Antenna Question

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lowermontcoff

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I have this antenna on my roof and I was wondering if it is for tv only, or can I use it for my scanner? I have psr800 scanner.

I was thinking of putting a st2 antenna in its place but i have a good amount of trees around my house that would be above the antenna. I'm curious if I did buy the st2, would I be wasting my time? Any help would great.
 

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n5ims

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You could use it for your scanner, but there are some issues doing that. First, it's a directional antenna so you'll only get good signals from the direction it's pointing. Second, it's a horizontal antenna and most of what scanners pick up are vertical so there's quite a bit of loss from that as well. Replacing it with the ST2 should take care of both of those issues. Just make sure that the trees are far enough away from the antenna that they won't touch it even in strong winds. They could damage or destroy the antenna if they're able to beat it up any (same goes for your current antenna so you're probably OK though since it looks to be in decent shape).
 

lowermontcoff

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thanks, the st2 sounds like the better option. I also wanted to know if the trees would reduce the signal.
 

n5ims

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thanks, the st2 sounds like the better option. I also wanted to know if the trees would reduce the signal.
Reduce the signal over what? Anything that blocks the signal's path will reduce the signal (even a bug flying between the transmitter's antenna and the receiver's antenna) the real question is will it matter and if so, what are you prepared to do to compensate for it. Trees that are full of wet leaves will most definitely reduce the signal by some. Will it be enough to matter, perhaps yes, perhaps no. Will the outside antenna with the wet leaves be better than a short radio mounted antenna in your basement, most likely lots better.

If you're really worried about the leaves, you have two options. Mount the antenna on a much taller tower to get it well above the leaves or cut down the trees so they are no longer a factor. Neither are good answers, especially if your signal is good with the trees where they are. Remember that more signal isn't always better. It is quite easy to have too much signal which will result in worse reception instead of better. See the chart below to help explain the too little, just right, and too much signal issue.

Table of signal levels vs. reception quality:

Signal amount (relative number showing 'signal strength') - reception quality
No signal (0) - no reception.
Very little signal (1) - noisy reception.
A little signal (2) - noisy, but understandable reception.
A little more signal (3) - less noisy, but understandable reception.
Just a bit more signal (4) - nearly no noise, good reception.
Descent signal (5) - no noise, good reception.
Strong signal (6) - no noise, great reception.
Very strong signal (7) - no noise, great reception.
Super strong signal (8) - no noise, great reception.
Overly strong signal (9) - possible noise, understandable reception with some weaker signals wiped out by overloaded circuits.
Too much signal (10) - noise, interference, intermod, phantom signals, weak and moderate signals wiped out by overloaded circuits.

As you can tell, you're in pretty good shape if your signal is in the middle 60% of that range. Too little signal and you have noisy (at best) reception. Too much and you have the strong signals overloading the circuitry, causing the weaker signals to be lost. In the middle range you have enough signal to give you good reception and not enough to overload the circuits.

One other point I feel is necessary to make is it isn't just about the antenna, it's about the antenna system (antenna, tower/mast, feed line/coax, location, accessories) as a whole. A great antenna that's too low won't work well. A great antenna at a fantastic height and perfect location but using cheap coax won't work well. Location, while important, may be what you've got more than what you want. Sure, it would be fantastic if it had a perfect view, but most don't (like you and your trees). Accessories are things like preamps, filters, etc. that help to boost/filter/reduce the signals to correct for imperfections. Avoid them if you can (they always cause some undesired problems) but use them if you must.
 

12dbsinad

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Good advise from n5ims. The front end (reciever) on most scanners can be easily "overloaded" when connected to an external antenna. Your location also plays a big part in it as well. If you live in a city for example around all sorts of RF, it would be even worse than living in the country away from lots of other RF. This is the fine line depending on your location on what type of antenna you can hook up to your scanner.

For example, I have a friend who wanted to extend his reach hearing a VHF P25 radio system used statewide. He put up a commercial VHF base station antenna on his roof that he got offline. The antenna is about 10 feet tall and has "gain" on the VHF band. The end result was, he couldnt hear anything worth of beans. This was because the gain of the antenna on VHF was to much for what his scanner could handle, giving his location in-city, and was severly overloading the reciever of his scanner. The fix to this was intalling a zero gain antenna (much smaller) and all of a sudden his scanner sprung to life.

For the heck of it, try hooking up your scanner with the TV antenna. Its already there, and isn't going to hurt anything. You might even find it works pretty good even being directional. If not, then you can always replace it!
 
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