GRE Super Amplifier

[Universaldecoder]

The right receipe?

Is the GRE super amp worth the money? Does it improve the range?

Just using my imagination here. I haven't tried it, but I'm thinking it should work....

1. Use a tuned antenna with a narrow bandwidth (for example 150-162 mhz)

2. Attach the antenna to a bandpass filter along the same narrow bandwidth (150-162 mhz)

3. Attach the other end of the bandpass filter to the GRE amplifier

4. Finally attach the other end of the GRE to your scanner and scan any frequency that falls in the 150-162 mhz range.

With just the GRE, I would think that all you are doing is amplifying pretty much every thing, and that's why scanners get overloaded. With the above setup, you attenuate noise, and amplify the signal in interest.

 

[mancow]

Provided you don't have any very strong transmitters in that passband it should work great.

 

[Universaldecoder]

Ooooppps...

Provided you don't have any very strong transmitters in that passband it should work great.

Hmmmm....the range I used as an example contains pager freqs....DOH!

 

[proquist96]

gre

I want to receive signals from 100+ miles away if its possible. Maybe a nice antenna on my roof with an amp.

 

[Universaldecoder]

Impossible?

I want to receive signals from 100+ miles away if its possible. Maybe a nice antenna on my roof with an amp.

"Not" - impossible, but it's gonna cost you. I've communicated via satellite with a handheld putting out 5 watts using a Yagi antenna (Arrow Antenna). I've also received and transmitted to a NASA space shuttle and the IS. So yes, I would think it is possible to receive a land base system 100 mi away.

But the two major difference are.....

1. Objects in your way. There are not many physical objects between a spacecraft and a
land based rf system. Weather and the atmosphere are probably the only hurdles to
overcome as well as an occasional Sun Spot when land based system is contacting a Spacecraft.

2. Competing signals (aka RF noise). You and I live in an ocean of noise. Gotta consider
how many other systems transmit on the same or close to the same freqs between you and that system your
trying to receive 100 mi away. Obviously, these competing signals will be stronger. How do you overcome
them?

I can only deduce from what I know that........the signals your trying to receive are already around you, but they are faint (transmitter is 100 mi away), and like I said there are other signals that are stronger that will drown out the ones you want all around you. An amplifier like the GRE isn't going to sort out these signals. It will amplify all, and then it'll be up to your receiver to pickout the one your interested in. We know how selective our wideband scanners are....right.

I see this question about the GRE Super Amplifier resurface at least once every year. The major misconception, I think, is that most people perceive an amplifier will allow their scanner to REACH OUT to a distant transmitter. That's wrong.


This makes me think of SETI and SETI at Home. So, below is a setup worth considering, but probably in a smaller version for your application - it's used to receive very faint signals....I'll see if I can come upon the electronics used for this antenna - electronics that sort and filter out the noise. I bring this up because it just dawned upon me that we can probably apply what the engineers developed for this radio telescope to our situation also...but in a smaller and hopefully more economical way!

 

[Universaldecoder]

By the way.....

www.scannermaster.com has a slew of bandpass filters, and "Pre-Amplifiers" - these are amplifiers with built in band pass filters! Check em out.

 

[trooperdude]

Hmmmm....the range I used as an example contains pager freqs....DOH!

Don't forget National Weather Service transmitters will also kill ya on overload.

 

[trooperdude]

I want to receive signals from 100+ miles away if its possible. Maybe a nice antenna on my roof with an amp.

A physics primer on Radio Horizon and what is possible to receive:

Here is an online VHF/UHF calculator if you don't want to do the math:
http://www.qsl.net/w4sat/horizon.htm


radio horizon range (RHR): The distance at which a direct radio wave can reach a receiving antenna of given height from a transmitting antenna of given height.

The radio horizon range in nautical miles, R, is given by the relation R = 1.23(h t 1/2+ h r 1/2), where h t and h r are the heights of the transmitting and receiving antennas in feet.

The radio horizon range, R, in nautical miles is also given by the relation R = 2.23(h t 1/2+h r 1/2), where h t and h r are the heights of the transmitting and receiving antennas in meters.

The effective Earth radius, 4/3 times the actual Earth radius, is used in deriving the formula. Second-order differentials are neglected. They are of the order of 0.1%.

 

[Universaldecoder]

A physics primer on Radio Horizon and what is possible to receive:

Here is an online VHF/UHF calculator if you don't want to do the math:
http://www.qsl.net/w4sat/horizon.htm


radio horizon range (RHR): The distance at which a direct radio wave can reach a receiving antenna of given height from a transmitting antenna of given height.

The radio horizon range in nautical miles, R, is given by the relation R = 1.23(h t 1/2+ h r 1/2), where h t and h r are the heights of the transmitting and receiving antennas in feet.

The radio horizon range, R, in nautical miles is also given by the relation R = 2.23(h t 1/2+h r 1/2), where h t and h r are the heights of the transmitting and receiving antennas in meters.

The effective Earth radius, 4/3 times the actual Earth radius, is used in deriving the formula. Second-order differentials are neglected. They are of the order of 0.1%.

Neato, thanks Trooperdude.

 

[Universaldecoder]

I want to receive signals from 100+ miles away if its possible. Maybe a nice antenna on my roof with an amp.

By the way, what range of frequencies are we talking about?

 

[Universaldecoder]

Here's some more....

www.hamtronics.com

Checkout their Pre-amplifiers! I'm planning on investing in the 800-960 mhz unit. ALSO, open up one of the PDF manuals about their pre-amps to get an idea on what these things are really are, and what they can do. Good stuff.

 

[Universaldecoder]

www.hamtronics.com

Checkout their Pre-amplifiers! I'm planning on investing in the 800-960 mhz unit. ALSO, open up one of the PDF manuals about their pre-amps to get an idea on what these things are really are, and what they can do. Good stuff.

I've been corresponding with Hamtronics in regards on how I can tune their 800 mhz pre-amp. Interesting to note that two rounds of emails have occurred and I still have not gotten the instructions on how to. However, the company does offer the service for an additional $10. Do you think this is why?

 

[proquist96]

gre super amp

Yes, i think the problem is the amp will amplify everything from 100mhz-1ghz maybe they need to design a narrow band amp or have a selector switch to only amplify 854-860mhz only, that is my local mountains about 100 miles away and i have a straight shot to point a dish? type or l-l-l-i-i-?

 

[Allan_Love_Jr]

Just using my imagination here. I haven't tried it, but I'm thinking it should work....

1. Use a tuned antenna with a narrow bandwidth (for example 150-162 mhz)

2. Attach the antenna to a bandpass filter along the same narrow bandwidth (150-162 mhz)

3. Attach the other end of the bandpass filter to the GRE amplifier

4. Finally attach the other end of the GRE to your scanner and scan any frequency that falls in the 150-162 mhz range.

With just the GRE, I would think that all you are doing is amplifying pretty much every thing, and that's why scanners get overloaded. With the above setup, you attenuate noise, and amplify the signal in interest.

That's the way mine is set up. And it works great.

 

[proquist96]

i will look into the filters i remember cable tv used filters to filter out HBO. I need a filter to make the amp work effective in my certain range.

 

[blueangel-eric]

My GRE preamp is either defective or they are not good. Using my 2 meter radio i tested it on receive and with the gain turned all the way down the signal is worse than when it is off. When the gain is all the way up the signal is not much better than the amp being off, for being 20db gain. I remember years ago it worked great but i think it went bad. I never used it that much though because of the overload my scanners got.

Eric Burris
KC0LDT

 

[oldtimeradio]

My 2 cents... an additional source of commercial grade preamps.

I have 2 of ARR's 30mhz to 1Gig Model P30-1000/11VD.
Work good for me, the price was right for me...free. Don't Ask...
Also have a package of replacment GaAsFET's for those lightining storms.
Even mounted indoors GaAsFET preamps don't like lightining.
On base scanner (780XLT) I have 2 notch filters to suck out the 2 strongest VHF paging channels. Using Austin "Ferret" base antenna.
Also have a bunch of their 800mhz preamps from the cellular days, retuned and using on several scanners for trunking.

http://www.advancedreceiver.com/

 

[jmp883]

I love how this thread keeps popping up periodically...I also love the responses.

Ignore those posters who say it's a waste or that you have to have one in order to hear anything.

The answer lies in the middle. I live in northern NJ, about 30 or so miles northwest of NYC. I should be in the middle of a monitoring heaven but because of living in a valley my scanners are severely limited in what they can hear. For me my GRE amp has been the best piece of equipment I've put in my listening post. Before I had the amp I could only hear my town and the one or two towns around me. That was with an omni-directional scanner antenna about 10' above the roof line of my house. I was fortunate to be able to borrow a GRE amp from a friend before I bought mine and when I hooked into my antenna line the world opened up! From my house I can now hear most of northern NJ. I can now also monitor several neighboring counties in NY as well as FDNY and NYPD. I've had no problems with overload in any of my radios (5 scanners hooked into the amp and then out to the antenna) with the amp on.

Unfortunately it isn't that easy to borrow one to see if it would help you but if you can, by all means, try it. Just keep an open mind, it all depends on your specific situation.