Increasing Cable TV signal strength

[amdx]

On 2/8/2012 5:41 PM, Jeff Liebermann wrote:

On Wed, 08 Feb 2012 13:00:12 -0600, amdx<amdx@knology.net> wrote:

I'm on a boat, about 170ft from the utility post.

Ok, 200ft of coax. Presumably RG6a/u.

Recently our cable company switched to the wonderful world of
Digital TV.

You have been assimilated. Resistance is futile.

I got the new digital converter and had no picture.

Something is wrong. The nominal signal from the cable drop is suppose
to be 0dBm. If there's a splitter involved, they like to crank it up
to about 10dBm. Your 200ft of RG6a/u will drop the signal from
between 4dB at the low end, to about 6dB at the high end. Your set
top box is suppose to operate with a 10dB margin. If you would kindly
disclose the maker and model, it might be possible to find the specs.
Typically, you'll have at least 10dB margin. Even with 200ft of coax,
you should have 4 to 6dB margin.

Now remember the problem is quite intermittent, but seems to be
happening almost daily for short periods.

Drag your cable box and TV over to the splitter and try it on the
incoming drop. If that works, move to the ports on the splitter. Make
sure that the unused ports are terminated properly. If that doesn't
work, call your unfriendly cable company and ask them why they don't
have sufficient level to operate your set top box without the 200ft
cable. If it does work, find a 200ft RG6a/u cable that isn't
saturated with water. Try to get some compressing fittings instead of
the crappy crimp type.

There should be no water in the cable, it's only a couple of months
old and both ends have crimp on connectors and are located in a box or boat.

Your unspecified cable set top box may also have some user accessible
diagnostics which include per channel signal levels. You may want to
check those.

It does have diagnostics, I'm not sure if it is each channel though.
But I can get some info out of the box. I'll be there Friday and I'll
get that info and the model of the cable set top box.

I'm not familiar with Knology, but I suspect they do the same thing as
Comcast. With Comcast, the lower 72 channels are still analog in my
area. If so, you can probably plug your TV directly into the cable,
set the TV for cable frequencies, not broadcast, and see if that still
plays.

I'm using Comcast at the boat. We are lucky here (I think) in that

we have a choice of two cable companies.

Hint: Troubleshoot by substitution.

Drivel: I spent about an hour troubleshooting my TV distribution
system, only to find a brand new Type F "barrel" connector, with no
center connections. That which is most obviously correct, beyond any
need of checking, is usually the problem.
Drivel is good.

 

[amdx]

On 2/8/2012 6:38 PM, Jeff Liebermann wrote:

On Wed, 08 Feb 2012 15:41:08 -0800, Jeff Liebermann<jeffl@cruzio.com
wrote:

Your 200ft of RG6a/u will drop the signal from
between 4dB at the low end, to about 6dB at the high end.

Some better numbers for RG6a/u:
Freq Atten
MHz -dB
10 0.8
50 1.4
100 2.9
200 4.3
400 6.4
1000 11.0

The CATV band is approximately 50 to 800MHz. With 200ft of cable, you
should see 2.8 to 16dB of loss. While there may be problem at the
high channels, all the lower channels should work.

Any idea where channel 428 would be in that frequency range?
That's a duplicate of 4,2 but in HD, and it works when 42 doesn't.

The 4 way splitter has a loss of about -7dB.

Just a point. I may not have made it clear. I had the tech put in two
2way splitters and connect me to the first one. Hoping to gain 3db.
(or 4) and it did make a difference.

Picking a random set top box:
http://www.zoran.com/IMG/pdf/Simplify_NextGen_STBs_Solutions.pdf
See Page 3. Sensitivity is -18dBm for 256QAM and -24dBm 64QAM.

At the low end, you have 0dBm in, 7dB loss in the splitter, 2.8dB loss
in the coax, resulting in -9.8dBm to the box. That's much more than
the -18dBm/-24dBm needed.

However, at the high end, things are not so wonderful. 0dbm in, 7dB
loss in the splitter, and 16dB loss in the coax, which delivers
-23dBm. That's 1dB of margin, which is not very good. Still, it
should work on the lower channels.

 

[amdx]

On 2/8/2012 7:01 PM, Joerg wrote:

amdx wrote:
Hi All,
I'm on a boat, about 170ft from the utility post.
Recently our cable company switched to the wonderful world of
Digital TV. I got the new digital converter and had no picture.
I took the box back and got a second box, still no picture. So now I
suspect a weak signal and confirm that it is the cable length. The cable
company came out and gave me a better cable than I had installed. At
this point I have a picture but it is intermittent. The signal at the
utility post has 3 outputs and had a four way splitter, I suggested the
cable guy put in two 2 way splitters and give me the stronger (first) tap.
That got my signal to work almost all the time. I'd like to get the
signal to work 100% of the time.


Looks like the cable guys screwed up.

a. They should be putting enough signal on that cable to overcome the loss.

b. They should be able to measure the amplitude of pilot signals at your
end of the cable and tell you how much above minimums they are.


I don't has access to electricity at the utility post, so an amp is
out. Although I could try an amp at the cable box end. Is that reasonable?
I would run two cables if there was a way to make it increase signal
strength.
Getting anymore from the cable company is not an option.
Any ideas to get a better signal?
Mikek


PS.

When the signal fails it seems channel 41 is ok and above 42 it breaks up.
Curious to know if there is an unusual frequency jump between those two
digital channels.



If all else fails you may need an amp. What Fred means with drop amp is
usually called a "mast preamplifier", like this:

http://www.amazon.com/Uhf-Vhf-Antenna-Pre-Amp/dp/B0018CDGEQ/ref=sr_1_20?ie=UTF8&qid=1328748729&sr=8-20

I don't know this particular one but essentially it should be
weather-proof. It gets its DC voltage via the coax, from a wall wart
that would plug in at your boat. So no need to run a power supply cable
up there.

Don't go for too much gain. This dreaded DTV falls apart rather easily
on the slightest distortion or cross-modulation. Not sure if the above
amp can handle that. You might need a more expensive one. Michael
Terrell might know which ones are good. What matters is dynamic range.

Also, make sure you have a perfect 75ohms match at your end. The cable
box from the cable company should provide that. if you have Internet
and/or phone through them as well check that connection so it doesn't
cause reflections. On a boat at sea stuff can corrode quickly.

Oh, and don't dare to watch that boobs channel while your wife's on the
boat

Been trying to think of something funny to say about that...
Best I got is, she would say, "mine look better than those!

 

[Joerg]

amdx wrote:

On 2/8/2012 6:38 PM, Jeff Liebermann wrote:
On Wed, 08 Feb 2012 15:41:08 -0800, Jeff Liebermann<jeffl@cruzio.com
wrote:

Your 200ft of RG6a/u will drop the signal from
between 4dB at the low end, to about 6dB at the high end.

Some better numbers for RG6a/u:
Freq Atten
MHz -dB
10 0.8
50 1.4
100 2.9
200 4.3
400 6.4
1000 11.0

The CATV band is approximately 50 to 800MHz. With 200ft of cable, you
should see 2.8 to 16dB of loss. While there may be problem at the
high channels, all the lower channels should work.

Any idea where channel 428 would be in that frequency range?
That's a duplicate of 4,2 but in HD, and it works when 42 doesn't.

I believe that's entirely up to the cable company, you'd have to ask an
engineer there.

http://en.wikipedia.org/wiki/Digital_cable

Quote "For example, a cable company might call channel 5-1 "channel 732"
and channel 5-2 "channel 733"".

The 4 way splitter has a loss of about -7dB.

Just a point. I may not have made it clear. I had the tech put in two
2way splitters and connect me to the first one. Hoping to gain 3db.
(or 4) and it did make a difference.

Where does the other leg of that splitter go to? And is that end
properly terminated?

[...]

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Jeff Liebermann]

On Wed, 08 Feb 2012 19:24:06 -0600, amdx <amdx@knologynotthis.net>
wrote:

Now remember the problem is quite intermittent, but seems to be
happening almost daily for short periods.

Monitor the signal levels at the set top box and see if it coincides
with something nearby changing, such as the dock lights or operation
of heavy machinery. Maybe shove a DVM (digital voltmeter) into the AC
power and see if it moves around.

There should be no water in the cable, it's only a couple of months
old and both ends have crimp on connectors and are located in a box or boat.

I don't like crimp type connectors. Push on connectors are MUCH
better. Also, if the coax came from Radio Shack, all bets are off as
to the quality.

It does have diagnostics, I'm not sure if it is each channel though.
But I can get some info out of the box. I'll be there Friday and I'll
get that info and the model of the cable set top box.

Digital set top box diagnostics are different from analog. Instead of
per-channel levels, it might have levels for specific channels.

I'm using Comcast at the boat. We are lucky here (I think) in that
we have a choice of two cable companies.

If it's Comcast, you will probably still have the lower 72 channels
doing analog. Remove the set top box and plug in your TV directly.

Drivel is good.

The story of my life.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS

 

[Phil Hobbs]

amdx wrote:

On 2/8/2012 7:01 PM, Joerg wrote:
amdx wrote:
Hi All,
I'm on a boat, about 170ft from the utility post.
Recently our cable company switched to the wonderful world of
Digital TV. I got the new digital converter and had no picture.
I took the box back and got a second box, still no picture. So now I
suspect a weak signal and confirm that it is the cable length. The cable
company came out and gave me a better cable than I had installed. At
this point I have a picture but it is intermittent. The signal at the
utility post has 3 outputs and had a four way splitter, I suggested the
cable guy put in two 2 way splitters and give me the stronger (first) tap.
That got my signal to work almost all the time. I'd like to get the
signal to work 100% of the time.


Looks like the cable guys screwed up.

a. They should be putting enough signal on that cable to overcome the loss.

b. They should be able to measure the amplitude of pilot signals at your
end of the cable and tell you how much above minimums they are.


I don't has access to electricity at the utility post, so an amp is
out. Although I could try an amp at the cable box end. Is that reasonable?
I would run two cables if there was a way to make it increase signal
strength.
Getting anymore from the cable company is not an option.
Any ideas to get a better signal?
Mikek


PS.

When the signal fails it seems channel 41 is ok and above 42 it breaks up.
Curious to know if there is an unusual frequency jump between those two
digital channels.



If all else fails you may need an amp. What Fred means with drop amp is
usually called a "mast preamplifier", like this:

http://www.amazon.com/Uhf-Vhf-Antenna-Pre-Amp/dp/B0018CDGEQ/ref=sr_1_20?ie=UTF8&qid=1328748729&sr=8-20

I don't know this particular one but essentially it should be
weather-proof. It gets its DC voltage via the coax, from a wall wart
that would plug in at your boat. So no need to run a power supply cable
up there.

Don't go for too much gain. This dreaded DTV falls apart rather easily
on the slightest distortion or cross-modulation. Not sure if the above
amp can handle that. You might need a more expensive one. Michael
Terrell might know which ones are good. What matters is dynamic range.

Also, make sure you have a perfect 75ohms match at your end. The cable
box from the cable company should provide that. if you have Internet
and/or phone through them as well check that connection so it doesn't
cause reflections. On a boat at sea stuff can corrode quickly.

Oh, and don't dare to watch that boobs channel while your wife's on the
boat

Been trying to think of something funny to say about that...
Best I got is, she would say, "mine look better than those!

And you know what you'd better reply!

Cheers

Phil Hobbs

 

[Michael Coslo]

On 2/8/12 7:27 PM, Sal wrote:

"amdx"<amdx@knology.net> wrote in message
news:b7625$4f32c758$4b4c116f$23490@KNOLOGY.NET...
Hi All,
I'm on a boat, about 170ft from the utility post.
Recently our cable company switched to the wonderful world of
Digital TV.

snip

Getting anymore from the cable company is not an option.

I take respectful exception to that last sentence. My digital cable box is
about 130 cable-feet from the pole. My signal is tapped enroute for digital
telephone, tapped enroute for Internet and then split (by me) so I can feed
analog signals via a disttribution amp serving bedrooms, kitchen and shack.
I get enough from the pole tap to do the job.

I respectfully agree! 8^)

I don't know exactly how it's done now, but when I worked in the Cable
industry many moons ago, we had a lot of adjustment we could make. Even
more, we had variable by frequency attenuators so we could ensure that a
flat signal showed up. There was a lot of signal at the amplifiers, and
if we really needed more oomph, we could put in a distribution amp.
Another amp was really rare.

Somebody is treating you badly -- maybe the cable company, maybe the marina.
Yes, the approach for you to buy and install an inline, remote-power amp at
the pole is entirely valid, technically. However, that's not in keeping
with reasonable expectations. You needn't roll over so easily. It's
supposed to work.

What -- Are you worried you might offend somebody? That "somebody" seems
quite okay with kicking you in the ankle. Or elsewhere.

Yeah, there is something wrong there. For as much as people hate
Comcast, when I had cable internet put in, they replaced all the cable
from the pole to the house, and a lot inside the house. I did talk them
out of replacing the new cable I had put in, but insisted on putting new
connectors on them. The measured all the levels and set them high enough
that I'd be able to add more televisions if I liked.


Time to call the cable company and tell them you want your MTV.


- 73 de Mike N3LI -

 

[Mark]

Just a point. I may not have made it clear. I had the tech put in two
2way splitters and connect me to the first one. Hoping to gain 3db.
(or 4) and it did make a difference.

Where does the other leg of that splitter go to? And is that end
properly terminated?

[...]

--
Regards, Joerg

http://www.analogconsultants.com/

right good question...OP, when you had the analog signal, was there
significant ghosting?

digital boxes might tolerate a WEAK signal but they are intolerant of
reflections.

Mark

 

[Jeff Liebermann]

On Wed, 08 Feb 2012 19:30:07 -0600, amdx <amdx@knologynotthis.net>
wrote:

Any idea where channel 428 would be in that frequency range?
That's a duplicate of 4,2 but in HD, and it works when 42 doesn't.

Ummm... it's ugly. There are up to 10 standard definition or 2 HD
channels crammed into a 6 MHz wide RF slot. In order to untangle
this, you would need to run a PSIP decoder and extract the CVCT
record:
<http://en.wikipedia.org/wiki/PSIP>
to figure out where digital CH 428 fits. It could literally be
anywhere. However, if you happen to have an tuneable notch filter
(which I happen to have), you can stuff it in series with the cable,
and spin the dial until the signal disappears. Then, just read the
dial. (Comcast seems to be putting well paying and popular channels
on the lower frequencies, and obscure junk on the higher frequencies.
I'm not sure if this is intentional, accidental, or my imagination).

The 4 way splitter has a loss of about -7dB.

Just a point. I may not have made it clear. I had the tech put in two
2way splitters and connect me to the first one. Hoping to gain 3db.
(or 4) and it did make a difference.

Yeah, I saw that. I guess I wasn't too clear. The input signal can
vary over a 10-16dB range, and it still should work. The 3dB
difference between a two port and a 4 port splitter isn't going to
make much difference, exept at the higher channels.



--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS

 

[Sal]

"Michael Coslo" <mjc5@psu.edu> wrote in message
news:jgvb3o$jg4c$1@tr22n12.aset.psu.edu...

< snip >

Time to call the cable company and tell them you want your MTV.

No way to know from here, but they may not be able to add another amp.

While I was looking for something else, I lurched into this page:

<http://www.cisco.com/en/US/products/hw/cable/ps2217/products_white_paper0900aecd800fc94c.shtml>

While its intended audience is Internet modem designers, the noise
discussions are informative with regard to other signals, too.

My point: When you try stringing too many amps in line, the signal-to-noise
ratio (SNR) eventually becomes unacceptable. (Remember the acceptable SNRs
cited for 256 QAM and 64 QAM.)

"Sal"

 

[Sal]

"Sal" <sobars@aol.com> wrote in message news:jgvoub$fet$1@dont-email.me...

My point: When you try stringing too many amps in line, the
signal-to-noise ratio (SNR) eventually becomes unacceptable. (Remember
the acceptable SNRs cited for 256 QAM and 64 QAM.)

"Sal"

Sorry. I should have said carrier to noise ratio (CNR), not SNR. SNR
applies to post-detection signals. i joined the digital world late in life.

"Sal"

 

[Robert Baer]

amdx wrote:

Hi All,
I'm on a boat, about 170ft from the utility post.
Recently our cable company switched to the wonderful world of
Digital TV. I got the new digital converter and had no picture.
I took the box back and got a second box, still no picture. So now I
suspect a weak signal and confirm that it is the cable length. The cable
company came out and gave me a better cable than I had installed. At
this point I have a picture but it is intermittent. The signal at the
utility post has 3 outputs and had a four way splitter, I suggested the
cable guy put in two 2 way splitters and give me the stronger (first) tap.
That got my signal to work almost all the time. I'd like to get the
signal to work 100% of the time.
I don't has access to electricity at the utility post, so an amp is
out. Although I could try an amp at the cable box end. Is that reasonable?
I would run two cables if there was a way to make it increase signal
strength.
Getting anymore from the cable company is not an option.
Any ideas to get a better signal?
Mikek


PS.

When the signal fails it seems channel 41 is ok and above 42 it breaks up.
Curious to know if there is an unusual frequency jump between those two
digital channels.

Well, you could add an amplifier at the splitter where (nominally)

there is no power.
Use the coax center conductor for power; inline capacitors allow
signal to pass and feeding center via small choke allows DC but no signal.
Once upon a time there were little adapters that did this AC/DC thing...

 

[Ian Jackson]

In message <l916j7hrlnslf403b640ug9fkjk147i1go@4ax.com>, Jeff Liebermann
<jeffl@cruzio.com> writes

Something is wrong. The nominal signal from the cable drop is suppose
to be 0dBm. If there's a splitter involved, they like to crank it up
to about 10dBm.

Careful! Don't get your dBm mixed up with your dBmV. There's around 48dB
difference! 0dBm is a massive 48dBmV. That would certainly make most
set-top boxes wake up and pay attention!

--
Ian

 

[amdx]

On 2/8/2012 7:50 PM, Joerg wrote:

amdx wrote:
On 2/8/2012 6:38 PM, Jeff Liebermann wrote:
On Wed, 08 Feb 2012 15:41:08 -0800, Jeff Liebermann<jeffl@cruzio.com
wrote:

Your 200ft of RG6a/u will drop the signal from
between 4dB at the low end, to about 6dB at the high end.

Some better numbers for RG6a/u:
Freq Atten
MHz -dB
10 0.8
50 1.4
100 2.9
200 4.3
400 6.4
1000 11.0

The CATV band is approximately 50 to 800MHz. With 200ft of cable, you
should see 2.8 to 16dB of loss. While there may be problem at the
high channels, all the lower channels should work.

Any idea where channel 428 would be in that frequency range?
That's a duplicate of 4,2 but in HD, and it works when 42 doesn't.


I believe that's entirely up to the cable company, you'd have to ask an
engineer there.

http://en.wikipedia.org/wiki/Digital_cable

Quote "For example, a cable company might call channel 5-1 "channel 732"
and channel 5-2 "channel 733"".


The 4 way splitter has a loss of about -7dB.

Just a point. I may not have made it clear. I had the tech put in two
2way splitters and connect me to the first one. Hoping to gain 3db.
(or 4) and it did make a difference.


Where does the other leg of that splitter go to? And is that end
properly terminated?

[...]

They go to two other outlets, that are used for transient boaters.

sometimes they are used and sometimes they sit unterminated.
I have not seen my problem better or worse when boats are in or out.
But I have several 75 ohm F connector terminations. It's worth a try.
Mikek

 

[amdx]

On 2/8/2012 8:21 PM, Mark wrote:

Just a point. I may not have made it clear. I had the tech put in two
2way splitters and connect me to the first one. Hoping to gain 3db.
(or 4) and it did make a difference.

Where does the other leg of that splitter go to? And is that end
properly terminated?

[...]

--
Regards, Joerg

http://www.analogconsultants.com/

right good question...OP, when you had the analog signal, was there
significant ghosting?

digital boxes might tolerate a WEAK signal but they are intolerant of
reflections.

Mark

Never noticed any ghosting with the analog.
Mikek

 

[amdx]

On 2/8/2012 8:18 PM, Jeff Liebermann wrote:

On Wed, 08 Feb 2012 19:24:06 -0600, amdx<amdx@knologynotthis.net
wrote:

Now remember the problem is quite intermittent, but seems to be
happening almost daily for short periods.

Monitor the signal levels at the set top box and see if it coincides
with something nearby changing, such as the dock lights or operation
of heavy machinery. Maybe shove a DVM (digital voltmeter) into the AC
power and see if it moves around.

There should be no water in the cable, it's only a couple of months
old and both ends have crimp on connectors and are located in a box or boat.

I don't like crimp type connectors. Push on connectors are MUCH
better. Also, if the coax came from Radio Shack, all bets are off as
to the quality.

I'm sorry I got that wrong, they are F compression connectors.
Coax was from the cable company.

My drivel:

At my home, knology recently upgraded there system for faster internet.
A cableman said he heard me radiating a block away. he came in and
changed 7 crimp type connectors in my attic a couple of cable runs.
Speedtest.com went from 6 Mbps to over 11 Mbps with just those changes.

It does have diagnostics, I'm not sure if it is each channel though.
But I can get some info out of the box. I'll be there Friday and I'll
get that info and the model of the cable set top box.

Digital set top box diagnostics are different from analog. Instead of
per-channel levels, it might have levels for specific channels.

I'm using Comcast at the boat. We are lucky here (I think) in that
we have a choice of two cable companies.

If it's Comcast, you will probably still have the lower 72 channels
doing analog. Remove the set top box and plug in your TV directly.

Oh, if that is the fact, I may get me some browny points, If I can

get the signal up to snuff, then put the vcr back in the line, my wife
could record her soaps again.
That would get me 15 seconds of hero status!
Mikek

Drivel is good.

The story of my life.

 

[amdx]

On 2/9/2012 7:43 AM, amdx wrote:

On 2/8/2012 8:18 PM, Jeff Liebermann wrote:
On Wed, 08 Feb 2012 19:24:06 -0600, amdx<amdx@knologynotthis.net
wrote:

Now remember the problem is quite intermittent, but seems to be
happening almost daily for short periods.

Monitor the signal levels at the set top box and see if it coincides
with something nearby changing, such as the dock lights or operation
of heavy machinery. Maybe shove a DVM (digital voltmeter) into the AC
power and see if it moves around.

There should be no water in the cable, it's only a couple of months
old and both ends have crimp on connectors and are located in a box
or boat.

I don't like crimp type connectors. Push on connectors are MUCH
better. Also, if the coax came from Radio Shack, all bets are off as
to the quality.


I'm sorry I got that wrong, they are F compression connectors.
Coax was from the cable company.

My drivel:

At my home, knology recently upgraded there system for faster internet.
A cableman said he heard me radiating a block away. he came in and
changed 7 crimp type connectors in my attic a couple of cable runs.
Speedtest.com went from 6 Mbps to over 11 Mbps with just those changes.


It does have diagnostics, I'm not sure if it is each channel though.
But I can get some info out of the box. I'll be there Friday and I'll
get that info and the model of the cable set top box.

Digital set top box diagnostics are different from analog. Instead of
per-channel levels, it might have levels for specific channels.

I'm using Comcast at the boat. We are lucky here (I think) in that
we have a choice of two cable companies.

If it's Comcast, you will probably still have the lower 72 channels
doing analog. Remove the set top box and plug in your TV directly.

Oh, if that is the fact, I may get me some browny points, If I can get
the signal up to snuff, then put the vcr back in the line, my wife could
record her soaps again.
That would get me 15 seconds of hero status!
Mikek

Just an addition to the termination debate, the marina has about 150
taps, I'd be surprised if 30 of them are connected to a tv and the rest
are unterminated. The line generally goes to the utility pedestal into
a 2 way splitter and then about 1 ft of cable connects it to the 2 taps
for the boat owners.
Mikek

 

[Joerg]

amdx wrote:

On 2/8/2012 7:50 PM, Joerg wrote:
amdx wrote:
On 2/8/2012 6:38 PM, Jeff Liebermann wrote:
On Wed, 08 Feb 2012 15:41:08 -0800, Jeff Liebermann<jeffl@cruzio.com
wrote:

Your 200ft of RG6a/u will drop the signal from
between 4dB at the low end, to about 6dB at the high end.

Some better numbers for RG6a/u:
Freq Atten
MHz -dB
10 0.8
50 1.4
100 2.9
200 4.3
400 6.4
1000 11.0

The CATV band is approximately 50 to 800MHz. With 200ft of cable, you
should see 2.8 to 16dB of loss. While there may be problem at the
high channels, all the lower channels should work.

Any idea where channel 428 would be in that frequency range?
That's a duplicate of 4,2 but in HD, and it works when 42 doesn't.


I believe that's entirely up to the cable company, you'd have to ask an
engineer there.

http://en.wikipedia.org/wiki/Digital_cable

Quote "For example, a cable company might call channel 5-1 "channel 732"
and channel 5-2 "channel 733"".


The 4 way splitter has a loss of about -7dB.

Just a point. I may not have made it clear. I had the tech put in two
2way splitters and connect me to the first one. Hoping to gain 3db.
(or 4) and it did make a difference.


Where does the other leg of that splitter go to? And is that end
properly terminated?

[...]

They go to two other outlets, that are used for transient boaters.
sometimes they are used and sometimes they sit unterminated.
I have not seen my problem better or worse when boats are in or out.
But I have several 75 ohm F connector terminations. It's worth a try.

Yup, try it. Transient boaters will most likely not carry the required
set top box around but use the lower analog channels or nowadays maybe
UHF digital. Sort of "basic cable". Then the TV is connected directly
and those rarely have a true 75ohms input.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Jeff Liebermann]

On Thu, 09 Feb 2012 07:54:19 -0600, amdx <amdx@knologynotthis.net>
wrote:

My drivel:

At my home, knology recently upgraded there system for faster internet.
A cableman said he heard me radiating a block away. he came in and
changed 7 crimp type connectors in my attic a couple of cable runs.
Speedtest.com went from 6 Mbps to over 11 Mbps with just those changes.

Yep, that's the way it works. Compression type F connectors work
well. Crimp type are junk. The catch is that there are probably 100
different types of connectors, each with their own compression tools,
intended to fit about 8 different types of 75 ohm coax (RG6a/u,
RG59/u, single shielded, double shielded, quad shielded, direct
burial, etc). Mixing connector types and cables doesn't work. I got
fed up and "obtained" a 1000ft roll of double shielded RG6a/u, a big
of matching F, BNC, and phono connectors, a compression tool, a
stripping tool, and replaced all the junk cables in the house.

If it's Comcast, you will probably still have the lower 72 channels
doing analog. Remove the set top box and plug in your TV directly.

Oh, if that is the fact, I may get me some browny points, If I can get
the signal up to snuff, then put the vcr back in the line, my wife could
record her soaps again.
That would get me 15 seconds of hero status!
Mikek

I'm sure it's true for Comcast in Santa Cruz, CA. No clue on other
areas. The grand plan is to move all the analog channels to digital
area by area:
<http://www2.insidenova.com/news/2011/jun/22/comcast-removes-scores-channels-analog-cable-ar-1126652/>
<http://www2.newsadvance.com/business/2011/nov/09/comcast-switching-analog-digital-ar-1448489/>
Unfortunately, your area may be one of those that have moved to all
digital. Hard to tell from here.

Just an addition to the termination debate, the marina has about 150
taps, I'd be surprised if 30 of them are connected to a tv and the rest
are unterminated. The line generally goes to the utility pedestal into
a 2 way splitter and then about 1 ft of cable connects it to the 2 taps
for the boat owners.
Mikek

Can you determine if the marina is using a distribution amplifier
driving a big splitter, or is using a single cable trunk snaked
through the marina, with taps (directional couplers) at various
points? If taps, it's easy to install too many taps, or miscalculate
the tap type, resulting in level variations along the trunk.
<http://www.doityourself.com/forum/entertainment-center-tvs-stereos-vcrs-dvds-8-track-tape-players/334706-difference-between-tap-splitter.html>



--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Jeff Liebermann]

On Thu, 09 Feb 2012 09:01:21 -0800, Jeff Liebermann <jeffl@cruzio.com>
wrote:

How to Check Comcast Signal Levels
<http://www.ehow.com/how_7777024_check-comcast-signal-levels.html>
I'm not sure if this works on the newer set top boxes, but give it a
try.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558