Gre Super Amplifier Problem

[hfgentry]

I added one to my system tonight ... It helps rcv conv channels, but loses all 800 truncked, APCO 25, a type IIi, and a type II. I take it out of line and get the signals back?? Whats up with it??

Using BC796D and Discone ant.

The Amp is brand new from GRE.

 

[N_Jay]

I added one to my system tonight ... It helps rcv conv channels, but loses all 800 truncked, APCO 25, a type IIi, and a type II. I take it out of line and get the signals back?? Whats up with it??

Using BC796D and Discone ant.

The Amp is brand new from GRE.

Where in line are you installing it?

What type and how much line before it?

What type and how much line after it?

What type of antenna?

Where are you? How close to ANY readio sites?

As I have have mentioned before, it is not the type of signal that matters.

What does matter is the frequency, the strength, and the RF noise in the area.

 

[hfgentry]

Putting it in line just before the scanner. I am not trying to be smart or hateful but I understand the need for a good antenna and coax. The problem is:

Without the amp I hear Fulton County (type IIi) with static
Without the amp I hear Forsyth County (APCO25) Clear

With the preamp in line I do not hear either.

any idea why??

 

[click23]

The preamp needs to go right after the antenna. Putting it that close to the scanner only aplifies the noise from the coax. Does this amp have an adjustable gain? I would move it right after the antenna, or as close as you can get it. If you are still having problems I would try to adjust the gain if possible. You might also want to check out this link about preamps.

Robert

 

[loumaag]

Whereas the ideal place for a preamp is at the antenna, the GRE SuperAmp is not designed to be used outdoors, so that is pretty silly advice.

The answer is, as so many people have pointed out over the months in the fourms here, a pre-amplifer amplifes everything, noise, signals, everything. Using a pre-amp on a scanner invariably does two things:

1. On marginal signals, it increases the signal & noise at the antenna input to the scanner, with luck this will help you understand those signals better.

2. On clear signals, it increases the signal to the point that the front end of the scanner is overloaded and can no longer differentiate the signal from the total amout of RF being fed it.

Those two reasons are why the pre-amp has an adjustment on it. But in general, a pre-amp for a scanner is a bad idea. Most scanners are already peaked so much that putting an outside antenna on them overloads the front end, imagine what an amplifed signal does to them.

 

[N_Jay]

1) the cable does not make noise, it just attenuates all the signals.
They attenuate higher frequencies most.

2) Pre-Amps amplify everything, but also tend to reduced the difference between strong and weak signals.

3) Pre-Amps also add noise.

4) Any signal applied to the front end of a radio reduces its sensitivity to other signals.

So you want oi give a pre-amp the best signal posible to start with (at the antenna end of the cable).

You don't want to use a pre-amp in areas where there are other strong signals.

You can not expect a preamp to help signals below the noise floor.

You can only expect worse reception from signals that are good without a pre-amp.

The modulation, (Digital vs. Analog) does not matter.

The format (Trunked vs. Conventional) does not matter.

This is science, not superstition. You will save many times the cost of a good book and antenna system design!!!!!

Oh, and one more thing:

WHen you ask a question and some one asks some clarifying questions, if REALY pisses them off when you continue the thread without taking the time to answer the questions asked! :evil: :evil: :evil:

For Example;

Where in line are you installing it?

What type and how much line before it?

What type and how much line after it?

What type of antenna?

Where are you? How close to ANY readio sites?

 

[LarrySC]

Short answer. A BC-796 does not need an amp. That amp has too high a gain factor. The best amp is an antenna cut for VHF/UHF/800. If you did need an amp it should not be over 1db gain. I installed a 3001 for a local media traffic office. The gain was set LOW. The scanner was 800 only. The station was 30 miles away. The antenna was a yagi. The coax run was over 100'. Now this installation does work exactly like you would expect it to. Loud and clear w/ no intermod. Your problem is simply too much antenna for too much amp. Good Luck on all your projects. Larry

 

[Tweekerbob]

You can only expect worse reception from signals that are good without a pre-amp.

That was his probelm, no?

N-Jay, why didn't you just say that in the first place instead of asking a bunch of silly questions, silly meaning, the answers wouldn't have changed your opinion in the above referenced quote?

Then to get PISSED OFF because people don't answer your inmaterial questions. Wow.

p.s. He answered your question of what antenna he is using before you even asked it. Please REread the initial post, especially before formulating any more silly questions.

 

[N_Jay]

You can only expect worse reception from signals that are good without a pre-amp.

That was his probelm, no?

N-Jay, why didn't you just say that in the first place instead of asking a bunch of silly questions, silly meaning, the answers wouldn't have changed your opinion in the above referenced quote?

Then to get PISSED OFF because people don't answer your inmaterial questions. Wow.

p.s. He answered your question of what antenna he is using before you even asked it. Please REread the initial post, especially before formulating any more silly questions.

Well that was the simple answer, but like most simple answers is Over-simplified!

Sorry for missing the point about the antenna.

Notice he did not say the signals were good before adding the pre-amp, so providing the oversimplified answer at that point would have required a bunch of ASSUMPTIONS, and could have just as well been a WRONG answer.

The questions asked were to lead to discussion of how to use a pre-amp and when to expect decent results.

We never got there.