Originally Posted by gfparker
Is it ok to just use a splitter to combine the two antennas? Is the fact that one antenna is UHF/VHF and the second is just UHF causing me problems? The amplifier on the UHF/VHF is an old unit from Home Depot, but the amplifier on the UFH is a newer Winegard amp. Any help anyone can give me would be appreciated.
Yes ... and no
I have some experience here, I tried this almost 2 years ago and then spent the next 8 months learning more about Physics.
The reverse splitter trick technically works, but here's what happens. First off, you're losing >50% of the signal from each source (~3.5dB). Not a big deal if you amplify first and then combine. The more important problem is that if each antenna "sees" the same channel, even if it's via a weak reflection, you end up with multiple standing waves on the line at the same frequency. Unless you're the luckiest person ever, these waves will not be in phase and will cancel each other out to some degree and confuse the receiver. In essence, you're creating multipath. By amplifying the signals before combining them, you're creating some really nasty multipath
Given the description, that's what I think is happening here. Since the UHF-only antenna has no appeciable gain for 7 and 9, all you're losing is 3.5dB at the combiner on those channels. Since it's already been amplified, not a problem. On the UHF side, however, you're playing with fire. Apparently 4 (UHF 48) has it the worst with your setup, but I would bet that given a change in weather/temperature you'd find more and more channels exhibit the same problem, especially as we head into the winter months.
Let me ask you this ... what is your goal? Was it to just get 7 and 9 back? If that is the case, what you want is a VHF/UHF diplexer, not a splitter. Hook the Radio Shack antenna to the VHF side and the UHF antenna to the UHF side .. BEFORE any amplification. A diplexer is an RF filter that can combine the low VHF frequencies with the high UHF frequencies with almost no loss at all, and it has the benefit that any UHF signals picked up on the VHF antenna are completely filtered out for you, and won't cause you any more grief.
Now, be advised, depending on what model # your Winegard amp is (please tell us and we can look it up), it may not be able to amplify VHF. The one from Home Depot is probably not a very good device, I personally don't recommend using it (GE model perhaps?). If the Winegard amp cannot amplify VHF, you can still try it and see what happens, but it's likely you may need an amplifier capable of handling both VHF and UHF.
My personal advise would be to try a VHF/UHF diplexer first (also called a "combiner" if you're Googling or trying radioshack.com), then run the combined signal into the Winegard amp, and see what happens. If it works well, it's a cheap easy solution. If you don't get good results on the VHF side, you probably want/need a different amplifier.