Antennas & Amplifiers

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tomasG

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I live in the desert and wnat to be able to hear more Los Angeles stations. I have read just about all of the messages here and still don't know which is better. I want good performance on all bands including 800mhz. 800 is important to me. I have read mixed comments on the ST-2, the Diamond, a Ferret, and a Radio Shack thingy. It kind of sounds like the ST-2 is the better choice and a friend of mine has the Ferret and says it was a waste of money.

I saw an ad recommending an expensive amplifier with 23db and a discone or a Ferret for excellent performance and this didn't sound right. I asked my uncle, a ham operator, and he said that if you can't hear a signal to begin with you are only amplifying the noise. He said to get a good antenna to start with but doesn't know about scanner ones.

Now I am confused.
 
N

N_Jay

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There is no "best" antenna.
Multi-band and wide-band antennas are compromises.
Amplifiers amplify both the desired signal and everything else (noise)
Amplifiers also add noise.
There are no hard and fast answers as to what you may or may not be able to hear in any particular location.

Less confused?

If it were me, I would start with simple scanner antenna or discone put up as high as I can get it with a run of good quality RG-6.

I might try a good preamp to see if it helps, but that is very hit and miss.

(Might seem like it is helping some stations while completely hiding others.)
 

gmclam

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Welcome to RadioReference.com!

I live in the desert and wnat to be able to hear more Los Angeles stations. I have read just about all of the messages here and still don't know which is better. I want good performance on all bands including 800mhz. 800 is important to me.
If all the signals you want to receive are coming from the same direction, a directional antenna would be a better choice.

I saw an ad recommending an expensive amplifier with 23db and a discone or a Ferret for excellent performance and this didn't sound right. I asked my uncle, a ham operator, and he said that if you can't hear a signal to begin with you are only amplifying the noise.
He is correct. The MOST IMPORTANT factor is that your antenna can "see" the transmitting antenna. This means you want you antenna to be as high as practical (and that might not be high enough to do the job).

There was a recent discussion here in another thread on this issue, and most of us agree that how far you can receive is really a factor of mostly the height above average terrain of each the transmitting and receiving antennas. If you're using a directional antenna (which the discone is NOT), then you can get some "free" signal gain with the antenna. The next questions that come to my mind are; how strong is the desired signal at the antenna, and how much coax (loss) do you have to get that signal to the receiver?

Especially at 800MHz, the signal loss through coax can add up to quite a bit. This is where a GOOD QUALITY low noise amplifier can help. The boost it gives you is enough to overcome the loss it will have going down the coax, couplers, any splitters, etc. And you might have a little net gain from it.

If your antenna can not 'see' the transmitting antenna, you will be at the mercy of atmospheric conditions as to whether or not you will be able to receive what you want. Your uncle can educate you on that. Or read this. Good luck.
 

zz0468

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First off, you're going to have to have realistic expectations. I live in the LA area, and am VERY familiar with propagation over the mountains. Depending on what you're trying to listen to, chances are, you're not going to be able to hear it no matter what antenna or preamp you use. Most of the 800 systems in the area are specifically designed NOT to cover outside their service areas because of the high level of frequency reuse. Part of what you'll run into is, just as an example, if you're trying to listen to an LA City system that's co-channel with, say, a San Bernardino County system. From the desert, you're more likely to hear San Bernardino county, so keep that in mind. EVERY frequency is used by more than one agency.

You stand a chance of hearing some low band and VHF signals, if the geometry is right. It's pretty much going to be hit and miss, but by all means, TRY. Where in the desert are you, and what specifically are you trying to hear?
 

tomasG

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I want to listen to Highway Patrol, county fire, and the county 800 system that is used out here at the county hospital and the lakes. L.A. City Fire can be heard but not very well, which is why I asked about the performance of the ST-2 on 800. I can also hear some LAPD. I was mainly suspicious of someone trying to sell me an expensive preamplifier after talking to my uncle.
 

zz0468

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I want to listen to Highway Patrol, county fire, and the county 800 system that is used out here at the county hospital and the lakes. L.A. City Fire can be heard but not very well, which is why I asked about the performance of the ST-2 on 800. I can also hear some LAPD. I was mainly suspicious of someone trying to sell me an expensive preamplifier after talking to my uncle.
You have some pretty stiff requirements, trying to listen to lowband, T-band AND 800. Separate yagis feeding separate receivers is the right way to do it.

As to preamps, Angle Linear makes some EXCELLENT single band preamps that are probably the best available at any price. Advanced Receiver Research also makes some decent ones, and they have a wideband unit suitable for scanners. It's worth the money they're asking for it. That, and a log-periodic beam antenna is probably as close to what you're looking for as you'll get.
 

tomasG

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I honestly don't think that my requirements are stiff and see them as no different than anyone anywhere. Public safety agencies use different bands. I am in Lancaster, CA. I can hear much of county sheriff and fire already. I can hear Kern county sheriff and fire, but my discone doesn't do well on low band or 800, which leads me back to the original question about the ST-2 and how well it does on 800. I talked again with my uncle today and he said the same thing again, that adding an amplifier won't help you hear something that you cannot already hear. I don't know how to use two different antennas at the same time, like one that works great down below and another that does great on 800.

Is there something like a combiner like I've seen on satellite TV web pages? The split UHF from VHF or something like that. And what about the Wingard wide band amplifiers I see there that seem to cover 40-2000mhz? Reading the reviews the Wingards are pretty good on not overloading (they have different models.) So maybe a ST-2 and a Wingard? I don't see myself spedning a lot of money on professional amplifiers that may not even work.
 

zz0468

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I honestly don't think that my requirements are stiff and see them as no different than anyone anywhere.
They are in terms of your original post where you stated you live in the desert and want to receive more LA stations. If you're content to listen to what's being transmitted on your side of the hill, your requirements suddenly become much more realistic. You have to remember, engineering types who design systems use that terrain for isolation and co-channel purposes because signals frequently WON'T go over them.

To those outside the LA area and unfamiliar with the terrain, said "hill" can be anywhere from about 3500 to 10,000 feet, depending on where the OP is,and what he wants to listen to.
 

tomasG

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At this point I'd really just like to know how the performance of the ST-2 is on 800mhz. I need to order an antenna.
 

trooperdude

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Is there something like a combiner like I've seen on satellite TV web pages? The split UHF from VHF or something like that.
Search the archives here for the custom "diplexer" thread. A combiner will only serve to null out what you want to listen to and make the situation worse.

Optimum reception is band-specific antennas fed into a quality diplexer, then use a LOW NOISE amplifier into a distribution circuit (like minicircuits), and feed multiple receivers from there.

IF you only have one receiver, then just go band specific antennas fed with good quality coax, into the diplexer, then straight from the diplexer (or triplexer if you run 3 different band specific antennas) into your receiver.

Stay away from multiple yagis, combiners, etc. unless you know exactly what you are doing with regard to phasing properly, etc. Your results will be worse.

My setup is:

42mhz coaxial sleeve half wave
150/460 commercial dual band antenna
800mhz 6db gain omni

3 separate coax feeds into a custom triplexer

From the triiplexer, a single feed into an 18db gain Watkins-Johnson very low noise amplifier

Fed into an 8 port Minicircuits distribution bus w/ high isolation

Everything except the triplexer was purchased surplus for pennies on the
original dollar.

Quality doesn't have to be expensive.
 

tomasG

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I've been reading about preamplifiers and see that all of them recommended for scanners say that they shouldn't be used in metropolitan areas. But then I've read about HDTV amplifiers that say just the opposite, have good amplification, and good rejection of overload. The Wingard in particular seem to be very popular on the HDTV forums and the users claim that they don't overload easily. The off-the-air models cover channels 2-69 and some go to channel 82 right where public safety is at.They are designed not to overload with 50Kw TV transmitters and directional antennas.

Has anyone tried these amps?
 

arvellabill

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antennas and preamps

There are a few items that no one advised you on, first your line of sight is 50 % of the answer the repeater repeater location is just as important for instance you could be 100 miles away from the dispatch center but only a few miles from a repeator or control station. For years I have used a customized uhf antenna and a omnidirectional antenna, I ran my two feeds into my house and used a TV vhf/uhf splitter hooked up backwards so I was getting both signals seperately I ran the uhf antenna through a Grove preamp which I have used for at least 30 years and it still works great.The omni directional feed ran through a radio shack preamp, I have been able to pick these signals out of nothing but noise, these preamps work great and with the advent of digital systems where there is no carrier noise they work twice as good. I customized my uhf antenna from an old tv antenna. We here in the washington DC area had before cable a company called Super Tv which was a signal station movie channel I believe the freq was somewhere in the 750 800 meg's I added an inch to each of the 14 elements top and bottom. This worked perfect and i know I still see some of these antennas on rooftops as the company did not bother to pick up their equiptment when they went bottom up. With a set up like this you have to change the antenna from a horizontal to a vertical which is very easy If you can't find an old Super TV any TV antenna will do after you change the lay out "hori. to vert." it is tuned to scanner vhf HI/ Lo uhf and 800 without any changes. arvellabill {Bill}
 

zz0468

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I've been reading about preamplifiers and see that all of them recommended for scanners say that they shouldn't be used in metropolitan areas. But then I've read about HDTV amplifiers that say just the opposite, have good amplification, and good rejection of overload. The Wingard in particular seem to be very popular on the HDTV forums and the users claim that they don't overload easily. The off-the-air models cover channels 2-69 and some go to channel 82 right where public safety is at.They are designed not to overload with 50Kw TV transmitters and directional antennas.

Has anyone tried these amps?
People are trying them, and results are going to be hit and miss. The needs of a broadcast tv receiver (digital or analog) are quite different than the needs of a scanner. In a preamp, the one parameter that outweighs everything else is called "noise figure" (or NF). The typical scanner is going to have a noise figure in the 4-6 db range. The typical television receiver is going to have a noise figure higher than that. If the NF of the preamp is higher than that of the receiver, it will harm, not help, weak signal reception. A 7db NF TV preamp will help a TV receiver. That same preamp would deafen a scanner to weak signals, even as it made strong signals stronger.

You may see a low quality (i.e. high NF) preamp make "more bars" on the scanner, but the real measure is how it behaves with weak signals. Generally speaking, TV preamps are a bad bet, but some people report good results.

As for overloading with 50 kw tv transmitters, that's not really a consideration with these things.

What you want is a preamp with NF as low as you can get. If it's not in the specs, than don't bother with it. Preamps are readily available with NF as low as .5 DB for single bands, and around 2-3 dB that are wideband enough for general scanner use.

BTW, Winegard is held in particularly low esteem among people in the broadcast industry. A lot of their products have been known to oscillate and actually create out-of-band interference.
 

tomasG

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Thank you for your reply.

The Wingard is held in high esteem amongst HDTV users and they reference oscillations as well. Some of them are engineers. But as with nearly anything in life I accept that ones mileage may vary. The Wingard AP8700 or similar have a noise figure of 2.8. I am studying electronics in college and understand decibels.

I've looked at the Dressler, the Angle Linear and the Advanced Receiver and all require external power, whereas the Wingard and similar have a bias T already. Since I want to tower mount it I need some sort of power. Even the LNA's at Scannermaster need power. I thought of putting a small weatherproof box on the small mast that I have with a gel cell and a small solar panel like freeway call boxes do, but I don't know that the return on the investment would be worth it. I keep coming back to what my uncle has said several times: you cannot amplify a signal that isn't already there. I can hear Castaic and Piru on 800 already, so an amp would likely help.

My uncle also mentioned another approach of using something called a duplexer and reversing it where I could use a 800mhz antenna and then another antenna for everything else. On Solid Signals they have something similar called a combiner but the frequency cutoffs aren't where I need them.
 

gmclam

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Amplifiers

I've been reading about preamplifiers and see that all of them recommended for scanners say that they shouldn't be used in metropolitan areas. But then I've read about HDTV amplifiers that say just the opposite, have good amplification, and good rejection of overload.
One more thing to consider. Every metropolitan or geographic area is different, so it is probably not a good idea to make such a broad statement.

Where I live, near Sacramento California, I would consider this one large metropolitan area with nearly 2 million people. But the TV transmitters are about 35 miles direct distance from me. So when looking at only the overload aspect of "HDTV amplifiers", it is not going to happen here from broadcast TV signals.

However, there are lots of locations where the signals come from I monitor on my scanners, and that does not even include mobiles. Then there are paging systems, cell towers and other signals that use the same spectrum as I want to monitor. All of these signals are likely to overload an amplifier designed to pick up TV dozens of miles away.

They are designed not to overload with 50Kw TV transmitters and directional antennas.
When you are 2 miles (or so) from such a transmitter? I'd suspect not.
 

tomasG

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The statement that amplifiers should not be used in metropolitan areas was made by a notable scanner reseller on their web site. It isn't my broad statement, just as the comments of the HDTV enthusiasts are not mine.

With respect to OTA amplifiers for TV and HDTV that claim not to overload, wouldn't it make sense that since TV transmitters use kilowatts the amplifier is probably very well suited for scanning as far as overload. The HDTV amplifiers are recommended based on distance from the transmitter and the shorter distance models have 11db gain up th the longer distance models that have like 28dB gain. I located the LNA amplifiers sold by a notable scanner reseller on a HDTV web site, so I can assume that its the same amplifier :)

But I've also read that just putting an outside antenna on a scanner can cause overload and pager noise. Others have suggested that if running any kind of amplifier one should add a PAR intermod filter. I am learning as I go and I can tell that there are differing opinions on this topic and feel like I am caught int he middle. I don't have a lot of money and just want to make a good decision. My uncle stresses using a better antenna before adding a preamplifier, but it doesn't seem like there is a one-size-fits-all solution.
 

zz0468

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The statement that amplifiers should not be used in metropolitan areas was made by a notable scanner reseller on their web site. It isn't my broad statement, just as the comments of the HDTV enthusiasts are not mine.
take what you read on websites directed toward consumers with a grain of salt. That means HDTV dealers, that means scanner and accessory dealers. They're not immune to propagating myths and misinformation.

With respect to OTA amplifiers for TV and HDTV that claim not to overload, wouldn't it make sense that since TV transmitters use kilowatts the amplifier is probably very well suited for scanning as far as overload.
On the surface, yes, that would appear to make sense. In actuality, you can't make any such assumptions unless you read the device's specifications, and understand them. The fact is, however, that like I said before, there is NO consideration given to the fact that a TV preamp is listening to (watching?) a 50kw transmitter. And of all the specifications given to preamps directed to a consumer, the gain is one of the least important ones to look at.

The HDTV amplifiers are recommended based on distance from the transmitter and the shorter distance models have 11db gain up th the longer distance models that have like 28dB gain. I located the LNA amplifiers sold by a notable scanner reseller on a HDTV web site, so I can assume that its the same amplifier :)
It probably IS the same amplifier. All the more reason to beware.

But I've also read that just putting an outside antenna on a scanner can cause overload and pager noise.
This is very true. An amplifier will amplify signals, noise, and it will add it's own noise to the mix. It will amplify signals that you don't want to listen to. It will turn signals you don't want into noise that degrades signals that you DO want. It can be a bit tricky using an amp and actually getting a real improvement.

Others have suggested that if running any kind of amplifier one should add a PAR intermod filter.
be careful of blanket statements like that. WHAT filter do you need? It's going to be very dependent on what specific signals you need to filter out (or in). If an FM broadcaster is swamping your preamp, a 152 MHz paging filter isn't going to help. In the real world, it can take things like spectrum analyzers to see what's actually going on, and then determine what needs to be done to fix it.

I am learning as I go and I can tell that there are differing opinions on this topic and feel like I am caught in the middle.
Yep. You are. And many of the opinions that get expressed are not worth the paper they're printed on. Verify from several independant sources before you plunk down cash.

I don't have a lot of money and just want to make a good decision. My uncle stresses using a better antenna before adding a preamplifier, but it doesn't seem like there is a one-size-fits-all solution.
There IS no one size fits all solution. that's just the way it is. You'll even find that the solution for one particular reception problem is exactly what you DON'T want for another. Now you're beginning to see why lots of guys here have multiple scanners and multiple antennas.

Sounds like your uncle knows what he's talking about. I'd pay attention. Good luck!
 
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