Uhf Antenna Booster? - AVS Forum
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post #1 of 15 Old 08-25-2008, 08:52 PM - Thread Starter
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I have built the attic uhf coat hanger with covered foil type antenna a few months back and now have it split with a two way cable tv type splitter and it works good with my venturer and zenith dtt901 boxes but i plan on adding another cecb and a new hdtv soon so i will need to ungrade to a four way splitter,i would like to know if i will get a large enough signal loss so that i would have to use an amplified antenna booster but what kind will work best for my setup?,i have the cable tv type vhf amplified antenna booster but i'am not sure how that will work,i have not seen any type of uhf amplified antenna boosters,can anyone tell me where i can get one?
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post #2 of 15 Old 08-25-2008, 09:12 PM
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Any 10 dB Distribution Amp (DA) should work. Make sure you put it before the splitter. The 10 dB output will be more than enough to overcome the 7.0 dB loss through the splitter.
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post #3 of 15 Old 08-25-2008, 09:13 PM
 
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Quote:
Originally Posted by video45 View Post

I have built the attic uhf coat hanger with covered foil type antenna a few months back and now have it split with a two way cable tv type splitter and it works good with my venturer and zenith dtt901 boxes but i plan on adding another cecb and a new hdtv soon so i will need to ungrade to a four way splitter,i would like to know if i will get a large enough signal loss so that i would have to use an amplified antenna booster but what kind will work best for my setup?,i have the cable tv type vhf amplified antenna booster but i'am not sure how that will work,i have not seen any type of uhf amplified antenna boosters,can anyone tell me where i can get one?


You'll need an amplifier that's designed for both UHF and VHF (as some channels will be reverting back to VHF next February). A VHF only amplifier would be useless for these type of signals, as most are (and will continue to be) UHF.

A good (and inexpensive) choice is the "Pico/Macom" model TA-25.
It's an 18-25db amp which is solidly built and reliable. It's also inexpensive (as compared to other amps that won't neccessarily work better).

It's available from Parts Express (in Ohio). Their part number is #180-470.
The price is $22.66. They're a reliable, credible source on the web.
Their phone number is: 1-800-338-0531.

Here's the link:

http://www.partsexpress.com/pe/pshow...TOKEN=79941628
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post #4 of 15 Old 08-25-2008, 09:20 PM
 
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Quote:
Originally Posted by systems2000 View Post

Any 10 dB Distribution Amp (DA) should work. Make sure you put it before the splitter. The 10 dB output will be more than enough to overcome the 7.0 dB loss through the splitter.

Be aware that a 10db amplifier can often provide little benefit (especially when a signal is being split 3-4 ways or is somewhat weak to begin with).
The 18-25db amp (I described above) is generally more effective (and can actually cost less than a 10db amp!).
If (in some cases) the db level is too high, you can always use an attenuator to trim it.

......With a 10db amp, you're limiting your options.
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post #5 of 15 Old 08-26-2008, 07:01 PM
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Originally Posted by slprp1 View Post

Be aware that a 10db amplifier can often provide little benefit (especially when a signal is being split 3-4 ways or is somewhat weak to begin with).

The 4-way splitter has a loss of 7dB. The DA has a gain of 10dB. That is more than enough to negate the splitter (and then some).

Overdriving the receiver/tuner doesn't help a thing. Many higher gain amps will insert more noise and have a higher "Noise Figure."

If the signal is weak, then a low noise pre-amplifier (that does not have a higher gain than the input maximum to the DA) needs to be installed.

NOTE: If there is a choice, get the unit that has a FM In/Out switch and place it in the On position.
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post #6 of 15 Old 08-26-2008, 09:53 PM - Thread Starter
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I found a 4 way vhf/fm 10db amplified booster i had in storage and it worked out good with my venturer and zenith dtt901 boxes,i got a stronger signal reading on some of my weak channels and i can see no negitive effects from the boosted signal but i'm only using two of the outputs right now and plan on using all four outputs in the near future,will all four outputs have a 10db boost or would it be devided by 4(2.5db per output)?
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post #7 of 15 Old 08-27-2008, 02:04 AM
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screw terminating resistor plugs into those other two ports if you won't be using them.

They LOOK like this.

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post #8 of 15 Old 08-27-2008, 08:20 AM
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Quote:
Originally Posted by video45 View Post

I found a 4 way vhf/fm 10db amplified booster i had in storage and it worked out good with my venturer and zenith dtt901 boxes,i got a stronger signal reading on some of my weak channels and i can see no negitive effects from the boosted signal but i'm only using two of the outputs right now and plan on using all four outputs in the near future,will all four outputs have a 10db boost or would it be devided by 4(2.5db per output)?

It's a 10dB amplifier followed by a 4-way splitter (which typically is 7dB down on each output), for about 3dB of net gain per output. That this is near 10/4 is only coincidental.
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post #9 of 15 Old 08-27-2008, 06:40 PM
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Quote:
Originally Posted by video45 View Post

I found a 4 way vhf/fm 10db amplified booster i had in storage

Is this what you have? http://www.summitsource.com/4-way-vi...16-p-6825.html

If so, that DA doesn't support UHF frequencies (470-806 MHz), which most digital stations are on currently. You need to get something that supports both VHF & UHF, like the Eagle Aspen 15dB Off-air/CATV Distribution Amplifier (DISTAMP-15GX) with 4.0dB Noise Figure (4.0 or below is preferable) for $ 13.99 at Solid Signal.
http://www.solidsignal.tv/cat_displa...CAT=Amplifiers

The 15 dB gain of the Eagle Aspen DA will produce a 8 dB gain on all outputs of the 4-way splitter. and will be less expensive than purchasing a 4-port DA.

Quote:
Originally Posted by video45 View Post

...i'm only using two of the outputs right now and plan on using all four outputs in the near future...

As mentioned in the previous post, get a couple of 75 Ohm terminators for the two unused ports. This will eliminate reflections in the cable that will degrade the quality level.
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post #10 of 15 Old 08-28-2008, 08:39 AM - Thread Starter
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No,it is a gemmeni(i sorry if i misspelled the brand name) model 32121,50-450mhz 4 output amplified type booster,i'am not using an additional 4 way splitter with the booster.
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post #11 of 15 Old 08-28-2008, 08:45 AM - Thread Starter
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I know your right about using the eagle aspen UHF/VHF booster but my 4 output 50-450mhz booster seems to work out good with no negitive effects on the video quality that i can see.
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post #12 of 15 Old 08-28-2008, 09:45 PM
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Quote:
Originally Posted by video45 View Post

No,it is a gemmeni(i sorry if i misspelled the brand name) model 32121,50-450mhz 4 output amplified type booster,i'am not using an additional 4 way splitter with the booster.

50-450 MHz is in the VHF range (2-13) and really should be replaced, so that you don't have a future problem with the lack of support for the UHF digital stations (14-51).
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post #13 of 15 Old 08-29-2008, 12:50 AM
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Quote:
Originally Posted by video45 View Post

I have built the attic uhf coat hanger with covered foil type antenna a few months back and now have it split with a two way cable tv type splitter and it works good with my venturer and zenith dtt901 boxes but i plan on adding another cecb and a new hdtv soon so i will need to ungrade to a four way splitter,i would like to know if i will get a large enough signal loss so that i would have to use an amplified antenna booster but what kind will work best for my setup?,i have the cable tv type vhf amplified antenna booster but i'am not sure how that will work,i have not seen any type of uhf amplified antenna boosters,can anyone tell me where i can get one?

These are really reception-related issues and it would be more appropriate to discuss them over in the main, Technical area.

(Mods - maybe move it if you think?)
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post #14 of 15 Old 09-03-2008, 02:05 PM
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Quote:
Originally Posted by video45 View Post

I know your right about using the eagle aspen UHF/VHF booster but my 4 output 50-450mhz booster seems to work out good with no negitive effects on the video quality that i can see.

The UHF band you need to amplify for DTV is about 450MHz to 900MHz.

BTW: each 2-1 spilt drops the signal by 6 dB (Voltage). If you split each of those two down to get four lines, each will be about 12 dB (Voltage) down from the original signal level.

If the gain specs are in power (not voltage) divide all dB readings by 2.
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post #15 of 15 Old 09-04-2008, 02:49 PM
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Quote:
Originally Posted by bountyh View Post

The UHF band you need to amplify for DTV is about 450MHz to 900MHz.

The actual range of UHF (14 to 51) DTV will be 470MHz to 698MHz.

Quote:
Originally Posted by bountyh View Post

BTW: each 2-1 spilt drops the signal by 6 dB (Voltage). If you split each of those two down to get four lines, each will be about 12 dB (Voltage) down from the original signal level.

If the gain specs are in power (not voltage) divide all dB readings by 2.

Most splitters that have loss numbers on them, specify a 3.5dB loss. In reality:
Quote:


The loss in a good splitter is around 4.0 dB per split. An average splitter has around 4.5 dB loss per split.

http://www.hometech.com/video/splitters.html
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