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Discussion Starter · #1 ·
I'm sure this has been asked before, but a quick search was no help.


Just finished putting Terk 36 up in attic and am finally geting close to getting OTA HD.


In my area, only 1 channel (NBC) is vhf. Don't care much about NBC (no NFL). But if course, it comes in just fine.


I need more gain to pick up some of the UHF signals, particularly CBS (Yeah the Super bowl:) )


I think my best option may be to add an additional UHF antenna and combine it with the aforementioned VHF/UHF antenna. If this is possible, it would allow two angles as just a few degrees between stations is all it takes to lose signal in my location. Don't think I need to go the rotator route, as there is only 5 degrees difference between towers here.


Any how to advice (Just jumper wire lug to lug?).


Am I on the right track? Any advice is much appreciated.


Do not have room for a larger antenna in attic.

Prefer not to roof mount.

Am using a 10db amp for 100' rg6 run
 

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Get a UHF antenna, suitable for your area (see the local info & reception threads).

Replace your your existing 10db amp with a Channel Master CM 7777 V/U preamp .

Open the preamp case (4 screws) and change the antenna input from "Combined" to "Separate".

Connect the UHF antenna to the UHF input and the VHF antenna to the VHF input.


The instructions that come with the preamp explain this....
 

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Discussion Starter · #3 ·
Thanks for the tip. Looks like the way to go.


One thing that may be an issue. Would running a separate feed to the amp kill off the UHF signal from the UHF/VHF antenna. I think I'll need UHF signals from both the combo antenna, and the second UHF antenna so I can point each slightly differently. Or will the amp recommended still pass through the UHF signal from both antenna?
 

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Discussion Starter · #5 ·
Hmmm,


Plan B then.. Bought a radio shack UHf antenna. Instructions say to run 300ohm lead from lugs to lugs, (UHF to COMBO), then 75 ohm out from combo antenna.


Guess I'll try this config.


Has anyone out there had success combining antennas?
 

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Quote:
Originally posted by Don Rombach
Hmmm,


Plan B then.. Bought a radio shack UHf antenna. Instructions say to run 300ohm lead from lugs to lugs, (UHF to COMBO), then 75 ohm out from combo antenna.


Guess I'll try this config.


Has anyone out there had success combining antennas?
First off, remove the 300 Ohm twin lead and use a $2 transformer to modify it as shown here .


I use one of those to recieve channels from Toledo. My main antenna is a rooftop for Detroit stations. I use a standard radioshack splitter/combiner to combine the two OTA signals to feed into the Dish 811's 8VSb module. This works wonderfully. Good luck.
 

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shankar,

You are lucky. Combining two UHF (or two VHF) in different directions is a crap shoot, at best. In some cases it will not work, or only work intermittently, depending on the weather, time of year, etc.


For stations (all UHF or all VHF) in two different directions that can't be received with one stationary antenna, it's usually best to use a rotor, or use two stationary antennas and an A/B switch to change antennas.
 

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Quote:
Originally posted by arxaw
shankar,

You are lucky. Combining two UHF (or two VHF) in different directions is a crap shoot, at best. In some cases it will not work, or only work intermittently, depending on the weather, time of year, etc.
I indeed am! Especially, considering the fact that the RS Double bow tie, now replaced with the silver sensor in indoors, in the basement! I can even pick up the Lansing CBS channel WLNS, more than 60 miles away!


BTW, why do you say that combining 2 UHF antennae won't work??
 

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The reason that it usually doesn't work is that the two signals, not perfectly in phase, combine to create ghost images which digital (ATSC) receivers find very hard to handle. ARXAW had good advice. Get a decent UHF antenna such as the channel master 4228.
 

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Quote:
Originally posted by shankar
... BTW, why do you say that combining 2 UHF antennae won't work??
It will work in some cases, as you have found. But it will not work well in cases where both antennas are picking up the same channel, but one is receiving the main signal and the other one is receiving a "bounce" or multipath signal.


In the analog world, multipath signals arriving at the tuner at slightly different times cause ghosting or multiple images. In the current 8VSB digital world, multipath will often kill a digital signal. This may change when better receiver chips are developed that actually use multipath signals to their advantage. The LINX chip is one that may solve this problem. It has already been licensed by Thomson and others for use in new OTA receivers.
 

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Unfortunately, the Linx chip does not yet exist. Linx has promised delivery of samples in the second quarter of 2004. I, and I'm sure many others, hope that they succeed.
 

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Quote:
Originally posted by ClarkeR
... Linx has promised delivery of samples in the second quarter of 2004. I, and I'm sure many others, hope that they succeed.
I was told by someone at Thomson (RCA) that they hope to have LINX technology in STBs and integrated sets, possibly as early as '05. The technology would be very popular here in multipath hell, with stations in several directions .
 

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Quote:
Originally posted by arxaw
shankar,

You are lucky. Combining two UHF (or two VHF) in different directions is a crap shoot, at best. In some cases it will not work, or only work intermittently, depending on the weather, time of year, etc.


For stations (all UHF or all VHF) in two different directions that can't be received with one stationary antenna, it's usually best to use a rotor, or use two stationary antennas and an A/B switch to change antennas.
I have 2 UHF antennas pointed 120 degress of each other hooked to a $3 RS splitter/combiner. Works great for stations in 2 different markets.
 

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Quote:
Originally posted by sdf777
I have 2 UHF antennas pointed 120 degress of each other hooked to a $3 RS splitter/combiner. Works great for stations in 2 different markets.
YMMV....
 

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I would so much rather have two UHF antennas than a rotor. I only have two directions I need so it would be great if I could just use a combiner.
 

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I am not sure about everyone else but for me the reason I want to combine signals is to get out of the hassle of if I want to record to VCR/DVD or whatever and the signal is from different directions I don't have to *remember* to rotate the antenna.


JM2C


T
 

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Quote:
Originally posted by Don Rombach



... snippage ... Don't think I need to go the rotator route, as there is only 5 degrees difference between towers here.


Any how to advice (Just jumper wire lug to lug?).


Am I on the right track? Any advice is much appreciated.


Do not have room for a larger antenna in attic.

Prefer not to roof mount.

Am using a 10db amp for 100' rg6 run
With only 5 degrees or so between the towers, your best bet might be the channel master 4 bay or 8 (4228) bay antenna. Either of these will give you substantially more gain than that Terk piece. Perhaps more importantly in your case is the smothness of the directional pattern that the CM antennas offer. This should probably work without requiring any rotation.


Combined VHF/UHF antennas frequently have a lot nasty sidelobes in the UHF patterns owing to the off-axis characteristics of the VHF elements which act as 3/4 wave, 1+1/4 wave and other multiples of UHF frequencies. Thus, such antennas are frequently VERY sensitive to multipath.


Alternately you might try one of the Winegards, take your pick from the 9065, 9085, or 9095 versions. These all of the advantage that the 75 ohm transformer is built into the antenna, eliminating a major source of gain loss in many 300 ohm antennas, i.e. the high VSWR and lossy nature of most matching transformers. The 9095 might be a bit TOO directional for your needs, but it has the largest reflector, which is good - and you can always assemble the antenna without the nose piece, making it effectively into a 9065 with a beefed up reflector = good multipath rejection, but with a broader main lobe and a little less gain ... good for picking up several signals in almost the same direction.
 
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