CM-7777 / 7778: "New & Improved"? - Page 5 - AVS Forum | Home Theater Discussions And Reviews
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post #121 of 132 Old 10-15-2014, 12:56 AM
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As mentioned, the biggest and best combo antennas for High VHF and UHF are the Winegard 7698 and the Antennacraft HBU-55. In the large all band category, there is the Winegard 8200, Channel Master 3671 or 3020, and the Antennacraft 1850 or C490. But as said, you do not need Low VHF, so the large all band antenna is unnecessary. As for UHF, the best fringe antennas are the 91XG from Antennas Direct, Winegard 9095, Antennacraft MXU59, or possibly any of the DB8 versions. And there is also a triple boom yagi from MCM/Stellar Labs that is somewhat modeled after tthe Televes DAT75. But in your case, I would go with the 7698 Winegard, although at 50 miles even the 7696 or HBU-33 from Antennacraft should work. But I would probably choose Winegard because the build quality should better withstand winter weather conditions.
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post #122 of 132 Old 10-16-2014, 01:02 PM
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Thanks a Bunch
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post #123 of 132 Old 02-11-2015, 08:58 PM
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A Original version of the CM 7777 is for sale here for anyone interested in the lower noise figure 2.0db and two inputs. From 2011-2012. http://www.ebay.com/itm/Channel-Mast...item3aa290df0e

Thanks.
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post #124 of 132 Old 02-12-2015, 03:34 AM
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The older ones were never as low a noise figure as advertised.
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post #125 of 132 Old 02-28-2015, 07:36 AM
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Ugh. Think my "old style" 7777 has bitten the dust. Power making it up coax fine, but signals shot. Opened up preamp, and looks like a singe on the board.

Trying an RCA TVPRAMP1R in its placeClick image for larger version

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post #126 of 132 Old 03-13-2015, 05:46 AM
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FWIW, the RCA is giving me significantly better results than my "old" 7777!

I'm getting WRNN reasonably reliably from my attic-mounted "old" 4228 antenna: http://www.tvfool.com/?option=com_wr...f1f0b6314f3dbb. Never even got a sniff with the 7777.

Also seems to be handling overload better (not perfect) from WEDW, but at < 3 miles from transmitter, and above transmitter ground level, that's to be expected.

For ~$20, I'm impressed! The housing is cheapo, but this is attic-mounted, so not really a concern.
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post #127 of 132 Old 03-13-2015, 09:48 AM
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Quote:
Originally Posted by hancox View Post
FWIW, the RCA is giving me significantly better results than my "old" 7777!

I'm getting WRNN reasonably reliably from my attic-mounted "old" 4228 antenna: http://www.tvfool.com/?option=com_wr...f1f0b6314f3dbb. Never even got a sniff with the 7777.

Also seems to be handling overload better (not perfect) from WEDW, but at < 3 miles from transmitter, and above transmitter ground level, that's to be expected.

For ~$20, I'm impressed! The housing is cheapo, but this is attic-mounted, so not really a concern.
I am impressed as well. I have it hooked up to my set up, and I am 8.9 miles from the transmitters in town. We like to watch out of market channels because they have different sub channels. Also, we can get CBC (and even French CBC!) from time to time so we get some non-American programming. Those transmitters are very weak and 80-100 miles away. Of course, much of that distance is over open water.
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post #128 of 132 Old 03-18-2015, 04:33 AM
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I'm using an original version of the CM7777. I have an RCA ANT751 installed on the roof. I always got excellent results and the amp really helped with my weaker stations. Lately I've been losing 3 of my weaker channels that were always very consistent. Here's my question: Can these amps lose efficiency and be weaker over time or is it an "all or nothing" situation?
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post #129 of 132 Old 03-18-2015, 07:07 AM
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Quote:
Originally Posted by JoeWS View Post
I'm using an original version of the CM7777. I have an RCA ANT751 installed on the roof. I always got excellent results and the amp really helped with my weaker stations. Lately I've been losing 3 of my weaker channels that were always very consistent. Here's my question: Can these amps lose efficiency and be weaker over time or is it an "all or nothing" situation?

They don't gradually degrade over time. It's possible, although rare to have a partial failure. I had a Winegard HDP269 where the gain dropped to 2 dB and the noise figure went up to 10 dB. I think a nearby lightning strike partially zapped it. Unless you have a way to test it, the only way to find out is to replace it. If the problem has slowly gotten worse it could be trees that have grown over time.
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post #130 of 132 Old 03-28-2015, 01:44 PM
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Is there a way to tell when loss of a particular channel is due to the pre-amp causing overload? Do you get the "No Signal" message" or some other indication?
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post #131 of 132 Old 03-28-2015, 04:47 PM
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The tuner can't tell the difference between the decodability of a distorted signal due to overload or from a weak or multipath-impaired signal beyond a certain point. All it knows is that it cannot make heads or tails out of it. After that, it depends on the tuner's manufacturer as to what happens next.
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post #132 of 132 Old 03-28-2015, 06:20 PM
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Overload, a signal that is too weak, a high noise level that reduces SNR, and multipath reflections call all cause an increase in errors.

It is the job of the FEC (Forward Error Correction) to correct those errors, but its ability is limited. Once that limit is exceeded the signal can no longer be decoded. You then have reached the "Digital Cliff" where bad things happen, like pixelation, picture freeze, and finally dropout

It is called the Digital Cliff because the loss of signal is rather sudden as compared to analog signals that slowly get more snowy as they weaken.

Interestingly, if it weren't for the FEC, the digital signal would also degrade slowly as it weakens. It is the FEC limit that causes the sudden loss.



If you can not measure it, you can not improve it.
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Last edited by rabbit73; 03-28-2015 at 06:26 PM.
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