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Old 29-Jan-2013, 11:47 AM   #1
chiefgeek
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Help with Amp/pre-amp ...

Here is my signal analysis

I have an RCA ANT751R on the roof (single story). I had it hooked up to a CM-7777 (old style with sep vhf/uhf inputs ) and the cm-7777 was blocking wfaa 8.1 (vhf 8).

With no pre-amp I am getting about 95-100% signal strength on 4.1, 5.1, 8.1, and 11.1 (all that I care about). I would like to split the signal 6-8 ways.

What amp/pre-amp do you recommend.
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Old 29-Jan-2013, 11:59 AM   #2
No static at all
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Do you have the switch inside the 7777 set to combine? Is the FM trap set to IN? If these suggestions do not solve your problem, you would be better served with a distribution amp rather than a pre-amp. I recommend the Channel Master 3418 for your needs.
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Old 29-Jan-2013, 3:08 PM   #3
teleview
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First.

To , Prove Reception.

Run a -->New<-- loooong coax from the antenna through a open window or door direct to 1 Tv.

No amplifiers , No amplifier power supply or power injector , No splitters , No couplers , No nothing.

Aim the ANT751 antenna at about 205 degree magnetic compass direction.

Here is how to aim antennas , http://www.kyes.com/antenna/pointing/pointing.html.

As always , trees and tree leaves do a good job of , reflecting , reducing , blocking , Digital Tv reception , and so do buildings and other obstructions including your own roof and house.

It is best to install the ANT751 antenna at a location that has the least amount to no amount of obstructions of any type or kind in the direction of reception including your own roof and house.

The signal strengths are strong.

Remove the CM7777 preamplifier , the preamp power injector , the preamp power supply.

Try reception with passive splitters.

And install a , 6 way splitter for 6 Tv's connected.

Or a 8 way splitter for , 7 or 8 , Tv's connected.

-->If<- required , use a Channel Master CM3418 distribution amplifier.

___________________

Coax cables are Always Suspect of being Bad.

Amplifiers are not a substitute or replacement for bad coax and bad coax connections.

Amplifiers will not make bad coax or bad connections , good.

Last edited by teleview; 31-Jan-2013 at 3:33 PM.
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Old 30-Jan-2013, 7:04 PM   #4
chiefgeek
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Quote:
Originally Posted by No static at all View Post
Do you have the switch inside the 7777 set to combine? Is the FM trap set to IN? If these suggestions do not solve your problem, you would be better served with a distribution amp rather than a pre-amp. I recommend the Channel Master 3418 for your needs.
Combine yes
FM Trap IN

I tried putting FM Trap to OUT and I get some signal on wfaa 8.1 (vhf 8) but not enough to be useful.

Thanks for the recommendation, I will give it a try.
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Old 2-Feb-2013, 7:14 PM   #5
chiefgeek
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I went with the CM 3418 and all seems good. I am seeing 85% signal strength for 4,5,8,and 11.
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Old 3-Feb-2013, 2:29 AM   #6
No static at all
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Great news!!! I have become more of a distribution amp advocate after years of thinking pre-amps were the end all. 50-75 feet of coax before amplification is not a deal breaker in most cases.

It's also nice to have the amp inside where it can be easily bypassed during power failures so a laptop or portable TV can be used to watch newscasts during emergencies.
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Old 3-Feb-2013, 6:32 AM   #7
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I have also found the CM341X amplifiers to be very capable when faced with many strong signals. The noise figure is not as good as several of the preamps on the market, but in this case, the amplifier's 1 to 2 dB poorer NF is not going to be an issue and the 2 or 3 dB additional loss in the down-lead can be tolerated as well.

I think the bottom line is, the CM-7777 is a 'fringe' to 'deep fringe' preamp. Your TVFR indicates many strong and medium strength signals which were adding up to overload the CM-7777. While a high input preamp such as the CPA-19, HDP-269 or CM-7778 may also work well, I agree with NSAA that the ease of access makes the CM-3418 a very good choice.
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