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Default Coaxial cable without a connector

jakdedert wrote in
:

bz wrote:

snip

Here is a test you can do with a VCR and two TVs:

Make a 'bad hookup' from the VCR to a TV in one room. Play back a tape
on the VCR [putting a signal onto channel 2 or 3]

Go to another room with a TV with rabbit ears and see if you can see
any signs of the VCR's signals 'over the air'.

I have seen signals from VCR's because people do not realize they are
broadcasting.


VCR modulators make fairly good transmitters. I once lived a few months
in temporary housing, with little more than a TV and a couch for
amenities. My neighbor hooked up her VCR to the TV by feeding the
modulator output to the 300 ohm TV antenna input through a balun.

So far, so good, except she left the rabbit ears connected to the same
300 ohm terminals (in parallel with the VCR output). This was pre-cable
era in the area...early 80's.

I was able to get an acceptable signal from her VCR in the next
apartment--through the wall and several meters away--by simply tuning my
set (rabbit ears, again) to channel 3.

She had a fairly good porn collection. G


That sounds like '"broad" casting' to me.




--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

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