Reception Problems
 

I'd like some advice about potential solutions to weak or intermittent TV reception. I have a standard multi-band rooftop antenna (about 10 years old) pointed south to southeast, supposedly the direction of most of the broadcasters in the area. I have messed with the direction somewhat with no signal improvement. The antenna is connected to some kind of amp that is then split into cables going throughout the house to two TVs and an empty jack.

According to the chart below, i should have great reception. I never had a complaint about the analog signal but have experienced intermittent lost signals and pixelation in the digital era. The typical signal at the TVs are 25 to 32 db with the amp and 22 or less (no signal) without the amp. I was thinking of trying a new antenna but am not convinced this would help. However, I am open to suggestions before i call the cable company.

http://www.tvfool.com/?option=com_wr...21930b794fcc85

Which of these two antennas looks most like yours?

VHF/FM

UHF/VHF

Have you tried removing the amplifier completely? The signal levels in your area are strong enough to advise against any amplifier. Certainly when only two sets are connected.

Have you inspected the antenna for corrosion and other wear?

TV Antennas and Reception
 

The Tv stations transmissions at your location are Very Strong. So there is problems with the distribution system. Check ALL Connections , look inside the connectors on the ends of the coax and see if the outer foil shield / shield wires are pushed in toward the center conductor wire , the center conductor wire is wire that carries the signal. Also look and see if metal shavings/flakes are on the foam that is in between the center wire and the outer metal foil shield and shield wires. I recommend removing ALL amplifiers parts , the power supply , any power injectors , any and all amplifiers. I recommend connecting a known to be good coax from a known to be good matching transformer at the antenna and a known to be good antenna - connected direct to one Tv. Point the outside Tv antenna at about 150 degrees magnetic compass , here is how to point Tv antennas , http://www.kyes.com/antenna/pointing/pointing.html . Only use a 2 way splitter for the two Tv's in the house , do not use a 3 way splitter , 4 way splitter or more splitters , every time a split takes place the signal is reduced.

My antenna looks like the UHF/VHF antenna.

Barely any usable signal to the TV at all without the amp. The typical signal at the TVs are 25 to 32 db with the amp and 22 or less (no signal) without the amp.

The antenna looks fine physically. It has the usual oxidation you'd expect for something aluminum sitting out in the elements for 10 years.

TV Antennas and Reception
 

To Prove that Digital Broadcast Tv Transmissions are Strong at your location , use one of these NON Amplified indoor Tv antennas connected to one Tv , http://forum.tvfool.com/showthread.php?t=233 . Here is how to point indoor Tv antennas , http://www.kyes.com/antenna/pointing/pointing.html . radio shack also has a simple NON Amplified indoor tv antenna , catalog number 15-1874

John,
What is the matching transformer and what does it do?

TV Antennas and Reception
 

A matching transformer connects the coax to the outside roof top type Tv antenna. It matches the 300 ohm connection points of the tv antenna to the 75 ohm coax. The radio shack catalog number 15-1230 is a typical matching transformer

TV Antennas and Reception
 

Read and understand about , REAL Digital Broadcast Tv Channels , Virtual Digital Broadcast Tv Channels , Analog Broadcast Tv Channels , http://forum.tvfool.com/showthread.php?t=695

This Manual illustrates the location of, and how to connect the matching transformer. Notice the illustration at the end of step 3. If you find that you can not loosen the hardware to disconnect the matching transformer wires from the lead in terminals (illustrated at the end of step 1), you should consider replacing the antenna.

If water has entered the coax cable, it needs to be replaced.

Thanks John. Since it seems that you do not think that the antenna itself is the problem, this transformer and the cabling to and from it are the first place to investigate. I have already tested the distribution system with and without the amp and its cabling and the results were the same for both TVs. I doubt that the cabling to both TVs have failed in the same way at the same time; so, I will not rewire the house unless I am convinced it is necessary.

The most likely components to fail will be in the weather.

Thanks GUM. There is some kind of black box attached to the mast that must be the transformer as coax cable from the house enters and the two wire cable exits and is attached to the antenna. I'll mess with that first and see what happens. Looks like the least expensive option for swapping out parts.

That sounds like the actual amplifier. - Example -The indoor power supply and power insertion block is often mistaken for the amplifier. You may find that once ALL the amplifier components are removed your reception may dramatically improve... here's hoping anyway...

http://forum.tvfool.com/attachment.p...1&d=1306904952

There are some older matching transformers that could look like that though.

TV Antennas and Reception
 

I am not suggesting replacing all of the cable in the house. If the outdoor antenna has a black box as part of the antenna , and the coax is connected to it then the antenna may have a built in/on matching transformer and that matching transformer may be bad. A good matching transformer and a long length of cable connected to one Tv will show that the reception of the antenna is good. And the long length of coax can be used to trouble shoot the distribution system by connecting at different points of the distribution system so as to find the part of the system that needs to be fixed.

TV Antennas and Reception
 

Here is a example picture and information , terminal board/matching transformer that snaps into place on the underside of the antenna . Winegard CB 1469 . http://winegarddirect.com

GUM, This picture you embedded looks exactly like the setup I have. I guess this pre-amp is also the transformer because coax cable goes into the black box from the house but the two-wire cable comes out of the box to the antenna connections. Then there is another powered box inside the house that receives the coax from the black box. It is distributed from there to the TVs thru additional coax cable.

There are several variations of this concept... Generally, the part(s) inside the building are power related, and are designed to send power up to the mast mounted amplifier unit.

The mast mounted unit may have one or two inputs. If two, one is usually for VHF and the other for UHF. There can be any combination of 300 ohm twin-lead or 75 ohm coax input and output. It sounds like you may have a short section of 300 ohm twin-lead from the antenna to the amplifier and the output is 75 ohm coax.

I would be very curious to know how your system performs when you remove the amp and power supply. If there is a short section of twin-lead between the antenna and amp now, a matching transformer will be needed.

Ok, my next experiment will be to remove both the outdoor pre-amp/transformer piece and the indoor power supply piece. Previously, I experimented by removing just the power supply piece on the inside of the house and the signal was much worse. I will report on the outcome.

I finally went up on the roof again and into the attic to satisfy our curiosity. Similar to the diagram that you provided: THere was a transformer right at the antenna contacts; this was connected to a coax cable hooked on the other end to another transformer that went in the opposite direction into the pre-amp/transformer (evidently the pre-amp/transformer two wire cable was not long enough to reach the antenna contacts); then the cable from the pre-amp/transformer went into a powered box inside the attic; the signal from the powered box went to a four way splitter that had cabling to the two TV's and an unused jack.

So, I disconnected everything as directed. I bought a new transformer at the Shack and hooked it directly to the antenna contacts. The cable from the new transformer goes directly to the 4-way splitter in the attic now.

The results are that my reception and signals at the TVs are pretty much the way they were before with the pre-amp, which is kind of interesting. I guess the pre-amp was not doing a whole lot. I repositioned the antenna while I was up there and most stations are acceptable at around 30db. The worst stations are local channel 2 (24 db) and local channels 39-1, 39-2 (variable at 12-18db); so the latter fades repeatedly.

Another hardware item I noted is that one of the long horizontal spokes on the side of the antenna facing away from the transmitters is missing. I am not sure how big an impact this has as it is a fairly large antenna.

I presume you are referring to KPRC (NBC, real channel 35, virtual channel 2.X) and KIAH (CW, real channel 38, virtual channel 39.X).

Is reception of KIAH stable or does it break-up?

Can you afford to buy a 'test' cable? I would be curious to know how the system performs when you connect the antenna to only the TV you are using as your signal meter. The goal is to determine with some certainty, the quality of the signal from the antenna and to remove (while testing) the possible problems in your distribution network.

Are all of the 4-way splitter ports connected to sets or 'capped' with terminating resistors?

Broken, bent or missing elements are not going to improve the antennas performance. However, if only one of the longest elements is missing, I doubt the effect on the UHF channels will be much. In your area everyone is using high-VHF or UHF channels, K04QT is an exception but rabbitears.com indicates it is not on the air and you would need to use a rotator or separate antenna to get it anyway.

If you have been able to loosen the hardware to replace the matching transformer, I'm inclined to hold off from recommending replacement of the antenna... for now.

KIAH breaks up routinely. Local Channel 26 breaks up somewhat as well.

I can get a different cable and hook one TV directly to the new transformer that I put on the antenna. I suspect that I will have to move a TV to do this.

One of the 4 way splitter ports has a cap on it. The others have cables attached to them.

Yes, all original transformers/amps are now out of the system. I am on pure antenna power. Do you think if I put the transformer/pre-amp back into the system and get rid of all other transformers, this will boost the signal enough?

Does the "cap" look like this? Or is it just a dust cap? An un-terminated splitter port could cause trouble on one or two channels

A new cable between the antenna and one set will offer the most helpful diagnostic information at this point.

If I were offering suggestions for a all new antenna system, an amplifier would not be on the list of needed items. You should be able to receive enough power with a roof mounted antenna, to feed eight sets.

Tv Antennas and Reception
 

By giving an example of a 8 way splitter GUM is making a point that the Tv transmissions are strong. He is not saying install a 8 way splitter. I say that if 1 Tv is connected then use No splitters at all. I say that if 2 Tv's are connected then use only one 2 way splitter with the 2 outputs from the 2 way splitter going directly to the 2 Tv's with no other splitters in the coax lines. And the same with a 3 way splitter , the outputs of the 3 way splitter go directly to the 3 Tv's with no other splitters in the coax lines. There will be no splitters connected between coax the comes from the antenna and the input of , 2 way splitter , 3 way splitter , or 4 way splitter.

Tv Antennas and Reception
 

A "test cable" is simply a loooong length of RG-6 coax connected to matching transformer at the antenna and then directly to one Tv. The looooong length of cable can be run through a open door across floors to the Tv. Is the antenna on the outside of the building on the roof or is the antenna in the attic?? If the antenna is in the attic of the building structure , is the place where the antenna is at have a metal roof , is the building wrapped with any kind of metal. Is there any foil backed insulation in the attic?? What direction is the antenna pointed??

The cap looks like the one in the link you sent. I am pretty sure it is a terminator because it has the center wire in it. On a similar note, I do have an open jack in one of my rooms with no TV currently attached. Does this also need a terminator?

The antenna is mounted on a mast on the roof. It is pointed SSE. Today I plan to get a length of cable, attach it to the new transformer I put on the antenna, and then attach the other end of this cable directly to a TV somehow. This will eliminate all existing cabling.

JC's points are correct. The signals available to you are strong, you don't need an amplifier. If you have a need to split to two or more sets, the ideal method is to select a splitter with just enough ports. Unused ports need to be terminated, not left 'open' at the far end of a cable run.

John, thanks for clarifying the definition of 'test cable'.

I completed the test with a "good" cable directly to the transformer on the antenna and then to the TV on the other end. The reception on the poor channels was definitely improved. They are still not as strong as the "good" channels; but they appear stable at about 25dB. No improvement on the "good" channels. Do they ever get any better than about 30-32dB?

So, if you think the antenna is sufficient, I guess I must test the rest of the system piece by piece until I find the weak link.

Perhaps the next and easiest thing to test is to put a terminator on the open wall jack to see if this helps.

Signal metering on consumer grade receivers is generally, 'un-calibrated' and can be based on any combination of RF signal power and digital error rate. I don't know if your set can detect or indicate a higher signal quality value.

I agree, terminating the unused cable run, or the splitter port is the next step.

The cable from the antenna to the splitter is now high on my list of suspects. If water has ever entered the coax, it's done. Coax Seal is a good way to keep water from getting into the connectors exposed to weather.

I have now terminated all of the outputs from the system. I have also removed one length of outdoor cable that was not necessary. There appears to be some slight improvement in reception over my brief observation period but real channel 38 is still unstable.

I agree that the next logical step would be to replace the remaining outdoor cable that feeds into the attic splitter. I will have to evaluate this very carefully as it passes through my roof and I do not want better TV reception at the risk of a water leak.

Consider abandoning the old coax 'in place'. Can you run from the antenna down to the roof edge and enter the attic from the soffit?

I have now replaced all cable prior to the splitter. I have replaced the 4-way splitter with a 2-way splitter and disconnected the cable going to the room without a TV - so no open connections. Still having trouble on real channel 38. It goes from having a great signal to having a lousy signal and back again (12-28dB according to my TV).

I do not think that anything is wrong with my components, especially since they have all been replaced now and all of the other channels are stable. This is just a crappy signal...thank you digital TV.

I appreciate all the troubleshooting advice, JC and GUM.

Oh, one more thing. My new outdoor cable came with a ground wire. Where do you typically attach the ground- mast and cold water pipe?

A thread re. Grounding

If you stand behind the antenna and sight down the boom, does it point into the side of your neighbors house or large dense trees?

Have you inspected the cable and connectors on the cable from the splitter to the TV you are using as a meter?

The antenna is pointed towards a couple trees that are probably about 50 ft away. There are larger trees further away at maybe 100 ft. Nothing is right up on top of the antenna in the direction of the signals.

I have been monitoring the signals on both TVs and i did look at the connections. They are both behaving similarly. Behind the wall cables to the TVs are relatively new (3 - 5 yrs) compared to the other components that were in the system. I think they are unlikely to be the problem since both TVs exhibit similar behavior for all channels.

Do you think this brings up back to the antenna, which is where we started this conversation? Perhaps there are more optimal choices.

I don't think we have tried installing an FM Trap. They are fairly inexpensive and usually available at local Radio Shack stores, (returnable). The symptoms point toward a possible interference problem.

If I were building from scratch, I would use a modest sized 7-69 combo such as the HBU-22, HBU-33 or HD7694P. All of those antennas should have no trouble powering many more sets than you have at the moment. If we are fighting multipath, the larger Winegard antenna with it's more narrow beam width would be a better choice.

I would not install any sort of amplifier.

I have one more piece of factual information to add. After the frustration of not receiving KIAH (real channel 38) for some time, I decided to reposition the antenna again. When I moved it towards a more southerly direction (just about 180 degrees), the signal improved to the point where it was viewable. Unfortunately, all of the other station signals were lost. I have it back to where the majority of stations are ok and KIAH is passable at times. I was surprised by this behavior as I thought all of the towers were in the same location.

While the towers are in the same relative location, the signal doesn't always behave the way we want it to. You are likely experiencing what I call "frequency-specific multi-path". That usually means that you are getting an errant reflection off something on or near your line of sight that is interfering with the "primary" signal in a destructive nature.

The solution is to either try a more directional antenna (hoping to reject the reflection) or to move the antenna to a different location (up, down, left right) and try again, hoping that the new location is not bedeviled by the original reflection or a new one.

Same exact situation here (With another channel 38 no less) After much experimentation, the best solution was to aim the antenna 25° off axis for RF 38 with a rotator.

That's a classic symptom of an overloaded amplifier. Your signals are too strong for an amplifier anyway. I'd optimize and troubleshoot the system without the amp and the power supply and try to figure out why you thought that you needed it in the first place.