# Help Choosing pre amp for attic OTA



## mattw (Sep 28, 2006)

I currently have a VHF/UHF antenna and pre-amp in the attic that I picked up at Radio Shack a few years ago. The antenna is their "90 mile" version and all the towers are in the same direction 20 -25 miles away. Unplugging the PI I get very little signal. I added the pre-amp mostly to overcome line loss but also because of the attic mount. I currently have approx 80' of RG 6 and two splitters (one a three way) between my HR20 and TV's (both of which have an ATSC tunner). It has been working fine although the signal is a little low on the TV since I gave the HR20 preference on the split (I used the -3 db connection for the HR20 and the -7db output of the splitter for the TV. 

I believe the preamp is starting to die on me and I was looking to upgrade with a new pre amp from solid signal, either a winegard or channel master. I was looking at a CM 7777 but unsure of the winegard options. The web site says to not use the high gain amps less than 30 miles from the towers, does the attic meet that criteria when I'm 20 - 25 away? Would the 16 - 19 db or 23 -26 db gain be "better" would the higher gain just blow out the signal too much? I looked around online and I can't find the gain for the Rat Shack pre amp. My guess is that it is probably around 10 - 15 db gain with fairly high s/n ratio. 

Any thoughts guidance would be appreciated. I hate to buy something like this then have it not work and be difficult to return. I've tried a number of (inexpensive) distribution amps along the way but they actually decreased my readings. I assume that being cheap the s/n the introduced was worse than the additional loss from splitters.


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## veryoldschool (Dec 10, 2006)

While the RS antennas are no problem, their pre-amps [that I've seen] have 10 dB of either gain or noise.
I have the "lesser" Winegard pre-amp which runs through 100', where I then just use a RS distribution amp and four-way splitter.
Noise figure mostly comes from the first amp, so that's where to get a good one.
A large antenna is good "to get" the signal, but adding too much gain later in the feed can't make up for it not getting to the antenna in the first place.
I wouldn't worry about something spec'd above 30 miles open air verse 20 mile under a roof.
The HR-20 doesn't have the greatest OTA tuner and hasan has done a lot of work on his to find the "sweet spot". One of the first things is to use a variable RF attenuator.
So I think you're going down the right path and maybe would add a [cheap] attenuator to you list.


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## mattw (Sep 28, 2006)

Thanks, I went ahead with the CM 7777 and added a $12 attenuator. Soon it will be time to climb in the attic to replace the amp. :flaiming


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## racermurray (Mar 21, 2007)

attenuator ?

I never thought of that , where is the best spot for one - at the antenna or the output of the pre-amp?

Thanks,
Murray


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## mattw (Sep 28, 2006)

racermurray said:


> attenuator ?
> 
> I never thought of that , where is the best spot for one - at the antenna or the output of the pre-amp?
> 
> ...


Given that the antenna and the pre-amp are in the attic, I'm planning on putting the attenuator (if needed) in the garage where all the lines for the house terminate. That way I can get to it easily before it's run out to the tv locations.


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## kenglish (Oct 2, 2004)

You might be overloading the preamp...in which case, you'd need to put the attenuator in the attic.

Time to invent a remote controlled attenuator, I guess.


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## sattec (May 28, 2004)

mattw said:


> Given that the antenna and the pre-amp are in the attic, I'm planning on putting the attenuator (if needed) in the garage where all the lines for the house terminate. That way I can get to it easily before it's run out to the tv locations.


hey matt!..I did a house not long ago and the roof was totally metal and all the support members for roof were metal, the p-amp could not handle the heat in the attic, it freaked out within three days. Temp ranged from 65 at dawn to 130 plus in the heat of the day. I had to pull everything down to a wall plate, hide the amp/spiltter in the wall and go back into attic. I had to bring the 4-way(diode steered) splitter down ...it was getting to hot! just a thought ! (heat injects noise= grainy picture


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## Jim5506 (Jun 7, 2004)

Who would put an antenna in an attic under a metal roof. That's asking for no reception anyway.


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