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Old 22-Nov-2012, 1:38 PM   #1
MrNewo
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Pre-amp AND distribution amp?

I've installed a Clearstream 2V in my attic. I took a TV up there and saw a great picture on most channels. A few more were found, but are marginal and unwatchable. The ones I get are just barely in the green on the digital converter box's signal strength "meter"... I figure probably about 70% of full potential. Roof mounting isn't gonna happen without hiring someone else to do it. It's 40' above the ground and a steep roof pitch.

I installed 100' of RG6 to the house's pre-wired junction box which probably takes RG59 from there to each room another 75' or so.

Should I get an Antennas Direct CPA19 pre-amp, install it in the attic and limit my splits in the box to a digital 4-way splitter to serve 4 TVs? OR would I need to install a distribution amp at that point?

Here's my plot:
http://www.tvfool.com/?option=com_wr...cc4905f6e15213

I'd love to get all signals in the yellow section.

Thanks in advance!
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Old 22-Nov-2012, 4:29 PM   #2
teleview
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Attics Are Not a reception friendly environment and Never Will be a reception friendly environment.

Attics are a - Close In - reception environment that produces close in signals bouncing all around in the attic known as - multipath.

Multipath is not reception friendly in the attic.

Attics reduce signal strength.

The following is non complete list of situations that , reflect , reduce , block Tv reception in the attic.
Metal in the attic such as HVAC units and ducting , nails , the flat metal pieces that hold the roof beams together , metal roof , concrete or adobe roof tiles , wood construction of the attic.

Can reliable reception happen in the attic??

Yes it can , however does not mean that attics are a reception friendly environment.
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I recommend install the CS2V antenna above the roof in such a manner that roof or house is not reducing or blocking reception to the , north , east , south east.

Aim the CS2V antenna at about 130 degree magnetic compass direction.

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

For 1 Tv connected use no splitter. No amplifier.

For 2 Tv's connected use a Channel Master CM3412 distribution amplifier.

For 3 or 4 Tv's connected use a CM3414 distribution amplifier.

_____________________________________________________

Here are some above the roof antenna mounts , http://www.ronard.com/909911.html , http://www.ronard.com/34424560.html , http://www.ronard.com/ychim.html , http://www.ronard.com.

Buy the ronard antenna mounts at solidsignal by typing the word ronard in the solidsignal search box.

Here are some places to buy antennas and etc. , http://www.solidsignal.com , http://www.amazon.com , http://www.channelmasterstore.com.
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As always , trees and tree leaves do a real fine job of reducing or blocking Tv reception and so do buildings and other obstructions including your own house.

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

The Tv/s Must Channel Scan for the Broadcast Tv Channels , sometimes named the 'Air Channels' or 'Antenna Channels' in the Tv setup menu because the Tv transmissions travel through the air from the transmitting antenna to the receiving antenna.

DO NOT channel scan for cable tv channels.
______________________

Digital Tv tuners can develop - Digital Glitches - that are not cleared out with a simple channel scan .

I recommend do a Double Rescan of Broadcast Tv Channels .

http://www.dtv.gov/rescan.html

Last edited by teleview; 6-Dec-2012 at 8:43 AM.
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Old 22-Nov-2012, 8:25 PM   #3
GroundUrMast
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If you can't see the stations you want with the antenna connected to one TV using a short cable, it's unlikely a preamp will help. (If the tuner has a poor noise figure one may see some improvement.)

To see more stations, more reliably, the existing antenna needs to be mounted in a more favorable location or you need 'more' antenna. At this point, the least expensive option would be to try different locations in the attic. Also, considering that the C2V is a compact antenna, you may be able to find a wall mount location that works well.

Once you have usable signals at the antenna, then a use a preamp to overcome the losses from cable and splitters. A CPA-19 is rated at 17 dB gain. That's nearly equal to the total loss through 175' of coax and a 4-way splitter. I would try the CPA-19 and no DA. A DA can be added latter if the need is proven.

In terms of 'more antenna', look at the path profile of any of the stations on the 133 azimuth (click on the call sign of a station on your TV Fool report). You see a very tall terrain 'feature' 4 to 5 miles away. If I was in your situation, I'd consider going to a 43XG or even a 91XG to get the directivity which would combat the anticipated multipath. To receive the High-VHF signals, I'd use an Antennacraft Y5713 or Y10713. The two antennas serve separate broadcast bands so they are easy to combine using a UHF/VHF Signal Joiner (UVSJ).

I would roof mount. High and clear of obstructions is nearly always better. At 40', I'd have my safety harness on for sure.
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Old 3-Dec-2012, 4:32 PM   #4
MrNewo
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Pre-amp AND distribution amp?

Thanks to both for your replies. I had some family issues pull me away from the forum and for some reason, I didn't get any notifications of the replies.

Teleview, I'd love to get an additional 20dB by putting it on the roof. But again, that ain't gonna happen! I will, however, position it to get metal-free paths to the station vectors I need.

GroundUrMast, I jumped the gun to get the CPA19 on sale and hooked it up. At 100' down the line, I get about 20 channels & subs that are usable... not bad! I toyed with the idea of wall mounting the antenna, but I would sacrifice about 10-15' in height to get it outside. Would you think that's a good tradeoff?

I'm inclined to add either a CM3414 (as Teleview recommended) or a Winegard equivalent if I get too much drop through the splitter and remaining 75'. I've heard CM units come from China and the quality may be hit-or-miss. Insights?

Thanks again for your help!
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Old 3-Dec-2012, 6:19 PM   #5
GroundUrMast
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I'm glad to hear the CPA-19 gain was of benefit. That does not change my understanding of the purpose of an amplifier though. The job of any TV preamplifier or distribution amplifier is to overcome the losses in cable, splitters and poor tuner noise figure.

All amplifiers add some noise and distortion to the signal. All amplifiers have some maximum operating level, above which they fail to amplify and only distort.

Rule of thumb: One amplifier can be too many. Two amplifiers are almost always too many.

Having said that, if you want to experiment with the idea that an amplifier can be a substitute for an antenna, you're not likely to break anything trying. I sincerely believe your time and money would be better spent on antenna choice, placement and aim.

Wishing you much success.
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Old 3-Dec-2012, 7:08 PM   #6
MrNewo
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I got the pre-amp before reading your reply. Trying to make the best of what I've got.

I'm taking the advice of some of the resources found on this forum that reinforce what you're saying. But, if I am trying to preserve the best signal I was able to get in the attic, I'm simply amplifying to overcome losses down the line (pre-amp noise, 100' of RG6 loss, distribution amp noise and 75' of RG59 loss). As I understand it, I'm taking the lesser of two evils: either the signal loss of a splitter and RG59 OR the noise inserted by a distribution amp.

Thanks again for all the help!
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Old 3-Dec-2012, 7:58 PM   #7
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There are times where both a pre-amp and a distribution amp are needed. My home is one of those. However, successive stages of amplification may not be desirable as it tends to increase the overall system noise figure. Each circumstance is a bit different.

Applying an amplifier in an attempt to compensate for a poor antenna location or for one with insufficient gain is about as effective as applying a Band-Aid to a sucking chest would - too little, too late. Once signal quality has been lost and the ration of signal to noise gets too low, amplifiers can't fix it. It's the old "garbage in, garbage out" as we all learned in computer classes.

Since all your Atlanta stations are 1- or 2-edge diffraction signals, you will encounter layering of the signals. You may need to experiment with various antenna heights and locations, even within the attic, to see if you can achieve reliable reception.

Good luck!
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Old 4-Dec-2012, 6:28 AM   #8
GroundUrMast
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Channel Master CM-341X DA

My personal experience with the CM-3418 and CM-3410 has been positive. I have no reason to say anything negative about them. I don't own the lab grade equipment needed to measure gain, noise and distortion so I can't confirm or deny the published specifications.
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If the well is dry and you don't see rain on the horizon, you'll need to dig the hole deeper. (If the antenna can't get the job done, an amp won't fix it.)

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