# Cable TV booster

jake jot
My cable at ground floor has ok signal but in the second floor with about 20 meters additional cable. It has poor signal lately (because due to more resistance from old wiring). What kind of cable booster can actually boost the signal and can even eliminate the noise, rather than just boxes with no precise electronics inside?

Mentor
WITW? Are you talking about coax?

jake jot
WITW? Are you talking about coax?

Yes. Coax booster.

Staff Emeritus
rather than just boxes with no precise electronics inside

What? The? Heck?

These boxes all have electronics inside.

davenn, Wrichik Basu and berkeman
Mentor
Yes. Coax booster.
No. You absolutely do not need a booster to drive 20m of coax. Lordy.

Since this is between different floors, make sure that the receiving device is set to use the coax input instead of its wireless input.

jake jot
What? The? Heck?

These boxes all have electronics inside.

I have a word i forgot to use, so i just put "precise". The word is synonym to dependable, trustworthy, but there is this word to describe for example an engineer.

jake jot
No. You absolutely do not need a booster to drive 20m of coax. Lordy.

Since this is between different floors, make sure that the receiving device is set to use the coax input instead of its wireless input.

It is direct to coax input. But some channels have snows or lines. Replacing 20m of coax is expensive. Let's say there is corrosion halfway. What booster or amplier can theoretically work?

Mentor
It is direct to coax input. But some channels have snows or lines. Replacing 20m of coax is expensive. Let's say there is corrosion halfway. What booster or amplier can theoretically work?
This seems ludicrous to me. Go buy a 50m long quality RF coax cable, route it through your halls and through the stairs to join the two devices. When you see that it works, figure out a way to pull new cable through the walls. Lordy.

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The word is synonym to dependable, trustworthy, but there is this word to describe for example an engineer.
I think you are looking for "active" vs "passive". The active splitters require power and contain amplifiers while the passive ones just match the impedances.
To see if an amplifier might help, connect the second floor directly to the incoming cable (no splitting) and see if that helps. If so see if the splitter is defective by reversing the two output channels. If the direct connect works and the splitter not defective an active amplifier should help. Otherwise check the cable for bad.

jake jot
This is ludricous. Go buy a 50m long quality RF coax cable, route it through your halls and through the stairs to join the two devices. When you see that it works, figure out a way to pull new cable through the walls. Lordy.

I put the 20 meters outside the house exposed to sun and rain. How could it degrade the signal when there is a rubber cover to the coax?

What is the highest quality coax cable in the planet? Because with Covid everywhere id need to order online so i can't examine it.

What kind of cable booster can actually boost the signal and can even eliminate the noise, rather than just boxes with no precise electronics inside?
To boost a signal requires an active electronic amplifier, with a power supply. A distribution box may only need passive electronics to match the impedance of the cables.

If you have a problem with distribution, it is probably due to connectors, not to cables. There is no advantage in using a booster to overcome cable damage or poor connections. Check all the connectors first. If that does not fix the problem, run a temporary cable to prove the old cable is faulty. Replace a faulty cable.

jake jot
I think you are looking for "active" vs "passive". The active splitters require power and contain amplifiers while the passive ones just match the impedances.
To see if an amplifier might help, connect the second floor directly to the incoming cable (no splitting) and see if that helps. If so see if the splitter is defective by reversing the two output channels. If the direct connect works and the splitter not defective an active amplifier should help. Otherwise check the cable for bad.

I tested it. The splitter not defective and the direct connect works but with noises just the same. What is the best active amplfier since i will order online and can't examine it. Also i thought amplifier is useless for 20 meters coax as someone else mentioned. Pls clarify guys. Thanks.

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You need new cable. Keep it out of direct sun if possible. Just go to a quality supplier it will be fine. I think my cable company will do it for me for pretty cheap...COVID 19 would be the issue.

jake jot
This is my cable..is it RG 6? I can't find whether it is at google.

Amphenol CTFC-T10 B ShieldX TCTSFx77-LTU

This is the image in the tv channel watched by my niece. But the other channels seem to be fine.

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It is odd that it is only one channel. Do you have a cable company?

jake jot
It is odd that it is only one channel. Do you have a cable company?

Yes. Most of the other 30 channels are ok. It is the babytv channel with problem. But my main tv at ground floor has no problem in the babytv. So its really the extension..anyway here is the signal info at babytv

The cartoon network channel is ok and has this spec

Where the loss of signal quality is only on one channel frequency, the problem is often related to the length of the cable, between a poor connection with an impedance mismatch, and the receiver. For digital TV, all channels on the one frequency bearer can be expected to have poor quality.
We need to know how your cable system distributes the channels on different frequencies.

jake jot
Where the loss of signal quality is only on one channel frequency, the problem is often related to the length of the cable, between a poor connection with an impedance mismatch, and the receiver. For digital TV, all channels on the one frequency bearer can be expected to have poor quality.
We need to know how your cable system distributes the channels on different frequencies.

I don't know how the cable system distributes it but remember our primary tv at ground floor has good babytv signal. In the second floor, the problem only started this week. It was ok a week ago. Its not loose connections. And its difficult to rewire cable. So i want first to get a coax booster just to try what happened and test the theory booster is useless for 20 meter with corroded part. If still noises at screen then ill change the cable. So what kind of coax amplifier to get. Are there many kinds?

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jake jot

With covid, i just can't let any technician come into the house especially when it is just the cable that is the problem.

I'll do it conventionally. I'll first replace the coax plugs. If doesn't solve it. I'll replace the cable.

Do you know what can cause the following artifact? Is it the ground shorting to the middle wire, or resistance caused by corrosion in wire? Or loose connection? Since there is degradation of signal. Theoretically why won't a signal amplifier fix it?

Btw.. what is the arfifact called so I can google it? Aliasing? Video noises? Manifold defect? Topological anomaly? What?

Pixelation.
Each rectangular part of the image is painted as it changes. If data is missing a patch cannot be painted and so previous image gets left there. It shows that some blocks of received data have been damaged beyond correction, and so are lost.

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With covid, i just can't let any technician come into the house especially when it is just the cable that is the problem.
Can you let the cable people do the outside work and supply the cable? You do the inside work and let them know these rules before they show up (in masks and gloves). I am with you 100% about COVID protection but masking with N95 and careful activity works. At least see if they will supply the cable (maybe you pick it up)
I haven't been indoors with non-bubble people since April.

jake jot
Can you let the cable people do the outside work and supply the cable? You do the inside work and let them know these rules before they show up (in masks and gloves). I am with you 100% about COVID protection but masking with N95 and careful activity works. At least see if they will supply the cable (maybe you pick it up)
I haven't been indoors with non-bubble people since April.

If it's fibre optics cable, I may ask them to come. But not 20 meter coax cable which is easy to connect. Not worth the risk with the more contagious UK Covid strain all over the world now.

So coax cable need certain bandwidth in the conductor? And if not enough size or diminish by corrosion, it can cause pixelation? In electricity, there is a formula for current and capacity. What is the formula for coax cable and information capacity?

Gold Member
Amphenol is one of the top coax suppliers, stick with them if you can.
The Amphenol Global Search page, below, that has several entries that my old computer can not talk to is VERY slow to respond. Hopefully you can get more information from them.

INSERT: Just found TFC-10;
created by(?): Times Fiber Communications http://www.timesfiber.com

The cable you have is 75 Ohm and has a shield layer that is extruded Aluminum, not foil like the indoor ones most folks are used to. As such it is probably a little more sensitive to repeated bending. If outdoors (as it is designed for) it probably should be restrained from flapping in the wind, repeated bending may eventually crack the shield, causing signal loss. (the flapping and bending is speculation on my part, based on the descriptions on the manufacturers website)

One site says you can directly connect RG6 to the TFC-T10 with an 'F' male-male connector. Since they are both 75 Ohm you should be good to go.

The amplifier you are looking for would be an "Antenna Booster" or a "Distribution Amplifier." Both require power and actually amplify the signal. If you see some that advertise improvement but do NOT require power, they are probably lying.

The Antenna Booster would be the lower cost option and would likely help/hide the problem.

Distribution Amplifiers come in a wide range of capabilities and costs, from \$$to \$$\\\$.

Cheers,
Tom

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sysprog
jake jot

I replaced the f connector or plug and there is still pixellation (its not the isolator because i bypassed it), in fact worse. So ill replace the whole 20 meter coax cable. Ok what is better than RG6? I won't get TFC-T10 anymore bec its more fragile. Or better yet since its only 20 meter coax. Ill get milspec coax. What kinds of coax do milspec facilities like nuclear power plant or NORAD use?

(I noticed that with the isolator, the pixellation is worse. I couldn't find any schematic of the isolator. Is there something like isolation transformer inside? Is the current stop from flowing and coupling via magnetic field, how does it work?

Also i tried to insert the center wire only. The cable tv has no signal. I read the wire shielding in the outer part of the cable is to prevent noise. In my case, it is used as ground or return signal? If 50% is broken, how would the shielding affect the center wire RF transmission?)

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jake jot
No. You absolutely do not need a booster to drive 20m of coax. Lordy.

Since this is between different floors, make sure that the receiving device is set to use the coax input instead of its wireless input.

The plot (or wire) thickens. I found out the 70 meter coax cable from street to inside apartment is RG-59 (its written on the wire). It can't be pulled and replaced.

Right after it is the splitter where the right wire goes to TV (only 1 meter), while the left wire goes 20 meters to the 2nd floor (using TCF-T10 wires as Tom G. showed)

So coax amplifier is really required now before the splitter, is it not? I'll just replace the defective 20 meters with RG6 because even with Milspec golden wires, the RG-59 is the limiting factor.

What is best coax amplifier in the world? I only have one chance to buy it at amazon and won't replace it for a long time so don't want to make any mistakes. Thanks.

What is best coax amplifier in the world?
You really should not need an amplifier.

The best coax cable and the best amplifier will not fix the problem.

Swap over the TV sets. Does the problem move with the TV ?
Swap over the two connections to the splitter. Test again.
Shake the cables, does it cause problems?
Check the 20 metre coaxial cable for a crush, nail, screw, or vermin damage.
Replace the 20 metre coaxial cable with RG59 if necessary.

jake jot
You really should not need an amplifier.

The best coax cable and the best amplifier will not fix the problem.

Swap over the TV sets. Does the problem move with the TV ?
Swap over the two connections to the splitter. Test again.
Shake the cables, does it cause problems?
Check the 20 metre coaxial cable for a crush, nail, screw, or vermin damage.
Replace the 20 metre coaxial cable with RG59 if necessary.

Remember there are 70 meters of RG59 before the 20 meters of TFC-T10. So total is 90 meters. 90 meters is not horrors length and can do without coax amplifier?

Gold Member
So... have you gotten around to switching the TV's, yet ? (both of them, not just the one).

jake jot
So... have you gotten around to switching the TV's, yet ? (both of them, not just the one).

My tvs are 55" 4K Hdtv hanged in walls. Its so heavy to carry in between floors. Its like this.

https://www.lg.com/levant_en/tvs/lg-55UM7660PVA#none

I have changed and switched the splitter too. Later ill try decades old RG-59 wires (removed from house put by previous tenants) kept in boxes in the attic to see if the pixellation would be gone.

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jake jot
My tvs are 55" 4K Hdtv hanged in walls. Its so heavy to carry in between floors. Its like this.

https://www.lg.com/levant_en/tvs/lg-55UM7660PVA#none

View attachment 276372

I have changed and switched the splitter too. Later ill try decades old RG-59 wires (removed from house put by previous tenants) kept in boxes in the attic to see if the pixellation would be gone.

Here is some old RG59 coax. Need to get adaptors to connect them and test. I wonder if there are wireless coax transmitter/receivers? Whats the bandwidth of cable tv with 100 channels? Like wifi?

Gold Member
Coming in late here but in my arrogance I think I can add a bit. HFAC connections are tricky. The key quality at the TV is signal/noise since most devices (I believe) have some amount of amplification and AGC.

Since you say the situation became worse i.e. something changed that suggest one of two possibilities. Reduced signal or increased noise. Here's my checklist on possible causes (anyone chime in if I missed something).

Possible sources of noise are:
• Noise in the original signal from the provider.
• Noise occurring at connections due to non-linear behavior (oxide coatings on connectors can cause them to behave differently.. the most extreme case being a spark gap which conducts only after voltage rises above a threshold.)
• Noise from external EMF leaking in at connectors.
• Noise from other devices connected to the circuit.
• Noise from external EMF leaking directly into the cable. (They're shielded but kinks or wear can defeat shielding.)
Possible sources of signal level loss are:
• Reduced signal from the provider.
• Degredation of the cables (unlikely, even with cheap cables) [Edit: that is unless... I've seen old cables where water seeped in through cuts in insulation or at connectors and oxidized the shielding. They looked fine until the insulation was stripped off. Look for cuts or connections exposed to moisture/weather.]
• Signal attenuation at connectors.
• Signal leaking out at connectors.
• Line reflections at connectors.
• Line reflection along cables (at kinks or damaged areas).
• Diffractive interference due to change of cable geometry. (Can be very frequency specific, signal at one frequency creates a standing wave and your TV happens to be at a node.)
• Signal loss at other devices connected to the circuit.
I think I've covered most bases. If I were the OP I would first try to remember exactly when the trouble started and query (very politely and non-confrontationally) other residents to see if they have added or upgraded any devices connected to the cable system. This could have added noise, reduced signal, or (less likely but conceivable) caused an odd standing wave issue. The former could be solved by having a filter or attenuator placed on the new device which doesn't affect its performance but removes the problem. I would first try to eliminate other issues.

The less likely but possible geometric issues may possibly be resolved by changing the length of cable to the problematic TV. Try adding a 6ft extension and see if the reception improves. (very unlikely but would be definitive.) Alternatively if you have enough extra cable, cutting of a bit and adding a new connector.

My first course of action would be to inspect the entire run of cable or as much as possible. There may be kinks that over became pronunced enough as the plastic dielectric deformed to cause the problem, or there may be wear spots or cuts at some point where the cable was mounted.

I would next check each connection for oxidation. Try lightly sanding and tinning copper axial connector with a bit of silver solder. Be sure to clean off all flux afterwards.

You could then try to eliminate any incomming noise from connectors. Simply wrap them in aluminum (or aluminium for you non 'mericans) foil one at a time and checking to see if the problem goes away.

Note that if the problem is comming from beyond your apartment then a booster may just boost the noise as well as signal. If the problem is also not from your provider a booster at the main connection may solve it.

Some noise can be harmonics of a different frequency signal leaking into the system and could be eliminated with a band pass filter. Something like that could be comming from a device in your appartment so also try to correlate any new equipment with the timing of the problem's onset.

Other than these you could speak with the provider and see if they could boost or have recently decreased your signal. (I believe they try to keep the signal strengths "just enough" plus a margin to save on power and equipment degredation.) You could also ask them if you could speak directly with one of their technicians who could give you some more direct advice based on their experience.

Hmm... what else? It could be gremlins or other supernatural entities. Get a good mystic for that one. I can't help you.

Final note: My expertise is theoretical physics and not cable tech. I'm thinking in general terms and have no real experience to weigh the probabilities of these various cases. I hope my late post has not been too redundant from earlier advice and proves helpful in some way.

Whats the bandwidth of cable tv with 100 channels?
A maximum of about 700 MHz. RG59 has more than sufficient bandwidth. There is no sharp cutoff with coax cable.
If I were the OP I would first try to remember exactly when the trouble started and query (very politely and non-confrontationally) other residents to see if they have added or upgraded any devices connected to the cable system.
It may be that one of the neighbours has plugged in a booster amplifier, that is being overdriven and oscillating, causing the pixelation on the problem channel.

jake jot
Coming in late here but in my arrogance I think I can add a bit. HFAC connections are tricky. The key quality at the TV is signal/noise since most devices (I believe) have some amount of amplification and AGC.

Since you say the situation became worse i.e. something changed that suggest one of two possibilities. Reduced signal or increased noise. Here's my checklist on possible causes (anyone chime in if I missed something).

Possible sources of noise are:
• Noise in the original signal from the provider.
• Noise occurring at connections due to non-linear behavior (oxide coatings on connectors can cause them to behave differently.. the most extreme case being a spark gap which conducts only after voltage rises above a threshold.)
• Noise from external EMF leaking in at connectors.
• Noise from other devices connected to the circuit.
• Noise from external EMF leaking directly into the cable. (They're shielded but kinks or wear can defeat shielding.)
Possible sources of signal level loss are:
• Reduced signal from the provider.
• Degredation of the cables (unlikely, even with cheap cables) [Edit: that is unless... I've seen old cables where water seeped in through cuts in insulation or at connectors and oxidized the shielding. They looked fine until the insulation was stripped off. Look for cuts or connections exposed to moisture/weather.]
• Signal attenuation at connectors.
• Signal leaking out at connectors.
• Line reflections at connectors.
• Line reflection along cables (at kinks or damaged areas).
• Diffractive interference due to change of cable geometry. (Can be very frequency specific, signal at one frequency creates a standing wave and your TV happens to be at a node.)
• Signal loss at other devices connected to the circuit.
I think I've covered most bases. If I were the OP I would first try to remember exactly when the trouble started and query (very politely and non-confrontationally) other residents to see if they have added or upgraded any devices connected to the cable system. This could have added noise, reduced signal, or (less likely but conceivable) caused an odd standing wave issue. The former could be solved by having a filter or attenuator placed on the new device which doesn't affect its performance but removes the problem. I would first try to eliminate other issues.

The less likely but possible geometric issues may possibly be resolved by changing the length of cable to the problematic TV. Try adding a 6ft extension and see if the reception improves. (very unlikely but would be definitive.) Alternatively if you have enough extra cable, cutting of a bit and adding a new connector.

My first course of action would be to inspect the entire run of cable or as much as possible. There may be kinks that over became pronunced enough as the plastic dielectric deformed to cause the problem, or there may be wear spots or cuts at some point where the cable was mounted.

I would next check each connection for oxidation. Try lightly sanding and tinning copper axial connector with a bit of silver solder. Be sure to clean off all flux afterwards.

You could then try to eliminate any incomming noise from connectors. Simply wrap them in aluminum (or aluminium for you non 'mericans) foil one at a time and checking to see if the problem goes away.

Note that if the problem is comming from beyond your apartment then a booster may just boost the noise as well as signal. If the problem is also not from your provider a booster at the main connection may solve it.

Some noise can be harmonics of a different frequency signal leaking into the system and could be eliminated with a band pass filter. Something like that could be comming from a device in your appartment so also try to correlate any new equipment with the timing of the problem's onset.

Other than these you could speak with the provider and see if they could boost or have recently decreased your signal. (I believe they try to keep the signal strengths "just enough" plus a margin to save on power and equipment degredation.) You could also ask them if you could speak directly with one of their technicians who could give you some more direct advice based on their experience.

Hmm... what else? It could be gremlins or other supernatural entities. Get a good mystic for that one. I can't help you.

Final note: My expertise is theoretical physics and not cable tech. I'm thinking in general terms and have no real experience to weigh the probabilities of these various cases. I hope my late post has not been too redundant from earlier advice and proves helpful in some way.

Thanks for your incredible insights. I am guessing the problem is the cooper at center. I kept bending them over the years i think it has already some bending fracture. Also with the grounding external braids of the coax. I wonder if is just used for grounding or return signals. When i just inserted the cooper. There was no signal and even with some fine ground braids connecting it to f connector. Anyway ill just replace the whole 20 meter cable with RG6. I think it should solve it. Many thanks guys for the assistance. I need to know though how exactly the isolator work inside (in my earlier message to Tom G).

Gold Member
(I noticed that with the isolator, the pixellation is worse. I couldn't find any schematic of the isolator. Is there something like isolation transformer inside? Is the current stop from flowing and coupling via magnetic field, how does it work?
I do not know, I have never had one apart. If you find out, please let us know.
Try adding a 6ft extension and see if the reception improves. (very unlikely but would be definitive.)
At 450MHz the wavelength is about 53cm in the coax. For standing wave cancellation, the test length to add or subtract would be either 1/4 wavelength (around 13cm) or 1/2 wavelength (around 26.5cm).

Since only one TV channel is affected, there is either weak signal coming in, outside interference, or cable/connector damage in two or more spots at either 1/4 or 1/2 wavelengths apart. Or unlikely, a bad TV set.

@jake jot, maybe you can borrow a small TV from a friend, relative, or neighbor so you can test. That might be easier than replacing the coax.

In post #31 above, the photo shows that the black coax is heavily damaged; do not bother trying to use that one!

Cheers,
Tom