Using Amplifer to boost signals

[Flatshovel]

Hello all,
I have a rather crazy question. If you hookup a VHF/UHF amplifier that you use for a regular television set that uses a tv antenna, will it hurt a scanner if you hookup up to it? I do realize that it may pick up more noise but it may help increase very weak signals. It won't burn out the receiver in the radio will it? The amplifier I have says 20db gain. Just curious if It will work, I know there are other amplifiers on the market. Has anyone tried this, if so what were the results?
Thanks,
Joey

 

[SouthSoundScanner]

I have done that, it won't hurt the scanner. In my case it didn't improve reception. But your results could be different, so go ahead and give it a try.

 

[n2mdk]

It won't hurt anything, if you see this thread you will see lots of people use them in multiple scanner hookups to a single antenna. http://www.radioreference.com/forums/showthread.php?t=84295

 

[gmclam]

If you want effective results, connect your outdoor scanner antenna to the TV amplifier and the amplifier output to your scanner. TV antennas are usually lousy for scanner signals. But there is nothing special about TV amplifiers - as long as they handle the band/freqs you want to hear.

 

[Don_Burke]

A scanner antenna feeding a TV amp is a common setup.

The amplifier will also amplify TV and FM signals and may desense your scanner, so if does not seem to be working well, that is something to check on.

If you already have all of the parts, it hurts nothing to try it.

 

[mciupa]

Hello all,
I have a rather crazy question. If you hookup a VHF/UHF amplifier that you use for a regular television set that uses a tv antenna, will it hurt a scanner if you hookup up to it? I do realize that it may pick up more noise but it may help increase very weak signals. It won't burn out the receiver in the radio will it? The amplifier I have says 20db gain. Just curious if It will work, I know there are other amplifiers on the market. Has anyone tried this, if so what were the results?
Thanks,
Joey

In my case it amplified paging tones and other unwanted signals.
If you live in a relatively "clean" RF zone (away from an urban setting) you may be pleased.

 

[n1das]

In my case it amplified paging tones and other unwanted signals.
If you live in a relatively "clean" RF zone (away from an urban setting) you may be pleased.

Some amps have an on/off switch labeled "FM Trap" to switch in a notch filter for the FM broadcast band (88-108MHz). I've found with these amps it's worthwhile to have the FM Trap set to ON. Strong local FM broadcasters can also overload and de-sense a TV amp.

As usual YMMV. Good luck.

 

[n1das]

ARRGGHH!! Website problems resulted in duplicate post!

In my case it amplified paging tones and other unwanted signals.
If you live in a relatively "clean" RF zone (away from an urban setting) you may be pleased.

Some amps have an on/off switch labeled "FM Trap" to switch in a notch filter for the FM broadcast band (88-108MHz). I've found with these amps it's worthwhile to have the FM Trap set to ON. Strong local FM broadcasters can also overload and de-sense a TV amp.

As usual YMMV. Good luck.

 

[n1das]

Website problems - duplicate post - I can't delete!

In my case it amplified paging tones and other unwanted signals.
If you live in a relatively "clean" RF zone (away from an urban setting) you may be pleased.

Some amps have an on/off switch labeled "FM Trap" to switch in a notch filter for the FM broadcast band (88-108MHz). I've found with these amps it's worthwhile to have the FM Trap set to ON. Strong local FM broadcasters can also overload and de-sense a TV amp.

As usual YMMV. Good luck.

 

[kb2vxa]

"In my case it amplified paging tones and other unwanted signals."

You're not alone, that's a common problem with ALL "DC to light" preamplifiers including those intended for scanners. In an RF rich environment they overload the receiver causing intermod and in some cases the intermod can occur in the amp itself. That's why most frown upon such devices and go with the tried and true philosophy of "90% of the station is on the roof". In other words nothing beats a proper antenna and coax.

David, I think we all got the point the first time. (;->) Actually the FM trap's purpose is to eliminate herringbone interference on channel 6 when a strong FM signal is present. FYI most VHF TV antennas have breakaway elements for FM reception, if channel 6 is a problem you break them off.

 

[k9rzz]

Sometimes they help. Sometimes they don't. It doesn't hurt to have one around.

Ebay. $20. Works to about 1 Ghz. FM trap works well. Worth every penny. (NOTE: F connectors)

 

[gmclam]

I am using the TA-36 for my TV system. UHF & VHF are separately adjustable, there is a switchable FM trap and it is a sloped amplifier.

 

[N_Jay]

I am using the TA-36 for my TV system. UHF & VHF are separately adjustable, there is a switchable FM trap and it is a sloped amplifier.

5 to 7 dB noise figure sucks for a front end amp.

 

[gmclam]

ATSC only

5 to 7 dB noise figure sucks for a front end amp.

It's a lot more gain than I need too. But with ATSC, I don't see the noise. As long as the receivers lock onto the signals (which they do for signals from about 100 miles away), it's all good.

As I've written before, I'm not using any amplifier for scanner reception.

 

[N_Jay]

It's a lot more gain than I need too. But with ATSC, I don't see the noise. As long as the receivers lock onto the signals (which they do for signals from about 100 miles away), it's all good.

As I've written before, I'm not using any amplifier for scanner reception.

The noise figure for a receiver system, and therefor the overall sensitivity of the entire receiver system is set prodominently by the noise figure of the first active stage.

 

[kb2vxa]

Hi again,

For once N_Jay is right (;->) the front end S/N ratio is all important especially in TV work where the video is AM. Noise = snow so he's right, that amp sucks. BTW, as far as I'm concerned cable is horrible for snow because of all the active components along the signal path each adding noise to the signal. Take a closer look at the screen and you'll see a ton of noise in the video, that really fine grain snow is snow just the same. I used to work for a manufacturer of TV broadcast equipment where the noise specs are unbelievably low and in test most of the time unmeasurable. That's because in the chain it all adds up and with cable it's length makes broadcast look like a jumper cable. Now with digital it really doesn't matter quite as much as analog but that's a recent and rather expensive development.

Back to the original subject, about the last thing you want when you use that kind of amp for anything but a cable DA is tilt. The manufacturer calls it "slant", same thing. The only thing that's good for is compensating for coax loss vs. frequency and then you have adjustable gain for each band. Without a wave meter on the far end of the coax there's no way in hell you'll get the frequency response balanced out and that's a very expensive bit of equipment even the average cable guy doesn't have. Oh I've seen it done but only when they're wiring up a building.

That's probably why Larry is now a comedian, he just didn't know how to git er done with a wave meter. He thinks it's some new fangled fishing toy and no self respecting redneck brings one of those things aboard a bass boat.

Hmmm, all the more reason (going back to my original post) why 90% of the station is on the roof and not in the shack.

 

[N_Jay]

For once N_Jay is right (;->)

Well aren't you the generous one.

I am so happy, I have been blessed by the great and powerful Warren; he whose does not need to properly use the quote feature!

 

[gmclam]

digital TV vs scanners

...the front end S/N ratio is all important especially in TV work where the video is AM. Noise = snow so he's right, that amp sucks.

video may be AM in your world but not mine. As I wrote before, I am only interested in receiving ATSC. And the reason I selected this amp was because of the amount of gain, as my focus was to receive distant TV signals. Something now outlawed by cable & satellite (if protected).

BTW, as far as I'm concerned cable is horrible for snow because of all the active components along the signal path each adding noise to the signal. Take a closer look at the screen and you'll see a ton of noise in the video, that really fine grain snow is snow just the same.

YUP and you guys all PAY for that stuff!

...about the last thing you want when you use that kind of amp for anything but a cable DA is tilt. The manufacturer calls it "slant", same thing. The only thing that's good for is compensating for coax loss vs. frequency and then you have adjustable gain for each band. Without a wave meter on the far end of the coax there's no way in hell you'll get the frequency response balanced out and that's a very expensive bit of equipment even the average cable guy doesn't have.

I disagree. Everyone has some length of cable from their antenna to their scanner(s). And since we now scan from low band to 900 MHz and above, cable loss is much more significant of a factor than ever. I think everyone knows that higher frequencies lose more than lower.

Regarding the adjustments; my bad. I figured that people here who were installing amps would have an idea of the gain/etc they need. I do have the equipment, and would rather have the adjustments to balance things out. The alternative is to put in a fixed gain amp and expect it is going to do what you want.

My post has gotten this off track a bit. Certainly the amp someone would pick for digital TV is not the same as the amp best for (analog) scanning. And it's been said here many times; often putting in any amp makes a bad situation worse. So from a scanning point of view, perhaps this is a good example of what not to do.

Hmmm, all the more reason (going back to my original post) why 90% of the station is on the roof and not in the shack.

SO perhaps you should move your receivers to the roof! Otherwise downlead is needed. And NO downlead is perfect. Some people add amps to mitigate the imperfection. I think this discussion has shown it is not that simple.

 

[N_Jay]

video may be AM in your world but not mine. As I wrote before, I am only interested in receiving ATSC.

OK, but isn't 8VSB an AM modulation?

And the reason I selected this amp was because of the amount of gain, as my focus was to receive distant TV signals.

Well, if you understood the issues involved you would understand why noise figure is as, if not more important than gain.
(Seems like another case of someone not "understanding" everything they "know"!)

I disagree. Everyone has some length of cable from their antenna to their scanner(s). And since we now scan from low band to 900 MHz and above, cable loss is much more significant of a factor than ever. I think everyone knows that higher frequencies lose more than lower.

Here I will partially agree with you.
If your line loss is "excessive", then some slant is ok, but in general I doubt it will ever make a noticeable difference in any system where you are working at the threshold.

Certainly the amp someone would pick for digital TV is not the same as the amp best for (analog) scanning.

Why not?

 

[kb2vxa]

Hi again,

Still I can't resist nerdy Tech Wars just to confuse and/or bore the heck out of the jocks.

N-Jay, I don't need to properly use the quote feature, I don't use it at all and I won't, I won't, I WON'T! Such is the privelidge of the Grand Exalted Poobah of Radio (Reference) and if you try to make me I'll hold my breath until I turn blue.

Hmmm, eight layer vestigial sideband... so is it AM? No, it's USB with full carrier. Oh I'm sure you know the emission designator, you know everything. Since you do you recognize the similarity to analog NTSC VSB I'm sure inasmuch as only the type of modulation has changed. Well, if nothing else they no longer use two transmitters and a combiner.

Clam, now that I've thrown rocks at N_Jay I'll let you argue with him, it should be fun reading.

I can see the point in using tilt, slant, slope or whatever even with a scanner but still it only makes a difference in long cable runs. I saw a real problem when I moved into this building, the landlord had a Frankenstein cable setup with a plethora of splitters here and there and long runs, quite a mess. The VHF Lo Band signals were bad enough but when it got into Hyper Band it was like watching a white goose in a blizzard. Recently he installed a proper DA with individual cable runs, what a difference!

"Well, if you understood the issues involved you would understand why noise figure is as, if not more important than gain.
(Seems like another case of someone not "understanding" everything they "know"!)"

Once again N_Jay is right, regardless of the application noise is noise. I went off on the TV tangent just to make that point, a strong signal is still crap if it's full of noise. Anyone with an on line computer should know that, line noise causes a high BER resulting in excessive resends and slows down the internet connection. Then there's BPL and what radio signals do to it, interference works both ways. (evil grin with horns) Before I go off again let me remind you the same thing happens to DTV, there's lots of things that all come down to noise interrupting the data stream that causes pixelization, halting, and in a worst case scenario the dreaded blue screen when the buffer empties.

"Certainly the amp someone would pick for digital TV is not the same as the amp best for (analog) scanning."

N-Jay is being uncharacteristically kind. I being reminded of the snake oil "HDTV antennas" would rake you over the coals for being patently ridiculous, an amp is an amp is an amp. Well, maybe I just did so I'm sorry but please stop and think a minute. What's the difference between digital TV and analog scanning? Oh don't say video or I'll shoot you where it hurts! (;->)

OK, enough of that, this is SUPPOSED to be a scanner forum but I'll leave you with the thought for today. N_Jay is like a juice commercial on TV with that slap upside the head bit, "Gee, I could have had a V-8!"

INCOMING!!!