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22-Aug-2016, 2:07 AM
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#21
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Retired A/V Tech
Join Date: Aug 2012
Location: S.E. VA
Posts: 2,747
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Quote:
So, based on your post, and studying other links/docs, I think I want to achieve a NM of 0 at least (preferably 5 or 10 NM, to give myself buffer, otherwise I'd probably have frustrating viewing experience having signal drop below threshold quite often due to random events).
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Correct, you want a Fade Margin of at least 10 dB because OTA signals constantly vary in strength.
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Antennas comes with gain that will add to the NM (says here that antenna is the only one that I can really add to NM
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Yes, antenna gain can be directly added to make the NM more positive. You can also add the amp gain but must subtract the amp Noise Figure which reduces the signal SNR. You might wonder why would you want to do that if it reduces the SNR of the signal coming from the antenna? The answer is that a preamp reduces the total System Noise Figure making the distribution losses minimal and making it possible to receive signals that are about 5 dB weaker because it makes the tuner noise figure irrelevant.
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22-Aug-2016, 2:14 AM
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#22
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Retired A/V Tech
Join Date: Aug 2012
Location: S.E. VA
Posts: 2,747
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This website compares antennas, but it is a little out of date. Use the net gain figures.
http://www.hdtvprimer.com/antennas/comparing.html
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How much gain would I get from the HD7694P?
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http://www.winegard.com/kbase/uploads/HD7694P.pdf
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Shoot, forgot to ask before I order. Does HD7694P have decent wind load numbers at least? Florida here, so we have storms.
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I don't know. Why don't you call them and ask them. They have been making antennas for a long time, so I assume they know about Florida, and have designed for that.
Last edited by rabbit73; 22-Aug-2016 at 2:30 AM.
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22-Aug-2016, 8:21 AM
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#23
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Member
Join Date: Oct 2011
Posts: 55
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Originally Posted by cflannagan
Ha - if you remember details about each antenna - whether they're suited for UHF, VHF-HI, VHF-Low, without using a reference website, that's even more impressive :-D
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You do not need to remember details. There are data sheets, you can read reviews on Amazon, and you can google an antenna for more discussion. There is a lot of debate over which antenna is best, but general consensus on which antennas are good for a specific situation. I don't think many would argue against coupling a DB8e or a 91XG with a 30-2476 for fringe viewing where vhf and uhf stations are in different locations, for instance. I don't think anyone would argue against one of the Winegard combo antennas for your situation.
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28-Aug-2016, 10:26 AM
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#24
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Junior Member
Join Date: Aug 2016
Posts: 13
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Would like to thank everyone, the recommendation for HD7694P was spot on!
The 8.1 channel (NBC), the one I was having most problems with (despite it being most solid when I was trying my first antenna, an omnidirectional) is now solid, and stays up even during storms, whereas previously with HDX4 I would get complete loss of signal or extreme pixellating!
Without amplifier, I get something like 20 or so channels, and with it I get 55+.
I haven't actually tried watching the major networks (NBC, CBS, FOX, ABC) for extended periods of times without amplifier. But it seems to be okay with amplifier, and would like to keep using it, particularly since I get more channels with it.
What does the symptoms of an overloaded tuner look like, exactly? (for my future reference so I know what to watch for).
Once again. thanks rabbit for the antenna recommendation! Seems stable enough that I've went ahead and ordered a OTA DVR for our house!
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28-Aug-2016, 2:35 PM
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#25
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Retired A/V Tech
Join Date: Aug 2012
Location: S.E. VA
Posts: 2,747
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Thanks for the good news; glad you like the reception results.
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What does the symptoms of an overloaded tuner look like, exactly? (for my future reference so I know what to watch for).
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You will usually see pixelation of the weakest signals first.
The strongest signals create spurious signals from IMD (Intermodulation Distortion) that raise the noise floor and reduce the SNR of the weakest signals to less than the minimum required 15 dB.
Here is a spectrum analyzer display of the Antennas Direct Eclipse antenna in a strong signal area without a preamp:
Here is the signal display when an overloaded Mohu Jolt amp has been added:
Last edited by rabbit73; 28-Aug-2016 at 2:53 PM.
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