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Old 06-24-2009, 07:41 PM   #1 (permalink)
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Default When do phasing problems come into play when using a splitter combiner for antennas?

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Originally Posted by Piggie View Post

2) A combiner while normally used to split a signal for 2 TVs, can be used backwards to combine two antennas. If the antenna are the same band or share a band (one VHF and one a combo for example) it's best to have the coax coming from each the same length where they meet at the combiner.

You can combine just about any two antennas with a splitter combiner, but know you suffer a 3.5 db loss from each antenna compared to being used alone. For example you can have one UHF pointed at one town and another UHF pointed at another town. If loosing 3.5 db is not critical, it can save using a rotor.

Now there is one special case of using a splitter combiner. Stacking identical antennas in the same direction with proper spacing for more gain. In this case both antennas have to identical and the coax from each to the combiner must be exactly the same length and made from the same piece of coax. Then the combiner only adds about 0.5 db of loss combining the antennas. Why this is true gets into how waves travel through the coax and beyond the scope of this review.
Piggie or anyone, when do phasing problems come into play when using a splitter combiner for antennas? Is it when both antennas have a pre-amp.
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Old 06-24-2009, 08:14 PM   #2 (permalink)
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Originally Posted by O-O View Post
Piggie or anyone, when do phasing problems come into play when using a splitter combiner for antennas? Is it when both antennas have a pre-amp.
There are a lot of places you can boo boo and run into trouble with splitter combiner.

Most of them don't involve a pre-amp.

One is when stacking antenna to combine a VHF and a UHF antenna in fringe conditions, when for $10 you can use a UVSJ and gain 3db, or the equivalent of doubling the length of the boom or elements of both antennas.

When you don't use the same length coax cut from the same piece when stacking two identical antennas to increase gain.

Pointing two antenna on the same band in different directions to remove the need for a rotor but by pure chance aiming on into a reflection of a station the other antenna is trying to receive (mega mulit path). It's trial and error anytime you combine two antennas on the same band that you are not trying to stack.

There are mistakes on where to place an amp in a combined system, which I plan to cover in another thread.

Did I even answer your question? If you have a specific situation let me know.
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Old 06-27-2009, 09:45 PM   #3 (permalink)
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Feeding two antennas directly into a splitter/combiner doesn't make any...EDIT: BANNED FOR COPY/PASTE FROM: electro-tech-online.com

The problem begins ...

The amount of ...

So the noise.....

The effect of putting.....

Last edited by Jay; 06-28-2009 at 12:16 AM. Reason: Copy/Paste of article written from another website
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