Antenna and amplifier questions... - AVS Forum
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post #1 of 7 Old 07-21-2010, 02:02 PM - Thread Starter
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Been searching for sometime on here and I'm still stuck with a couple questions....

Dropped cable going OTA for now

I picked up a Eagle Aspen Dtv2Buhf Directv 2-Bay Uhf Antenna (similar to DB2 (can't tell any difference 'cept price)) I wanted the one antenna to run both tv's in the house. Upstairs mounted inside in the window I do really good for reception, so what I want to do is connect antenna to the existing cable wiring in house, that goes downstairs to the splitter for the whole house.

I was able to source a 8 output amplifier (Antronix VRA900/ACP) which I believe qualifies for as an amplifier and not a preamplifier.

Currently I get all local channels in decent quality (upstairs) even though I'm some 30 miles south of the major towers in the area, Downstairs with a lesser antenna I have issues with signal quality, constantly adjust antenna to get certain channels, but it seems I can pretty much get them all, (not at the same time).

So I'm trying to figure out if,

1. If I should use the amp and where? Upstairs or downstairs splitting sources... 30'-40' line to downstairs splitter, and two 30' runs out of the splitter back to tv's. All decent quality cable and splitters.

2. How to hook the stupid amp up.... no instructions.... Has separate power source a splitter and the amp itself. I think it's something like power supply to splitter to amp, but then I'm not totally sure if it just goes in the input or the VOIP or Output 1 spot... Then I tie the antenna in the input spot?... I suspect I'll somehow figure this out someday, but I don't want to burn up the amp testing.... See pic

3. Will this work? Any additional comments? I'm a bit curious if the will help me or hurt me, I know too much signal is a problem too. I suppose it's easy enough to test once I figure out the amp.

(Panasonic G15 and Vizio 32inch 1080 Java case it matters...)


Edit: I believe this was the proper forum to post this question. If not mod feel free to move
LL
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post #2 of 7 Old 07-21-2010, 02:36 PM
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While the Antronix amp might work, I don't think that you have the right product for what you need. The writeups that I found for the Antronix talk about an 1125mHz to 1525mHz design. These frequencies are well above the US's highest UHF frequencies.

On the Preamp amp subject. The way that I understand it, most everything that is sold is an amplifier. What we usually call a 'Preamp' is an amp that is moved as close to the antenna as possible so that we amplify with minimum loss of signal level from coax length and splitters. Some outdoor amps ('preamps') are not designed for strong, close-in signals and will overload. Overload causes a poor viewing experience.

The outher type of amp is a distribution amp. This is an indoor, non-weather proof device. These typically will take greater input signal than most preamps. The textbook use for these amps is when the signal is fine for service to a single set but too weak to power multiple sets.
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post #3 of 7 Old 07-21-2010, 03:16 PM - Thread Starter
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Thanks that give me some more search ideas, I'm going to start moving things around see and how things work.
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post #4 of 7 Old 07-21-2010, 08:15 PM - Thread Starter
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WHEW.... That was quite the process, I have reached my goal, all channels on both tv's no issues, one antenna. It took one heck of a trial period to get everything sorted. I'm not sure exactly why, but the Dtv2Buhf is too much antenna, there must be some amplification in the connectors I used, but nothing is powered, all I know is I had too much power to pickup channels. Seriously I'm a good 30 miles from the towers, pretty impressive.

Read plenty before posting, so I'm glad I was aware of the issue of having too powerful of a reception.

I ended up with my "lesser" RCA powered antenna, to the downstairs then split there back to the tv's, certainly not the results I had expected, and I'm a little bummed out about it too, the Dtv2Buhf would've been easier to conceal in the window.


As far as the Antronix VRA900/ACP goes, First off it says it's rated 52-1002 HZ so it certainly does work with the OTA frequencies (as observed), I believe it has potential to work higher up based on what I read, not sure what you'd use that for now. I believe the power goes in the Voip spot, and the antenna goes in the input spot, I ended up figuring that had to be the way it went. Hopefully that helps someone out some day.

And I got all the unmarked cable wires at the splitter marked now

All that said, I actually think it's the best looking quality wise pic we've had yet, the wife seems to agree.



And I promise to stop talking to myself now (unless you end up actually reading this thread and it somehow helps you bump it for me so I know all this talking to myself wasn't a total waste :lol: )
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post #5 of 7 Old 07-25-2010, 07:31 AM
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The Antronix amplifier shown in your post above is a splitter-amplifier, designed to let you split your signal 8-ways with no insertion loss. An 8-way splitter normally has -10.5 db of insertion loss (per port) which indeed is a great deal of loss. In order to negate this loss, the splitter-amplifier has only enough gain (amplification) to offset the loss. Thus it amplifies the signal +10.5 db (approx) but the net gain from the input port to any one of the output ports is zero. Another way to think of it is a "lossless splitter".

In any case, this is not the correct type of amplifier to do what you're wanting to do.

What you need is a "drop amplifier", such as the Motorola 484095-001-00 amplifier http://www.tigerdirect.com/include/A...1000&imgcart=1

This is a great universal 15db amplifier. It's also "duck-soup" simple to hook up.

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post #6 of 7 Old 07-25-2010, 08:37 AM
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Quote:
Originally Posted by Steve_Weggus View Post

What we usually call a 'Preamp' is an amp that is moved as close to the antenna as possible

A "preamp" generally receives its power via the antenna (coax) cable, from a power module that the coax "passes through" inside the house. The power module in turn gets its power from a normal wall outlet. This allows the amplifier module to be mounted outdoors on the antenna mast without having to run a separate power cable.

An "amp" gets its power directly from a wall outlet (possibly via a "wall wart" power supply) and therefore has to be located indoors.

Also, preamps generally have lower noise figures (NF) than amps, which is important because the raw signal at the terminals of an antenna can be much weaker than what you get from a cable-TV feed. With weak signals, you need a good signal-to-noise ratio at the TV in order to get good reception, so the less noise added by the amp/preamp, the better.
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post #7 of 7 Old 07-25-2010, 10:47 PM - Thread Starter
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Quote:
Originally Posted by Cap'n Preshoot View Post

The Antronix amplifier shown in your post above is a splitter-amplifier, designed to let you split your signal 8-ways with no insertion loss. An 8-way splitter normally has -10.5 db of insertion loss (per port) which indeed is a great deal of loss. In order to negate this loss, the splitter-amplifier has only enough gain (amplification) to offset the loss. Thus it amplifies the signal +10.5 db (approx) but the net gain from the input port to any one of the output ports is zero. Another way to think of it is a "lossless splitter".

In any case, this is not the correct type of amplifier to do what you're wanting to do.

What you need is a "drop amplifier", such as the Motorola 484095-001-00 amplifier http://www.tigerdirect.com/include/A...1000&imgcart=1

This is a great universal 15db amplifier. It's also "duck-soup" simple to hook up.

.

I hear what you're saying in practice it didn't work that way, at least not with 1 or two output of of the Antronix, I'm certain it did amplify the signal and my reception problems only got better when I started adding more connectors, thus dropping the db's and the issue was only solved by going to a lesser antenna. I had some wild configurations running trying anything to get this to work, frankly I was a bit shocked it all works perfect on the lesser antenna. Though I have noticed since I last posted that I need to raise and just the antenna again to keep 3 channels we watch a fair bit, in strong signal. The Panasonic seems to be better overall for channel pickup than the Vizio, I guess I wouldn't say it surprises me a whole lot, but interesting none the less.

BTW I got the amp for free when I had to use up some points from Charter's point program, before they went away when I canceled my service. Was the best choice for my points.

Thanks for the product link I may end up going that route yet if I change antenna locations yet again because I'm not overall thrilled with the current location though reception is great.
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