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post #8581 of 8584 Old 08-09-2015, 03:04 PM
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Originally Posted by Rick313 View Post
I haven't noticed any issues, and I'm no expert, but I have a few thoughts:

1. Are you using any sort of amplification? If so, it could be that KMGH is overloading the tuner. I would try disconnecting the amplifier and see if that makes a difference.

2. Since KMGH is broadcast on two different RF channels (7 and 17) with the same virtual channel numbers, that may confuse some tuners. If your TV has the ability to scan for a specific station, you might try scanning for channel 7 or channel 17 by itself. If you can't receive channel 7 for some reason, it's likely that you will be able to receive channel 17 or vice versa. They both broadcast the same content, so you won't be missing anything either way.

3. I assume that you are using an antenna that is optimized for both VHF and UHF reception. If not, then I would switch to an antenna that is optimized for both since Denver has multiple VHF stations.

Hope some of this helps. Have a great day!
Thanks for the suggestions.
I do have an amplifier (see below).
Unfortunately I cannot scan for individual channels.
My antenna says that it is a VHF/UHF/FM/Digital antenna so I don't think that is an issue.


I disconnected the amp and still cannot pick up KMGH on my DTV. However, I also have an analog TV with a digital converter box connected to the same antenna and now interestingly KMGH comes in. It is at a much lower signal strength (66) than KUSA (88) or any of the others broadcasting from Lookout Mountain. I also can see other stations on this TV that are not detected by my DTV. Is it possible that my DTV is ignoring signals below a certain strength level? Another anomaly here is that the analog TV picks up CPT12 (Colorado public tv) with a signal strength in the 80s but the DTV doesn't get it all. I have rescanned several times and always get the same channels on my DTV. Neither 7 or 17 are registered.
Maybe my 6 year old DTV tuner is just not sensitive enough.


I appreciate your comments.
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post #8582 of 8584 Old 08-09-2015, 04:06 PM
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Originally Posted by jsmar View Post
When you say you get KUSA, do you get it on 9.1 or do you get it on 9.4? The reason I ask is that if you are trying to receive KUSA or KMGH on a UHF only antenna you're going to have inconsistant results, since their main signals are on VHF frequencies. However, KUSA also broadcasts their main program on KTVD's UHF signal using 9.4 as the virtual channel. KTVD's UHF signal is a high power signal so it should be easy to receive. KMGH also broadcasts on UHF using KZCO's UHF signal, but KZCO is a low power station, which may be more difficult to pick up. Also, they use the same virtual channel numbers, so when you receive 7.1 you may not know whether you are getting the VHF signal or the UHF signal, depending on how your particular tuner deals with duplicate virtual channel numbers.

Anyway, from Fort Collins I haven't seen any significant issues with KMGH's signal (according to my logs they had a little bit of a signal drop yesterday, and that has been the worst problem they've had in a really long time), and I have an automatic process monitoring all TV channels in Denver and Cheyenne (and occasionally other stations that might pop up via DX reception) 24 hours a day.

Note of course that their VHF antenna is made up of multiple antennas pointing in different directions, so there is the possibility that I may never observe a problem that is caused by an antenna issue, but everything else in the chain is common to what I receive.

Again, if you're antenna isn't designed for VHF reception then you're going to have issues, and even if you are receiving KUSA's VHF signal with a UHF antenna, the fact that you can't receive KMGH the same way may have nothing to do with KMGH, but has everything to do with the fact that an antenna's reception outside its designed bandwidth can vary hugely over fairly small differences in frequency.


Thanks for responding.
My antenna is capable of receiving UHF/VHF/FM/Digital so I don't think that is my problem. I used to receive KMG (7.1, 7.2, 7.4) with no problems up until a few months ago.
On my DTV I am receiving KUSA on 9.4. I also have an analog TV with a digital converter that receives KUSA on 9.1 through 9.4. KUSA 9.4 is at a signal strength of 88 while, as you indicated, 9.1 through 9.3 are at a lower signal strength (66). My DTV does not show signal strength.


At the suggestion of another member I disconnected my amplifier and now the analog set receives KMGH 7.1, 7.2 and 7.4 (I think) at a signal strength of 66 but they show up as KMGH 82-1, Azteca 82-2, and LAFF TV 82-3 even though they are displayed sequentially between channels 6 and 9.


After many rescans my DTV does not register any of them. Interestingly my analog set also receives many other stations that my DTV does pick up. Several of these stations have relatively low signal strengths (60s) but KBDI (PBS channel 12) has a strength in the 80s yet my DTV doesn't pick it up.
The DTV is 6 years old so maybe the tuner is just wearing out, if that's possible.


Thanks for your comments.
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post #8583 of 8584 Old 08-10-2015, 03:37 PM
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Originally Posted by rbsfinav View Post
Thanks for responding.
My antenna is capable of receiving UHF/VHF/FM/Digital so I don't think that is my problem. I used to receive KMG (7.1, 7.2, 7.4) with no problems up until a few months ago.
On my DTV I am receiving KUSA on 9.4. I also have an analog TV with a digital converter that receives KUSA on 9.1 through 9.4. KUSA 9.4 is at a signal strength of 88 while, as you indicated, 9.1 through 9.3 are at a lower signal strength (66). My DTV does not show signal strength.


At the suggestion of another member I disconnected my amplifier and now the analog set receives KMGH 7.1, 7.2 and 7.4 (I think) at a signal strength of 66 but they show up as KMGH 82-1, Azteca 82-2, and LAFF TV 82-3 even though they are displayed sequentially between channels 6 and 9.

After many rescans my DTV does not register any of them. Interestingly my analog set also receives many other stations that my DTV does pick up. Several of these stations have relatively low signal strengths (60s) but KBDI (PBS channel 12) has a strength in the 80s yet my DTV doesn't pick it up.
The DTV is 6 years old so maybe the tuner is just wearing out, if that's possible.


Thanks for your comments.
I don't think it is possible for a tuner to "wear out", but it could certainly be damaged by either a power surge, lightning strike, or even a static discharge. But I doubt any of those are what are causing your problems.

I also doubt that the amplifier was causing a signal overload on KMGH. That was more of an issue with older equipment, whereas your equipment, although "old" for the digital tuner age, could probably handle significant signal strength (note I am not saying the issue is definitely not due to signal overload).

If removing the amp helped, my theory is that the amp wasn't very good in the first place. There are many bad amps out there, which tend to boost the signal, but add more noise or distortion at the same time, which damages the signal rather than helping, especially for digital.

In most cases, I don't recommend a distribution amplifier be used. It's much better to use a quality antenna pre-amp installed right at the antenna, which preserves the signal at the point of reception and boosts it enough for good distribution. You can choose an appropriate version depending on how many passive splitters you need after the preamp. Again, a low quality pre-amp will hurt more than it helps. An antenna pre-amp is especially helpful if there is a long run of coax from the antenna to the TV (which is typically the case with an outdoor antenna).

Since you're reception changed, it most likely is due to something having changed at your location, or between your location and the broadcast antenna. Older digital tuners were highly susceptible to multipath distortion, i.e. the signal coming from mulitple paths, due to reflection off of other things. Even if you have a clear line of sight to Lookout Mountain, you could still be affected by this. Newer generation digital tuners are a lot better at handling multipath distortion.

So, any new tall buildings erected nearby? New houses that block your line of sight to Lookout Mountain? Trees in your line of sight (particularly close to the antenna, i.e. your yard or a neighbors yard) grow bigger over the last few years?

Another possibility is connection or even coax degeneration over time. Especially for the outdoor connections (since you say your antenna is installed outdoors). In particular moisture can get into connections if they aren't properly weather sealed.

Yet another possibility is antenna damage. If your antenna is a true UHF/VHF antenna, the VHF component may have longer elements that could be damaged in high wind. Are you sure you still have all your antenna elements?

I will also note that some unscrupulous antenna manufacturers may market an antenna designed for UHF reception as UHF/VHF if it has any sensitivity at all in the VHF range. Do you actually have some documentation regarding antenna gain in the VHF (high VHF in particular) range? What antenna do you have?

Also, can you share more about your installation, i.e. besides antenna model, things like how long the coax run is, what type of coax was used, what if any splitters are in the signal path, what kind of distribution amp were you using, etc.

On another note, if your digital converter box is using 82 as the major channel number for your KMGH subchannels, that is an indication that it is receiving both the KMGH signal and the KZCO signal, and it is choosing to put one of them in the 82 range to resolve the conflict of the duplicate channel numbers. It's not clear why there isn't another set at 7.1, etc. Some tuners don't handle duplicate channel numbers well at all.
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post #8584 of 8584 Unread Today, 09:16 AM
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KMGH Problem Solved

Quote:
Originally Posted by jsmar View Post
I don't think it is possible for a tuner to "wear out", but it could certainly be damaged by either a power surge, lightning strike, or even a static discharge. But I doubt any of those are what are causing your problems.

I also doubt that the amplifier was causing a signal overload on KMGH. That was more of an issue with older equipment, whereas your equipment, although "old" for the digital tuner age, could probably handle significant signal strength (note I am not saying the issue is definitely not due to signal overload).

If removing the amp helped, my theory is that the amp wasn't very good in the first place. There are many bad amps out there, which tend to boost the signal, but add more noise or distortion at the same time, which damages the signal rather than helping, especially for digital.

In most cases, I don't recommend a distribution amplifier be used. It's much better to use a quality antenna pre-amp installed right at the antenna, which preserves the signal at the point of reception and boosts it enough for good distribution. You can choose an appropriate version depending on how many passive splitters you need after the preamp. Again, a low quality pre-amp will hurt more than it helps. An antenna pre-amp is especially helpful if there is a long run of coax from the antenna to the TV (which is typically the case with an outdoor antenna).

Since you're reception changed, it most likely is due to something having changed at your location, or between your location and the broadcast antenna. Older digital tuners were highly susceptible to multipath distortion, i.e. the signal coming from mulitple paths, due to reflection off of other things. Even if you have a clear line of sight to Lookout Mountain, you could still be affected by this. Newer generation digital tuners are a lot better at handling multipath distortion.

So, any new tall buildings erected nearby? New houses that block your line of sight to Lookout Mountain? Trees in your line of sight (particularly close to the antenna, i.e. your yard or a neighbors yard) grow bigger over the last few years?

Another possibility is connection or even coax degeneration over time. Especially for the outdoor connections (since you say your antenna is installed outdoors). In particular moisture can get into connections if they aren't properly weather sealed.

Yet another possibility is antenna damage. If your antenna is a true UHF/VHF antenna, the VHF component may have longer elements that could be damaged in high wind. Are you sure you still have all your antenna elements?

I will also note that some unscrupulous antenna manufacturers may market an antenna designed for UHF reception as UHF/VHF if it has any sensitivity at all in the VHF range. Do you actually have some documentation regarding antenna gain in the VHF (high VHF in particular) range? What antenna do you have?

Also, can you share more about your installation, i.e. besides antenna model, things like how long the coax run is, what type of coax was used, what if any splitters are in the signal path, what kind of distribution amp were you using, etc.

On another note, if your digital converter box is using 82 as the major channel number for your KMGH subchannels, that is an indication that it is receiving both the KMGH signal and the KZCO signal, and it is choosing to put one of them in the 82 range to resolve the conflict of the duplicate channel numbers. It's not clear why there isn't another set at 7.1, etc. Some tuners don't handle duplicate channel numbers well at all.
Thanks for all of the suggestions and I apologize for taking so long to respond.
I found my problem:
When I looked at everything that I had installed I realized that all of my coax cable was RG6 with the exception of the run from a splitter to my main TV (the one I was having trouble with). That was RG59. I replaced that section of cable, making sure that the end connectors were in good shape and, Voila, I now receive around 65 channels instead of the 29 I was getting before. KMGH is coming in fine. Although the tuner on my TV shows 2 channels each for 7.1, .7.2, & 7.3. I can live with that. I just hide one of each.
Again, thanks for the help.
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