Help with Reception / Antenna Setup

[cmihai]

Anybody can shed some light on the following?

CW, PBS and Fox are at the same distance (64 miles) and same azimuth (161 magnetic) from my location. I get CW and PBS and about 40-50 signal strength with a max of 60 (out of 100). However, Fox doesn't get through at all. Signal Noise Margin is 19.2 (CW), 10.2 (PBS) and 8.5 (Fox). There is not much difference between PBS and Fox in NM, and I can get one but not the other.

At the same time, I get ABC at the same azimuth (161 magnetic) at 95 miles away with a NM of 6.6! And NBC at 171 magnetic and 92 miles away with a NM of 5.5.

How can this be explained? Do I need a more powerful preamp? I calculated my losses at 17 db (3 db preamp, 6 db 100 ft coax cable, 8 db 4 way splitter), reason I opted for a 19 db gain preamp. Does the built-in TV tuner introduce signal loss too? Should I go with Winegard AP-8275 / 4800 (28 db gain)?

TV Fool Analysis Results
http://www.tvfool.com/?option=com_wr...03d944daf69fe2

Antenna Setup: Antennas Direct DB8, Winegard AP-8700 Preamp, approx 80 ft RG6 coax cable to the 4-way splitter, Sony Bravia with built-in tuner

[John Candle]

Yes the lack of reception is explained as one or all of these , multipath or interference from other types of transmitters such as Fm radio transmitters or other types and kinds of transmitters such as but not limited to other Tv transmitters both analog and digital tv transmitters. I suggest use a FM trap. It does help to have the coax grounded with a coax grounding block to electric service ground. Or if not able to do electric service ground , then a cold water pipe ground or drive a ground rod. . Tuners of any type , introduce noise , noise masks the desired signal , amplifiers also introduce noise and - noise - puts an over lay of , from a certain point of view a ' fuzz' over lay on the desired signal. Also the lack of reception can be using a incorrect antenna.

[John Candle]

It looks like cmihai has other posts for this reception situation. http://forum.tvfool.com/showthread.php?t=1864

[John Candle]

A I recommened before , I still recommened the Winegard HD7698P antenna. I still recommend start with the same aiming directions and turn antenna for best reception. And every thing else I provided is still true.

[John Candle]

A I recommened before , I still recommend the Winegard HD7698P antenna. I still recommed start with the same aiming directions and turn antenna for best reception. And every thing else I provided is still true. If you will answer the questions about the splitter I can recommend a different amplifier that will provide better reception.

[cmihai]

Thank you for feedback John.

Some clarifications: Winegard AP-8700 has two FM traps, a fixed and a variable one. I haven't altered factory settings, just made sure that the fix FM trap is on. Haven't played with the variable at all.

The coax is grounded to a grounding block (actually a combination of grounding block and lightning arrestor - TII 212 Broadband Cable TV Lightning Surge Protector), connected to an 8-foot copper clad rod and bonded to the house service ground.

The splitter is a Channel Master 4 way splitter.

Interesting fact: prior to the pre-amp installation and with no splitter I was able to get Fox quite good (at 55-65 out of 100) with very weak ABC (10 out of 100). Of course I have tried many different aiming positions since then and can't seem to remember the exact position.

Aiming the antenna seems to be the pain point: I have tried 181 magnetic degrees (everything is an approximation anyway, how can I be absolutely sure?) and I don't seem to get the most out of it. The most channels and at the farthest distance are at 161 magnetic degrees.

To be honest with you, I've struggled to understand why I should be aiming the antenna at 181 magnetic. 181 magnetic and above yields only three channels: CHCH-DT on 11.1 (green zone), CITS-DT on 36.1 (yellow zone) and WNYB-DT on 26.1 (red zone) - I'm not particularly keen with any of these.

How would this position help with NBC on 2.1 (157 magnetic)? Would this position help with following channels at 161 magnetic: PBS on 17.1 and Fox on 29.1 at 64 miles? CBS on 4.1 at 93 miles? ABC on 7.1 at 95 miles?

Thank you!

[cmihai]

How can I possibly know that upgrading to a higher gain (e.g. from 19 to 28) wouldn't burn the TV tuner / receiver?

That is one the reasons I opted for the second in line pre-amp gain in the first place.

[John Candle]

Many people have no idea and I mean No Idea at all what direction is what direction . Antenna aiming is a process. The direction in degrees is given , this get's the antenna pointed in the direction the antenna will need to be pointed at and then the antenna is turned to the left and right to get the best reception of the channels the person will like to receive. In your case I gave a direction that is in between the two groups of stations and then you turn the antenna for best reception. As time goes along I change my wording so that more people can and will understand. You must understand that we are dealing with some people here that do not even understand the , north , south , east and west. Think about it , if you were using words only and you were explain how to aim a Tv antenna , what words would you use??

[John Candle]

Amplifiers - Will Not - burn out - a Tv tuner. Are the 4 out put ports of the splitter being used??. Question . The second in line preamp gain??

[cmihai]

All right John, I now understand that 181 magnetic degrees is more of a starting point. From the post I thought that only minor corrections to 181 magnetic are acceptable, my mistake.

Since - in my case - most of the channels are at around 161 magnetic, including the farthest ones, the best and final direction might well be different than the starting point suggested. Thank you!

[cmihai]

Two of the splitter outputs are connected (to one TV each), one has a coax F terminator and the last output is currently wide open (I realize this is not the ideal situation). Later on I'd need to connect it to the third TV in the basement.

The highest (first in line) pre-amp gain is at about 28 db on UHF. The second (in line) comes at about 19 db UHF. I red that the pre-amp is supposed to compensate for cable loss and should not provide much more than the actual cable loss, otherwise it might burn out the TV tuner (if I'm not mistaken). As mentioned in the first thread, my cable loss is at about 17 db that is why I decided to go with a 19 db pre-amp gain. I was afraid that 28 db would be too much of a good thing

[ADTech]

It's not possible to burn out or otherwise damage a tuner with a signal that's too strong, except, perhaps, by using extraordinary (think military-level powers) measures.

An overload tuner simply stops operating until the overload condition is removed.

[cmihai]

Got you, ADTech.

Is is possible to know in advance what the ideal preamp gain should be? On one side we have cable loss (which is relatively straightforward to calculate). A few db on top of that should be fine, however too much would lead to overloading. How can someone figure out the sweet spot?

[cmihai]

Got you, ADTech.

Is is possible to know in advance what the ideal preamp gain should be? On one side we have cable loss (which is relatively straightforward to calculate). A few db on top of that should be fine, however too much would lead to overloading. How can someone figure out the sweet spot?

[GroundUrMast]

Originally Posted by cmihai

... I calculated my losses at 17 db (3 db preamp, 6 db 100 ft coax cable, 8 db 4 way splitter), reason I opted for a 19 db gain preamp. Does the built-in TV tuner introduce signal loss too? Should I go with Winegard AP-8275 / 4800 (28 db gain)?

TV Fool Analysis Results
http://www.tvfool.com/?option=com_wr...03d944daf69fe2

Antenna Setup: Antennas Direct DB8, Winegard AP-8700 Preamp, approx 80 ft RG6 coax cable to the 4-way splitter, Sony Bravia with built-in tuner

Originally Posted by cmihai

Two of the splitter outputs are connected (to one TV each), one has a coax F terminator and the last output is currently wide open (I realize this is not the ideal situation). Later on I'd need to connect it to the third TV in the basement.

The highest (first in line) pre-amp gain is at about 28 db on UHF. The second (in line) comes at about 19 db UHF. I red that the pre-amp is supposed to compensate for cable loss and should not provide much more than the actual cable loss, otherwise it might burn out the TV tuner (if I'm not mistaken). As mentioned in the first thread, my cable loss is at about 17 db that is why I decided to go with a 19 db pre-amp gain. I was afraid that 28 db would be too much of a good thing

I don't understand why you attribute 3 dB of loss to a preamp. If you are considering the noise figure, it is not attenuation and can not be overcome with amplification (it's unwanted noise generated by the amplifier added to the desired signal).

You indicate 80' of RG-6 and a 4-way split. My calculation says you are facing a total of 13 dB of loss due to cable and splitters.

There is no reason to be using two amplifiers in the system you describe. The long list of strong local signals indicates against use of any amplifier with low to moderate input capability. A second amplifier in-line will most certainly be overloaded even if the first amplifier is not.

Either the Winegard HDP-269 (which I think JC recommended) or an Antennas Direct CPA-19 would be all the amplifier I could recommend. My inclination is toward the CPA-19. Both amplifiers are resistant to overloading, the CPA-19 has a better noise figure.

Per your TVFR, WUTV-FOX, real channel 14 arrives at your location with an available NM of 8.5 DB (signal level of -82.3 dBm). The DB-8 is not known for peak gain at the bottom of the UHF band. IF if has 10 dBd gain at CH-14, that can be added to the NM of 8.5 dB providing a NM of 18.5 dB (signal level of -72.3) to the preamp input. The CPA-19 has a NF of about 2 dB which will subtract from the NM ant the preamp input, now we have a NM of 16.5 (signal level of -72.3 + 17 dB amplifier gain = -55.3 dBm at the amplifier output.) After that signal passes through 13 dB of cable and splitter attenuation the signal level at the tuner input would be -68.3 dBm, not the strongest signal in the world, but sufficient for a decent tuner to work with... IF there is no significant external interference problem, AND, the TVFR prediction is accurate.

There are better antennas for reception of real channel 14. The Antennas Direct XG-91 for example. If the 2-edge path for WUTV is introducing unpredicted loss or multipath or, there is external interference, you may never see reliable signal from WUTV. As a test, you can remove the splitter and check to see if you can see WUTV, if you see it, you may be lucky and simply be facing lower than predicted signal levels.

[cmihai]

Originally Posted by GroundUrMast

There is no reason to be using two amplifiers in the system you describe. The long list of strong local signals indicates against use of any amplifier with low to moderate input capability. A second amplifier in-line will most certainly be overloaded even if the first amplifier is not.

Allow me to clarify this please: there is only one preamplifier in the system, Winegard AP-8700, as posted in the first thread. We were discussing options. My understanding is that any (pre)amplifier cannot increase the signal level beyond that of the native (over the air) and antenna gain combined, it can only compensate for signal loss. With this in mind and given that signal loss in my case can be recovered by one preamplifier, I do not see the point of adding a second amplifier.

Originally Posted by GroundUrMast

There are better antennas for reception of real channel 14. The Antennas Direct XG-91 for example. If the 2-edge path for WUTV is introducing unpredicted loss or multipath or, there is external interference, you may never see reliable signal from WUTV. As a test, you can remove the splitter and check to see if you can see WUTV, if you see it, you may be lucky and simply be facing lower than predicted signal levels.

Thanks for all other suggestions, I'd give it a try and get back to you.

I believe my aiming is currently not so great for WUTV-FOX, as I get WNYO-DT on 49.1 at 153 magnetic and 91 miles away quite solid at 40-50 out of 100. Rated NM is 1.6 db with a signal level of -89.2 dbm, signal path 2Edge. By all accounts, this looks so much worse than WUTV-FOX.

Thanks again!

[Billiam]

cmihai. It may very well be the tuner in the TV that is a problem. A little over a year ago I went to Wal Wart and bought a 32" Sanyo HDTV. I set it up here and noted that it did not always receive all of the channels that came in on my Samsung 32" which was purchased at about the same time. I returned the Sanyo and bought a Sony and the Sony turned out to have a tuner that is even more sensitive than the Samsung. While both the Samsung and Sony get the same stations even during skip conditions, the Sony signals are usually a bit stronger and don't break up or fade out as fast when the skip condition start to fade.

[John Candle]

I currently agree. Sony has the latest 'digital generation' of of tuner technology and so does Samsung.

[John Candle]

I did my best to recommend what it will take for reliable reception. cmihai is erecting too many variables that result in bad or no reception. Put out 2 fires and 4 more are started by cmihai. I have no more help to offer.

[Billiam]

cmihai. See if a friend or neighbor or two will bring over a HDTV for you to set up to compare. If you still don't get this channel on at least two other televisions (preferably a different brand from your existing unit) then we could probably rule out the problem is with your tv tuner. Start here first. This is a cheap way to troubleshoot the problem.