Need help - no signal from TV antenna in the attic
ymg...@excite.com
I just moved in to the new house. There is a 4-way coax splitter in
the attic, which has one input and four outputs (to different rooms).
I know that previous owners had a cable (from the cable company). It
looks like the cable was going into the same splitter in the attic,
and then routed to rooms downstairs.
I want to use the TV antenna in the attic.
I tried connecting the TV antenna to splitter's input – absolutely no
signal is getting to TVs downstairs. I also connected the antenna to
each of splitter’s outputs (which go to TVs) – exactly the same
outcome - not even a change in a static when I plug in the antenna.
I bought a TV signal inline amplifier from RadioShack – absolutely no
difference.
However, if I drop a 100' coax cable directly from the antenna in the
attic to the TV downstairs (bypassing the splitter and all of the home
cable wiring), the picture is crisp and perfect.
Can I run some tests to ensure cable continuation (from the attic to
rooms downstairs).
Does anybody know how I can get the signal from the antenna in the
attic to TVs downstairs?
Thank you.
Bryce
> Hi,
> I just moved in to the new house. There is a 4-way coax splitter in
> the attic, which has one input and four outputs (to different rooms).
> I know that previous owners had a cable (from the cable company). It
> looks like the cable was going into the same splitter in the attic,
> and then routed to rooms downstairs.
> I want to use the TV antenna in the attic.
> I tried connecting the TV antenna to splitter's input ? absolutely no
> signal is getting to TVs downstairs. I also connected the antenna to
> each of splitter?s outputs (which go to TVs) ? exactly the same
> outcome - not even a change in a static when I plug in the antenna.
> I bought a TV signal inline amplifier from RadioShack ? absolutely no
> difference.
> However, if I drop a 100' coax cable directly from the antenna in the
> attic to the TV downstairs (bypassing the splitter and all of the home
> cable wiring), the picture is crisp and perfect.
> Can I run some tests to ensure cable continuation (from the attic to
> rooms downstairs).
> Does anybody know how I can get the signal from the antenna in the
> attic to TVs downstairs?
> Thank you.
Have you looked behind the wall plates downstairs? Perhap a band-reject
filter? Are you certain the cables from the attic don't go somewhere
else before going to the downstairs TVs?
To check continuity: first use an ohmmeter to verify that the cable reads
open-circuit at DC in the attic. Then connect a 1.5v battery across the
disconnected cable in the attic and check for 1.5v downstairs.
If all else fails, move the TVs up to the attic.
GMAN
>Hi,
>I just moved in to the new house. There is a 4-way coax splitter in
>the attic, which has one input and four outputs (to different rooms).
>I know that previous owners had a cable (from the cable company). It
>looks like the cable was going into the same splitter in the attic,
>and then routed to rooms downstairs.
>I want to use the TV antenna in the attic.
>signal is getting to TVs downstairs. I also connected the antenna to
>outcome - not even a change in a static when I plug in the antenna.
>difference.
>However, if I drop a 100' coax cable directly from the antenna in the
>attic to the TV downstairs (bypassing the splitter and all of the home
>cable wiring), the picture is crisp and perfect.
>Can I run some tests to ensure cable continuation (from the attic to
>rooms downstairs).
>Does anybody know how I can get the signal from the antenna in the
>attic to TVs downstairs?
>Thank you.
Try a female/female rf connector from radio shack. Bypassing the splitter to
see if it sends signal to each tv's
If that doesnt work, then suspect the cable from the Antenna to the splitter
is bad??? If it does work, get a new splitter.
Mikepier
You did not mention, is this for HDTV? If the cable is old like RG58
or 59, it might not be able to handle the UHF bandwidth of HD
channels. If the 100ft cable you tested was RG6, and it worked, that
would make sense. But as the other poster said, try testing the cable
and see if there is continuity.
UCLAN
>> Hi, I just moved in to the new house. There is a 4-way coax splitter in
>> the attic, which has one input and four outputs (to different rooms). I
>> know that previous owners had a cable (from the cable company). It looks
>> like the cable was going into the same splitter in the attic, and then
>> routed to rooms downstairs. I want to use the TV antenna in the attic. I
>> tried connecting the TV antenna to splitter's input =96 absolutely no
>> signal is getting to TVs downstairs. I also connected the antenna to each
>> of splitter=92s outputs (which go to TVs) =96 exactly the same outcome -
>> not even a change in a static when I plug in the antenna. I bought a TV
>> signal inline amplifier from RadioShack =96 absolutely no difference.
>> However, if I drop a 100' coax cable directly from the antenna in the
>> attic to the TV downstairs (bypassing the splitter and all of the home
>> cable wiring), the picture is crisp and perfect. Can I run some tests to
>> ensure cable continuation (from the attic to rooms downstairs). Does
>> anybody know how I can get the signal from the antenna in the attic to
>> TVs downstairs? Thank you.
>
> Try a female/female rf connector from radio shack. Bypassing the splitter
> to see if it sends signal to each tv's
Sounds like he already did:
"However, if I drop a 100' coax cable directly from the antenna in the
attic to the TV downstairs (bypassing the splitter and all of the home
cable wiring), the picture is crisp and perfect."
*If* we take what he wrote above verbatim, I would suspect the cable from
the antenna to the splitter. I would try his 100' bypass cable again, but
this time include the antenna feed cable in the path. If it doesn't work,
it's that lead cable.
stra...@yahoo.com
> You did not mention, is this for HDTV? If the cable is old like
RG58
> or 59, it might not be able to handle the UHF bandwidth of HD
> channels. If the 100ft cable you tested was RG6, and it worked,
that
> would make sense. But as the other poster said, try testing the
cable
> and see if there is continuity.
What??? RG-58 is 50 ohm IIRC and while RG-59 isn't the best coax, it
will pass HDTV RF properly. The best of the RG-59 is Belden 1505 and
is nearly as good as RG-6. I would look for corroded connections at
every junction point and replace when found. Any rodents chomping
through the cables?
G²
Ron
Or, just use screw the bypass directly into the splitter.
RickMerrill
> Hi,
> I just moved in to the new house. There is a 4-way coax splitter in
> the attic, which has one input and four outputs (to different rooms).
Every 4-way I have seen has actually been an amplifier - look at it
from all sides and see if there is a power connection: it would probably
be DC power from a 'wall-wart' located elsewhere.
Ron
> ymg...@excite.com wrote:
> > Hi,
> > I just moved in to the new house. There is a 4-way coax splitter in
> > the attic, which has one input and four outputs (to different rooms).
>
> Every 4-way I have seen has actually been an amplifier
Now you've seen one that isn't :)
http://i126.photobucket.com/albums/p96/bigelile/IM002459.jpg
lurch
<ymg...@excite.com> wrote in message
news:c01932e6-116a-464d...@e1g2000pra.googlegroups.com...
You have shown the antenna and downstairs TV are good. Something you
bypassed with the 100' cable is bad. Add parts of the bad system, one at a
time, into the good system. Suspect ALL connectors and extension cables
until they work with the good system. The splitter is the main suspect as
all four down cables shouldn't fail at the same time. The inline amp may be
needed to overcome the loss of a 4-way splitter but you should see something
without it.
I hope the house wiring is RF and not fiber-optic!
RickMerrill
Ok. But you have to admit that putting that on an antenna signal will
send the db down the tubes.
Ron
No doubt. Won't work with cable either, at least not with my cable.
The former owner of my home was using that POS in the attic to split
the signal, and the picture on each TV was horrible. The cable company
installed a 6 way splitter/amp and that resolved the problem.
TKM
"lurch" <lu...@cox.net> wrote in message
news:49384904$0$5457$bbae...@news.suddenlink.net...
A similar problem in my home installation recently was traced to a broken
center pin in an RG-6 connector. When I stripped the cable to install the
connector, I nicked the copper center wire. When it was pushed into the
splitter, the pin broke and continuity was lost.
A continuity check is a good idea.
TKM
UCLAN
>> I just moved in to the new house. There is a 4-way coax splitter in
>> the attic, which has one input and four outputs (to different rooms).
>
> Every 4-way I have seen has actually been an amplifier - look at it
> from all sides and see if there is a power connection: it would probably
> be DC power from a 'wall-wart' located elsewhere.
http://www.pacificcable.com/Picture_Page.asp?DataName=200-204
http://www.pacificcable.com/Picture_Page.asp?DataName=200-214
http://www.pacificcable.com/Picture_Page.asp?DataName=200-224
http://www.pacificcable.com/Picture_Page.asp?DataName=201-284
http://www.pacificcable.com/Picture_Page.asp?DataName=201-104
http://www.pacificcable.com/Picture_Page.asp?DataName=201-204
http://www.pacificcable.com/Picture_Page.asp?DataName=201-224
http://www.pacificcable.com/Picture_Page.asp?DataName=201-264
http://www.pacificcable.com/Picture_Page.asp?DataName=201-274
http://www.pacificcable.com/Picture_Page.asp?DataName=201-234
http://www.pacificcable.com/Picture_Page.asp?DataName=201-244
All above are *unamplified* 4-way splitters.
http://www.pacificcable.com/Picture_Page.asp?DataName=200-700
A 4-output 3dB amplifier.
Even if his splitter is good, this amplifier may serve as a good substitute.
UCLAN
Sure, but since he already knows his 100' bypass from the antenna to the
TV works, adding just the lead from the antenna to the splitter would
quickly identify the culprit.
Ron
> RickMerrill wrote:
> >> I just moved in to the new house. There is a 4-way coax splitter in
> >> the attic, which has one input and four outputs (to different rooms).
>
> > Every 4-way I have seen has actually been an amplifier - look at it
> > from all sides and see if there is a power connection: it would probably
> > be DC power from a 'wall-wart' located elsewhere.
>
>
> All above are *unamplified* 4-way splitters.
>
> http://www.pacificcable.com/Picture_Page.asp?DataName=200-700
>
> A 4-output 3dB amplifier.
>
> Even if his splitter is good, this amplifier may serve as a good substitute.
Uh, he now knows that from about 12 hrs ago.
buffalobill
multimeter ohmmeter, small pocket or portable tv with rf to coax
adapters, some barrel connectors, some spare splitters. there's no way
to say where the open circuit or short might be without disconnecting
the branches of the octopus and one bad cable end or a terminating
screw-on resistor cap. if this is cable company wiring it may actually
belong to them. if the cable service is terminated, maybe it is cut at
the outside service box with a device, a ground, or a separation.
these may be on the wiring where you haven't looked yet.
GMAN
>On Dec 4, 12:49=A0pm, ymg...@excite.com wrote:
>> Hi,
>> I just moved in to the new house. There is a 4-way coax splitter in
>> the attic, which has one input and four outputs (to different rooms).
>> I know that previous owners had a cable (from the cable company). It
>> looks like the cable was going into the same splitter in the attic,
>> and then routed to rooms downstairs.
>> I want to use the TV antenna in the attic.
>> signal is getting to TVs downstairs. I also connected the antenna to
>> outcome - not even a change in a static when I plug in the antenna.
>> difference.
>> However, if I drop a 100' coax cable directly from the antenna in the
>> attic to the TV downstairs (bypassing the splitter and all of the home
>> cable wiring), the picture is crisp and perfect.
>> Can I run some tests to ensure cable continuation (from the attic to
>> rooms downstairs).
>> Does anybody know how I can get the signal from the antenna in the
>> attic to TVs downstairs?
>> Thank you.
>
>multimeter ohmmeter, small pocket or portable tv with rf to coax
>adapters, some barrel connectors, some spare splitters. there's no way
>to say where the open circuit or short might be without disconnecting
>the branches of the octopus and one bad cable end or a terminating
>screw-on resistor cap. if this is cable company wiring it may actually
>belong to them. if the cable service is terminated, maybe it is cut at
>the outside service box with a device, a ground, or a separation.
>these may be on the wiring where you haven't looked yet.
Any cable inside you home is yours....
Kenneth J. Harris
couple of things to look at. One possibility is that the splitter is
defective. Another is that the cable(or the connectors on the ends) from
the antenna to the splitter is defective. Try connecting the antenna to the
splitter with a different piece of cable, or with the 100 foot cable that
you know is good. If this gets the signal to your sets, then the cable was
the problem. If it still doesn't work, then I would say that the splitter
needs to be replaced.
Ken
TKM
"buffalobill" <wjoh...@roadrunner.com> wrote in message
news:8c5e89a3-94b0-4201...@r40g2000yqj.googlegroups.com...
Who knows if it's OK to measure the resistance (using a standard multimeter)
of a coax line connected to an amplified antenna after disconnecting the
amplifier power supply, but not the antenna. I'm concerned about damaging
the amplifier inside the antenna, but suspect an open line going from the
lightning arrestor up the roof to the antenna.
TKM
RickMerrill
> In article
> <c01932e6-116a-464d...@e1g2000pra.googlegroups.com>,
> ymg...@excite.com wrote:
>
>> I just moved in to the new house. There is a 4-way coax splitter in
>> the attic, which has one input and four outputs (to different rooms).
>> I know that previous owners had a cable (from the cable company). It
>> looks like the cable was going into the same splitter in the attic,
>> and then routed to rooms downstairs.
>> I want to use the TV antenna in the attic.
>> I tried connecting the TV antenna to splitter's input absolutely no
>> signal is getting to TVs downstairs. I also connected the antenna to
>> outcome - not even a change in a static when I plug in the antenna.
>> I bought a TV signal inline amplifier from RadioShack absolutely no
>> difference.
>> However, if I drop a 100' coax cable directly from the antenna in the
>> attic to the TV downstairs (bypassing the splitter and all of the home
>> cable wiring), the picture is crisp and perfect.
>> Can I run some tests to ensure cable continuation (from the attic to
>> rooms downstairs).
>> Does anybody know how I can get the signal from the antenna in the
>> attic to TVs downstairs?
>> Thank you.
>
> so try replacing it.
And old splitters were low freq. Replacing is a good idea.
Jeroni Paul
> also connected the antenna to
> each of splitter’s outputs (which go to TVs) – exactly the same
> outcome -
which discards the splitter as a possible culprit. It must be these
cables going downstairs.
On 6 Des, 05:20, Shawn Hirn <s...@comcast.net> wrote:
> My guess is the splitter is defective. Splitters are very inexpensive,
> so try replacing it.- Amaga el text entre cometes -
Kenneth J. Harris
the cables that goes downstairs and connected it to the cable from the
antenna. What he said could also be interpreted to mean that he
disconnected a cable from one of the splitter outputs and connected the
cable from the antenna to this output (which of course would do nothing).
Nothing surprises me anymore. Anyhow, I guess if all else fails he can
connect a known good cable from the antenna to a new splitter(plus amplifier
if needed) and run four new cables from the splitter down to his 4 tv's.
Not a terribly difficult job if you've done this sort of thing before.
"Jeroni Paul" <JERON...@terra.es> wrote in message
news:f1542a8f-1b5e-4c6a...@k8g2000yqn.googlegroups.com...
GMAN
>Why is everyone guessing the same? The poster said:
>
>> also connected the antenna to
>> outcome -
>
>which discards the splitter as a possible culprit. It must be these
>cables going downstairs.
>
>On 6 Des, 05:20, Shawn Hirn <s...@comcast.net> wrote:
>> My guess is the splitter is defective. Splitters are very inexpensive,
>> so try replacing it.- Amaga el text entre cometes -
Kenneth J. Harris
> Why would he hook the antenna to the splitters outputs?
My point exactly. His description of what he did could be interpreted that
way. A person with limited knowledge of cable connections could do that as
part of the process of trying every possible combo in order to get it to
work.
mm
>Hi,
>I just moved in to the new house. There is a 4-way coax splitter in
>the attic, which has one input and four outputs (to different rooms).
>I know that previous owners had a cable (from the cable company). It
>looks like the cable was going into the same splitter in the attic,
>and then routed to rooms downstairs.
>I want to use the TV antenna in the attic.
>I tried connecting the TV antenna to splitter's input – absolutely no
>signal is getting to TVs downstairs. I also connected the antenna to
>each of splitter’s outputs (which go to TVs) – exactly the same
>outcome - not even a change in a static when I plug in the antenna.
>I bought a TV signal inline amplifier from RadioShack – absolutely no
>difference.
>However, if I drop a 100' coax cable directly from the antenna in the
>attic to the TV downstairs (bypassing the splitter and all of the home
>cable wiring), the picture is crisp and perfect.
>Can I run some tests to ensure cable continuation (from the attic to
>rooms downstairs).
>Does anybody know how I can get the signal from the antenna in the
>attic to TVs downstairs?
>Thank you.
You can't run four tv's off of a non-amplified antenna. I'm surprised
they could run 4 tv's off of cable without putting in an amplifier
somewhere. I guess I'm wrong about that, but the cable signal is
stronger than a passive antenna signal. Get a radio shack tv signal
amplifier with one input and four outputs. You'll need to power it
with AC.
mm
You're absolutely right but I wouldn't call that an admission. I'd
call it an answer to the OP's problem.
mm
>
>
>You have shown the antenna and downstairs TV are good. Something you
>bypassed with the 100' cable is bad. Add parts of the bad system, one at a
>time, into the good system. Suspect ALL connectors and extension cables
>until they work with the good system. The splitter is the main suspect as
>all four down cables shouldn't fail at the same time.
You'd really have to work hard to make a passive splitter fail. I
guess applying 110 volts might do it.
> The inline amp may be
>needed to overcome the loss of a 4-way splitter but you should see something
>without it.
That might have been true in the old days, but with tv's going blank
if the signal is too weak, I wouldn't count on it.
mm
>
>Who knows if it's OK to measure the resistance (using a standard multimeter)
>of a coax line connected to an amplified antenna after disconnecting the
>amplifier power supply, but not the antenna. I'm concerned about damaging
>the amplifier inside the antenna,
You want to measure the resistance of the center conductor, right?
Easy to connect to the coax, but what do you want to connect to at the
other end? The rods that stick out of the antenna?
The voltage from a multimeter, 9 volts usually, isn't going to hurt
anything, but I don't think you can expect a meaningful measurement
either. There are semiconductors between the input and output of the
amplifier, and with no power, they might be acting as non-conductors.
Maybe I'm wrong about that, but how would you know if the resistance
is good or not, short of finding an identical antenna and measuring
it?
> but suspect an open line going from the
>lightning arrestor up the roof to the antenna.
So can't you disconnnect the cable at the antenna and measure the
resistance through the line with the arrestor only?
>TKM
>
Ron
Reread the post, he has an amp. Now granted, it's not a splitter/amp,
and that might make a difference, but there are ONLY two
possibilities.
Either the cable from the ant to the amp to the splitter is bad, or
the splitter is bad.
RickMerrill
As another poster said first, a 4-way unamplified splitter just will not
work with antenna, althought it will work with cable. This leads to a
solution for the OP: get an amplified splitter OR connect just 1 tv,
which I think they did.
Jeroni Paul
> As another poster said first, a 4-way unamplified splitter just will not
> work with antenna, althought it will work with cable. This leads to a
> solution for the OP: get an amplified splitter OR connect just 1 tv,
> which I think they did.
Even though it drops the signal by some dBs it still can work if the
antenna signal is good. It does for me, no amplifier required. Most of
the channels here come from the same repeater and are well equalized,
they remain strong enough for a snow free tuning after one or two
unamplified splitters.
GMAN
I agree it is preferable in his/her situation to get an amplifier but it is
just "NOT TRUE" that a non amplified 4 way wont work. I am doing just that.
My house has a four way splitter, I just placed a Yagi antenna on the roof, an
old school Radio Shack Model VU-90 XR to replace an older model.
http://www.radioshack.com/product/index.jsp?productId=2103085
I am running it down from the roof, with approx 35 feet of RG6U/Q quad
shield, into the built in house wiring from our 10 year old home. There is at
least a few hundred feet throughout our home and most likely its only RG59
cable to boot. And i get perfect analog and digital signals with this setup. I
DO plan on eventually replacing all the internal cable with RG6U/Q when i can
get aroung to it. And i do plan to add an amplifier to the system at that
time, but there is not one channel in Salt Lake City that i cannot get.
GMAN
>On Dec 8, 1:03=A0am, mm <NOPSAMmm2...@bigfoot.com> wrote:
>> On Thu, 4 Dec 2008 09:49:39 -0800 (PST), ymg...@excite.com wrote:
>> >Hi,
>> >I just moved in to the new house. There is a 4-way coax splitter in
>> >the attic, which has one input and four outputs (to different rooms).
>> >I know that previous owners had a cable (from the cable company). It
>> >looks like the cable was going into the same splitter in the attic,
>> >and then routed to rooms downstairs.
>> >I want to use the TV antenna in the attic.
>> >signal is getting to TVs downstairs. I also connected the antenna to
>> >outcome - not even a change in a static when I plug in the antenna.
>> >difference.
>> >However, if I drop a 100' coax cable directly from the antenna in the
>> >attic to the TV downstairs (bypassing the splitter and all of the home
>> >cable wiring), the picture is crisp and perfect.
>> >Can I run some tests to ensure cable continuation (from the attic to
>> >rooms downstairs).
>> >Does anybody know how I can get the signal from the antenna in the
>> >attic to TVs downstairs?
>> >Thank you.
>>
>> they could run 4 tv's off of cable without putting in an amplifier
>> stronger than a passive antenna signal. =A0 Get a radio shack tv signal
>> amplifier with one input and four outputs. =A0You'll need to power it
>> with AC.
>
>Reread the post, he has an amp. Now granted, it's not a splitter/amp,
>and that might make a difference, but there are ONLY two
>possibilities.
>
>Either the cable from the ant to the amp to the splitter is bad, or
>the splitter is bad.
Michael A. Terrell
The OP said there was an amplifier at the antenna. How is it
powered? If it is through the coax, the power inserter is missing, and
VERY FEW splitters for TV will pass power from one port to another.
Also, a lot are a single transistor preamp, and will pass a weak signal
without power. Usually 10 to 20 dB down from normal output. Add
another 7 dB loss from a four way splitter, and you can be down to the
noise floor.
--
http://improve-usenet.org/index.html
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There are two kinds of people on this earth:
The crazy, and the insane.
The first sign of insanity is denying that you're crazy.
Michael A. Terrell
RickMerrill wrote:
>
> As another poster said first, a 4-way unamplified splitter just will not
> work with antenna, althought it will work with cable.
A typical cable drop is + 10 dB at the tap where the home connectds to
the CATV system. A four way splitter adds a -7 dB loos, beinging the
signal to +3 dB, to cover the loss in the drop & distribution wiring.
If your OTA signals are +7 dB or higher, an unamplifed splitter works
just fine. If not, it can be anything from a little snow, to an
unuasble picture.
> This leads to a
> solution for the OP: get an amplified splitter OR connect just 1 tv,
> which I think they did.
RickMerrill
> RickMerrill wrote:
>> As another poster said first, a 4-way unamplified splitter just will not
>> work with antenna, althought it will work with cable.
>
> A typical cable drop is + 10 dB at the tap where the home connectds to
> the CATV system. A four way splitter adds a -7 dB loos, beinging the
> signal to +3 dB, to cover the loss in the drop & distribution wiring.
> If your OTA signals are +7 dB or higher, an unamplifed splitter works
> just fine. If not, it can be anything from a little snow, to an
> unuasble picture.
>
>> This leads to a
>> solution for the OP: get an amplified splitter OR connect just 1 tv,
>> which I think they did.
>
>
You're right, of course. I was in my country-mouse mode and not thinking
of the city-mouse who gets a much stronger signal!
Michael A. Terrell
mm wrote:
>
> On Thu, 4 Dec 2008 15:17:55 -0600, "lurch" <lu...@cox.net> wrote:
>
> >
> >
> >You have shown the antenna and downstairs TV are good. Something you
> >bypassed with the 100' cable is bad. Add parts of the bad system, one at a
> >time, into the good system. Suspect ALL connectors and extension cables
> >until they work with the good system. The splitter is the main suspect as
> >all four down cables shouldn't fail at the same time.
>
> You'd really have to work hard to make a passive splitter fail. I
> guess applying 110 volts might do it.
Lightning kills them by the millions. As an engineer for a major
CATV MSO years ago, I lost hundreds every month. They are simple three
port RF transformers, wound with wire the size of a human hair.
> > The inline amp may be
> >needed to overcome the loss of a 4-way splitter but you should see something
> >without it.
>
> That might have been true in the old days, but with tv's going blank
> if the signal is too weak, I wouldn't count on it.
>
> >I hope the house wiring is RF and not fiber-optic!
> >
Michael A. Terrell
mm wrote:
>
> On Fri, 05 Dec 2008 15:07:46 GMT, "TKM" <nom...@no.net> wrote:
>
> >
> >Who knows if it's OK to measure the resistance (using a standard multimeter)
> >of a coax line connected to an amplified antenna after disconnecting the
> >amplifier power supply, but not the antenna. I'm concerned about damaging
> >the amplifier inside the antenna,
>
> You want to measure the resistance of the center conductor, right?
>
> Easy to connect to the coax, but what do you want to connect to at the
> other end? The rods that stick out of the antenna?
>
> The voltage from a multimeter, 9 volts usually, isn't going to hurt
> anything, but I don't think you can expect a meaningful measurement
> either.
What kind of meter are you using with 9 V between the probes? Ohm
meters are usually current limited, or constant current sdesigns.
> There are semiconductors between the input and output of the
> amplifier, and with no power, they might be acting as non-conductors.
> Maybe I'm wrong about that, but how would you know if the resistance
> is good or not, short of finding an identical antenna and measuring
> it?
>
> > but suspect an open line going from the
> >lightning arrestor up the roof to the antenna.
>
> So can't you disconnnect the cable at the antenna and measure the
> resistance through the line with the arrestor only?
>
> >TKM
> >
UCLAN
>>Who knows if it's OK to measure the resistance (using a standard multimeter)
>>of a coax line connected to an amplified antenna after disconnecting the
>>amplifier power supply, but not the antenna. I'm concerned about damaging
>>the amplifier inside the antenna,
>
> You want to measure the resistance of the center conductor, right?
>
> Easy to connect to the coax, but what do you want to connect to at the
> other end? The rods that stick out of the antenna?
It's easy to test coaxial cable, no matter the length. Simply screw on a
75 ohm termination cap at one end, and measure from center conductor to the
ground shield at the other end. The ohmmeter will read 75 ohms plus whatever
the impedance of the cable is.
Geoffrey S. Mendelson
> It's easy to test coaxial cable, no matter the length. Simply screw on a
> 75 ohm termination cap at one end, and measure from center conductor to the
> ground shield at the other end. The ohmmeter will read 75 ohms plus whatever
> the impedance of the cable is.
Actually it won't. The impedance is at RF frequencies, the resistance is
at DC. The DC resistance of coax is close to 0, being the sum of the DC
resistance of the center conductor and the shield.
Resistance meters measure using DC or relatively low frequency AC, it
will be very close to 0.
Geoff.
--
Geoffrey S. Mendelson, Jerusalem, Israel g...@mendelson.com N3OWJ/4X1GM
Ron
Not with MY cable. That POS is what was in my current home when I
bought it and it was like watching TV in a blizzard.
mm
<mike.t...@earthlink.net> wrote:
>
>mm wrote:
>>
>> On Fri, 05 Dec 2008 15:07:46 GMT, "TKM" <nom...@no.net> wrote:
>>
>> >
>> >Who knows if it's OK to measure the resistance (using a standard multimeter)
>> >of a coax line connected to an amplified antenna after disconnecting the
>> >amplifier power supply, but not the antenna. I'm concerned about damaging
>> >the amplifier inside the antenna,
>>
>> You want to measure the resistance of the center conductor, right?
>>
>> Easy to connect to the coax, but what do you want to connect to at the
>> other end? The rods that stick out of the antenna?
>>
>> The voltage from a multimeter, 9 volts usually, isn't going to hurt
>> anything, but I don't think you can expect a meaningful measurement
>> either.
>
>
> What kind of meter are you using with 9 V between the probes?
Well it's been decades since I measured the voltage, if I ever did, so
let me just say that the voltage will be NO MORE THAN the 9 volt
battery provides. It might be less, but there are no voltage raising
circuits in a "standard multimeter", which the OP plans to use.
>Ohm
>meters are usually current limited, or constant current sdesigns.
How would knowing this help him? His concern was about damaging his
amplified antenna.
mm
<mike.t...@earthlink.net> wrote:
>
>mm wrote:
>>
>> On Thu, 4 Dec 2008 15:17:55 -0600, "lurch" <lu...@cox.net> wrote:
>>
>> >
>> >
>> >You have shown the antenna and downstairs TV are good. Something you
>> >bypassed with the 100' cable is bad. Add parts of the bad system, one at a
>> >time, into the good system. Suspect ALL connectors and extension cables
>> >until they work with the good system. The splitter is the main suspect as
>> >all four down cables shouldn't fail at the same time.
>>
>> You'd really have to work hard to make a passive splitter fail. I
>> guess applying 110 volts might do it.
>
>
> Lightning kills them by the millions. As an engineer for a major
>CATV MSO years ago, I lost hundreds every month. They are simple three
>port RF transformers, wound with wire the size of a human hair.
You're right. Oops.
Michael A. Terrell
mm wrote:
>
> On Mon, 08 Dec 2008 12:32:14 -0500, "Michael A. Terrell"
> <mike.t...@earthlink.net> wrote:
>
> >
> >mm wrote:
> >>
> >> On Fri, 05 Dec 2008 15:07:46 GMT, "TKM" <nom...@no.net> wrote:
> >>
> >> >
> >> >Who knows if it's OK to measure the resistance (using a standard multimeter)
> >> >of a coax line connected to an amplified antenna after disconnecting the
> >> >amplifier power supply, but not the antenna. I'm concerned about damaging
> >> >the amplifier inside the antenna,
> >>
> >> You want to measure the resistance of the center conductor, right?
> >>
> >> Easy to connect to the coax, but what do you want to connect to at the
> >> other end? The rods that stick out of the antenna?
> >>
> >> The voltage from a multimeter, 9 volts usually, isn't going to hurt
> >> anything, but I don't think you can expect a meaningful measurement
> >> either.
> >
> >
> > What kind of meter are you using with 9 V between the probes?
>
> Well it's been decades since I measured the voltage, if I ever did, so
> let me just say that the voltage will be NO MORE THAN the 9 volt
> battery provides. It might be less, but there are no voltage raising
> circuits in a "standard multimeter", which the OP plans to use.
>
> >Ohm
> >meters are usually current limited, or constant current sdesigns.
>
> How would knowing this help him? His concern was about damaging his
> amplified antenna.
My point was that the ohm meter was designed NOT to damage solid state
electronics, unless he is using a pre WW-II meter with a high test
voltage & current. A few old meters were still in shops when the first
transistor equipment hit the market. the service manuals warned you not
to use the outdated equipment, or you would destroy the transistors.
nobody >
Reword " plus the impedance of the cable is" to "plus the DC resistance
of the is" and you will be correct.
Measure the resistance of the terminator just in case, as I've seen some
that were 91 ohms....
If you see a run of cable that adds more than 10 ohms to the terminator
resistance, suspect a bad run of cable or corrosion at the connectors.
Just remember that DC continuity of coax is just that. Bad or lossy
cable can still show good continuity.
UCLAN
>>It's easy to test coaxial cable, no matter the length. Simply screw on a
>>75 ohm termination cap at one end, and measure from center conductor to the
>>ground shield at the other end. The ohmmeter will read 75 ohms plus whatever
>>the impedance of the cable is.
>
> Actually it won't. The impedance is at RF frequencies, the resistance is
> at DC. The DC resistance of coax is close to 0, being the sum of the DC
> resistance of the center conductor and the shield.
The OP's report of NO signal present is more indicative of an open rather
than a high impedance at some RF frequency
> Resistance meters measure using DC or relatively low frequency AC, it
> will be very close to 0.
Not with the 75 ohm terminating cap. It will be at least 75 ohms unless
there is a short somewhere in parallel with the 75 ohms.