antenna reception problem please help

cclark746

DTVUSA Jr. Member
#1
this is my tvfool.

TV Fool

i have a antennacraft 1850hd. I can recieve 29.1,29.2,7.1,7.2,7.3 perfectly,and 12.1,12.2 cannot keep the signal. I cannot recieve any CBS channels at all. i can rotate my antenna and seems not to help for the loss of reception of 12.1 and 12.2. It takes 50ft of cable to get to my splitter on the outside of my house and prolly another 75ft to get to my living room tv which is my main one. i have it ran to 3 rooms total, but only really concerned about the living room. i do not have any amplifier currently. I could catch 29.1 with my indoor dollar store antenna lol. So all i gained out of spending 150$ is the 7's. Any advice would help me greatly.
THanks
cody:icon_beat:
 

Don_M

DTVUSA Member
#3
First, get coaxial terminators and screw them onto any unused coax connector in your system, whether at the splitter itself or the wall plates. Open connectors "leak" signals and may cause signal reflections in the cables; both conditions worsen reception. Terminators cost about a buck apiece, and should be available at the big-box home centers and Radio Shack stores.

If that doesn't help, the outdoor cable should be checked for wear. Carefully examine all coax connections at the same time for corrosion or water entry. Water, corrosion or damage can cause short-circuits or breaks in the antenna circuit. Reception suffers either way. This presumes the downlead is RG-6 coaxial cable. If it's not, or any wear or corrosion is noted, replace the downlead with RG-6. If the cable needs replacing, replace the coax transformer (attached to the antenna terminals) at the same time.

While troubleshooting the downlead, connect the antenna directly to only one of the TV sets, without any splitters, amplifiers or other TVs hooked up at the same time. That way, when reception is optimized on the gratest number of channels, you'll know any future reception issue isn't being caused by the downlead, the indoor cable leading to the TV or any of the connections along the way.

You do need an amplifier to get either of the CBS stations in your TVFool list, because both are fairly weak. However, the Fox and NBC stations are very strong, ruling out an antenna-mounted pre-amplifier. The best solution is a distribution amplifier installed before the splitter; this implies that you'll need to move the splitter, either into the basement or crawl space, so that it's located near an outlet for the amplifier. The Winegard HDA-100 distribution amplifier would be a good choice for this application.
 

cclark746

DTVUSA Jr. Member
#4
Thanks...
The antenna is brand new alone with the transformer. The cable is brand new rg-6 even got the more expensive one 4 time shielded are something like that. I cannot move the splitter into a basement are crawl space for i live in louisiana lol and basements would fill up with water lol...What about the ABC going in an out would a amp help that out? I am going to remove the splitter and just connect it straight to the main tv in my living room. Would the Winegard hda-100 distribution amp be a better choice for me are the channel master cm-7777? Thanks for all the info it was really helpful..
 

Don_M

DTVUSA Member
#5
OK, old, bad cable isn't the reason for poor reception, but was the cable handled properly when it was installed? RG-6 can short-circuit very easily if it's kinked, crushed, bent too hard or yanked too forcefully through holes. Check the insulation jacket carefully for permanent dents or bulges. Both are tell-tale signs the cable may be damaged and should be replaced.

Bypassing the splitter and running the downlead directly to the living-room TV is an excellent way to troubleshoot signal issues, but whatever you do, don't install an amp in the direct line: The Fox and NBC stations are far too strong for using any amp on one TV. You need the signal attenuation of the long downlead, splitter and additional distribution cables before even the HDA-100 is an option. (For another thing, don't crush the cable in a window or door frame to avoid shorts. Get one of these if there's no other way to get the downlead through the wall.)

A bigger amp in that signal situation is almost guaranteed to cause more reception problems than it solves thanks to amp and/or tuner overload. For this reason, the CM 7777 is totally out of the running there: It's designed for people at least 35 miles from the nearest transmitter. You're much closer than that to the Fox affiliate.

The TVFool report is arranged from strongest station to weakest. With that antenna above the roof, installed so that it's level, aimed correctly (about due east) and on 60 feet or less of RG-6 coax that's in good condition and attached to one tuner, you'll know you're on the right track when ABC affiliate KATC 3.1 comes in reliably, even without an amp. The antenna is good enough to do this by itself.
 

cclark746

DTVUSA Jr. Member
#6
Alright I will report back my findings tom. without running the splitter. Thanks for all the help you have been really helpful and I appreciate you taking your precious time to help the less DTV inclined lol. I was just in denver a week ago love that place, hate the traffic lol...thanks alot
cody
 

FOX TV

Contributor
#7
OK, old, bad cable isn't the reason for poor reception, but was the cable handled properly when it was installed? RG-6 can short-circuit very easily if it's kinked, crushed, bent too hard or yanked too forcefully through holes. Check the insulation jacket carefully for permanent dents or bulges. Both are tell-tale signs the cable may be damaged and should be replaced.

Bypassing the splitter and running the downlead directly to the living-room TV is an excellent way to troubleshoot signal issues, but whatever you do, don't install an amp in the direct line: The Fox and NBC stations are far too strong for using any amp on one TV. You need the signal attenuation of the long downlead, splitter and additional distribution cables before even the HDA-100 is an option. (For another thing, don't crush the cable in a window or door frame to avoid shorts. Get one of these if there's no other way to get the downlead through the wall.)

A bigger amp in that signal situation is almost guaranteed to cause more reception problems than it solves thanks to amp and/or tuner overload. For this reason, the CM 7777 is totally out of the running there: It's designed for people at least 35 miles from the nearest transmitter. You're much closer than that to the Fox affiliate.

The TVFool report is arranged from strongest station to weakest. With that antenna above the roof, installed so that it's level, aimed correctly (about due east) and on 60 feet or less of RG-6 coax that's in good condition and attached to one tuner, you'll know you're on the right track when ABC affiliate KATC 3.1 comes in reliably, even without an amp. The antenna is good enough to do this by itself.
Gary Srignoli, MSEE, independent DTV consultant, and former Zenith research engineer who helped develop the 8-VSB modulation scheme states in the current TV Technology magazine that he has yet to find a receive location that actually needed an amplifier. If the signal is there and above the background noise level, then you are normally dealing with a multi path, or other RF source of interference.

Mr. Srignoli has recently been hired by several VHF stations to troubleshoot their VHF problems in several markets, and he actually visits viewers homes to determine what problems may be causing reception issues. He has found that high RF energy sources that are not even on frequency with dtv channels can actually cause reception problems.

Items such as leaking cable TV signals, light dimmers, fan speed controllers and even electronic florescent ballasts can all be detrimental to DTV reception, even when the RF sources frequency is not near the DTV spectrum. Simple RF front end overload will cause issues too.

In the case of VHF channels, being near a strong FM transmitter on certain frequencies where second and third order harmonics can also cause reception issues that at first may seem like antenna or equipment problems. The only way to know for sure is to have someone from the TV station that has some test equipment come to the location and look at the spectrum on an analyzer to see what signals actually exist at some extreme locations.

Some cases of reception issues can be difficult for the viewer to troubleshoot on their own. I agree that the majority of reception issues can be traced to improper antennas or installation problems, or some other issue with the viewers equipment or environment.
 
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JER

DTVUSA Member
#8
Its been my general feeling for quite a while now that for many people reception problems are usually related more to signal quality than signal strength.

The above post by FoxTV indicates how complicated the signal environment can be and how difficult it can be to resolve these kinds of problems without a truck load of test equipment.

Probably the simplest way to avoid a lot of these problems is to get the antenna outside and to avoid amplifiers.

Putting the antenna outside helps reduce the impact of household noise sources. It also dramatically increases signal level and reduces the effect of indoor multi-path.

While amplifiers increase signal level, they always add something (e.g. noise, harmonic distortion, and inter-modulation distortion) that's not actually on the air. A cheap amp can easily saturate on a strong in-band or even out-of-band signal and generate a wide spectrum of "crud" that makes it impossible to detect anything with the receiver. By starting off without an amp, you can make a better determination of what your true signal situation is like. Then, if you're missing some weak stations you can add the amp and see if it really helped.
 

FOX TV

Contributor
#9
Amps !!

Its been my general feeling for quite a while now that for many people reception problems are usually related more to signal quality than signal strength.

The above post by FoxTV indicates how complicated the signal environment can be and how difficult it can be to resolve these kinds of problems without a truck load of test equipment.

Probably the simplest way to avoid a lot of these problems is to get the antenna outside and to avoid amplifiers.

Putting the antenna outside helps reduce the impact of household noise sources. It also dramatically increases signal level and reduces the effect of indoor multi-path.

While amplifiers increase signal level, they always add something (e.g. noise, harmonic distortion, and inter-modulation distortion) that's not actually on the air. A cheap amp can easily saturate on a strong in-band or even out-of-band signal and generate a wide spectrum of "crud" that makes it impossible to detect anything with the receiver. By starting off without an amp, you can make a better determination of what your true signal situation is like. Then, if you're missing some weak stations you can add the amp and see if it really helped.

I agree with your thoughts on amplifiers. I think they are overused to the point of causing problems instead of solving them. An amplifier is the last thing I would recommend to try and solve reception issues. This is based on my last 2 or so months doing field strength tests in our market that has very mountainous terrain. I have received signals from ours, and other transmitters in this rough reception terrain at 75 miles out, and still had plenty signal head room for good reception using a Clear Stream C2 at only 20 feet elevation.

I have seen this same scenario at many different locations in our rigorous signal testing project. I use a Rhode & Swartz FSH-3 TV Analyzer for signal analysis, along with a Sencore DTU 36 transport stream analyzer to look for echo strength and amplitude, and for echo timing to see how far out on the time line the echos are in highly problematic areas. It seems that most of the multi path issues are from reflective objects that are relatively close to the receive location instead of miles out as in analog.

I have not seen one location at that distance that if enough signal strength was there that I could not receive the signal, and have not really seen a situation where an amplifier would solve any reception problems. We have even seen situations on the Rhode & Swartz Analyzer where the signal was almost near the SNR of the tuner that we were using, but the gain of the C2 would still allow reception of weaker signals WITHOUT an amplifier.
 

SWHouston

Moderator
Staff member
#12
Fellas,

I apologize for jumping on your suggestions, I may should have let one of you follow through on this. However, I think this issue of when and what Pre-Amp is very important, frequently abused as you have said, and went ahead and started a new thread on the subject at....

Pre-Amplifiers, Usage & Reviews

I sincerely hope there will be some very informative discussions on this issue, and again, sorry about being so forward.

Have a good Day ! :dancing:
S.W.
 

pmr

DTVUSA Member
#13
A few questions to reduce Fox TV and JER's recent discussion about reception and amplifiers to practical terms even I can understand and use to improve my lousy tv reception. No intent to put anyone on the spot; just a genuine interest in "getting it".

a) signal quantity is what's available at my antenna location?

b) signal quality is signal quantity reduced by line leakage and sources of RF noise between my antenna and my tv?

c) the signal at my antenna is similarly reduced by a quality component, i.e., distance and obstacles between the transmitter and my antenna?

d) even with low signal quantity I might have adequate reception if signal quality is high?

e) a (low noise) pre-amp is best used where: e2) signal quantity at the antenna is marginal; and/or e3) you have distribution losses (distance, cheap cable, splitters) between the antenna and tv(s)?

f) "NM" or "noise margin" on tvfool reports is the result of an analysis of "background noise" between the transmitter and my location?

g) is it possible to recieve a signal from a negative NM source?

h1) if my antenna is outside, do I need to worry about leaking cable tv signals, light dimmers, speed controllers and flourescent ballasts? h2) Do microwaves, wireless routers, and radio frequency remotes affect reception with inside antenna? Outside antenna?

i) assuming our "multi path issues are from reflective objects that are relatively close to the receive location", what can we do about it?

j) Fox TV, can you clarify this sentence: "I have not seen one location at that distance that if enough signal strength was there that I could not receive the signal, and have not really seen a situation where an amplifier would solve any reception problems."

That must mean more than: if there's a strong enough signal to have reception I'll have reception. j2) Is the point that most reception problems are not signal strength problems? Is the point that most reception problems are: j3) insufficient gain antenna; or j4) line losses? These seem to be common sense. Is there something more complex I'm not getting? [again, no interest in playing "gotcha"; just trying to "get it"...]

k) should I expect (hope?) a C2 at 20 feet above grade will capture my stations at the antenna (before distribution)? My stations are 30 to 50 miles, over water and through trees, some uhf and high vhf are 1 to 2 edge multipath, all NM's are above 16dB? (leaving aside for this question the fact that transmitters are in 3 general directions 20 - 49 degrees apart)

l1) my uhf antenna is not the highest gain antenna available (42xg). with no pre-amp I get no uhf reception; with a CM7777, I get uhf reception that varies with aim and weather. would a higher gain antenna grab more signal ( l2) how do I know if there's more signal available?) and l3) reduce the gain needed to be supplied by a pre-amp?

Sorry, I guess that's all a bit much but I hope some of you will tackle some of these questions for the benefit of the rest of us non-engineers and non-hobbyists trying to recover tv lost upon the digital transistion.
 
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