Piggie

UVSJ vs Combiner/Splitters for Combining Antennas

Note, I am not covering how to stack antennas in this thread, just how to use the combining hardware.

First what are they?
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UVSJ is a small device to combine a UHF antenna to a VHF antenna. It can also be run backwards to separate signals from a combo antenna into a device that requires separate UHF and VHF inputs (rare these days).
Hence the device is mainly used to combine a UHF antenna to a VHF antenna.

Pico Macom UVSJ UHF VHF Band Separator/Combiner for Antenna (UVSJ) | UVSJ [Pico Macom]
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A splitter combiner is just what you use to split the signal to two TV sets, but it can be run backwards to combine two antennas also. You find them in two basic configurations. Ones the look just like the UVSJ above.

These are a dime a dozen so I didn't add a link. If you use one to combine antennas, consider the money you have in the antenna and buy a good one meant to combine antennas.
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And ones made for mounting on a mast. These are excellent for stacking two antennas because they are designed to mount outdoors.

Winegard CC 7870 2-Way Antenna Joiner Coupler (CC7870) | CC-7870 [Winegard]

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Which should I use in my system?

1) Well the UVSJ might be obvious from above. Lets say already owned a UHF antenna and one of your stations switched to VHF. You could go buy a combo antenna or just buy a separate VHF antenna and a UVSJ. Labeled on the device is a UHF port and a VHF port. You simply put the corresponding antenna into the corresponding port and run the common to the TV. One beauty of UVSJ is it has much lower loss (about 0.5db) than a simple combiner reviewed below.

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

Being the scope of this thread was solely designed to inform users about the differences in UVSJ and a Combiner. All questions about phasing antennas, stacking antennas or just combining antennas I am moving to their very own personal thread! Which will all be under DTV Reception.
http://www.dtvusaforum.com/dtv-reception/