GRE Super Amplifier

[IdleMonitor]

Just wondering what kind of power supply is needed for one of these aside from using a 9V battery.

I haven't used this in years but it worked well when it was in use.

I don't understand though what happened with it. It's like it has the opposite effect. When it's on it doesn't seem like it's working. Meaning it just blanks out a signal that it should reliably recieve. Then in the off position it works as normal like it wasn't even being used. Any suggestions?

I haven't opened it up in a while and even if I did I wouldn't understand the insides. Is there a chance something has blown inside?

I'd like to get it working again as they're hard to come by at a decent price if ya can find one.

 

[mancow]

Could be a bad amplifier transistor. I have the flat table top model and it calls for a 9v power supply.

 

[IdleMonitor]

That sounds like it could be it if it sounds like the symptoms of what could be wrong. How would I go about diagnosing this or getting it fixed?

As far as the power supply is. I know I can use a 9V battery. But for a plug in type of power supply what would I use?

Could be a bad amplifier transistor. I have the flat table top model and it calls for a 9v power supply.

 

[mancow]

A power supply providing 9 volts is all you need. You would need to be able to inject a signal and make sure it's being amplified. If not it could be anything from a failed power supply component, failed component in the signal path or just simply a bad amplifier transistor. Other than buying parts and shotgunning it I don't know how you will diagnose it without some knowledge and test equipment.

 

[dispatch235]

I have one of those somewhere, seems like it has a gain adjustment on it that can also be turned to negative to attenuate the signal.

 

[letarotor]

It could be that it's made for certain frequencies from the past that you might not be monitoring now? I have no idea what type of radio transmission's or systems are in your area? And I don't know how old the amp is either. I had one back in the 1980s from MFJ that was a 100% waste of money. It was supposed to be for the VHF Hi band but it did something similar to what you described yours is doing. Mine did this from the day I bought it.

Are you listening to any 700 / 800 MHz TRS traffic where you are at? And if you are, is the amp listed as working or covering that frequency band?

It does seem that when electronics sit around for a long time without getting used they many times do have the tendency to not work right. Sometimes the contacts oxidize or things like the battery connectors corrode. I've had a number of things go bad after not using them for a while. And they had worked just fine the last time I had use them before putting them away.

It's kind of hard to say what the problem might be without a little more detail

I'd say check which receiver you're using, make sure that the amp does cover the frequency bands you're trying to use it on, look inside and make sure the parts and connections look okay, and make sure that things like the signal being over amplified might not be causing you to miss traffic. It might need to be attenuated which takes away from even needing to use the amplifier then.

Good luck and I hope that you get things working the way year want them to.

Brian (COMMSCAN)

Sent from my SAMSUNG-SM-G930A using Tapatalk

 

[IdleMonitor]

Its 100 mhz - 1 Ghz so its wide banded.

It worked great for me when it was working. The only reason why I haven't used it in so long was cause it stopped working like it should and when I say a long time I'm meaning years. Like almost 10 years I haven't used it.

It's one of those items I've just had kicking around for so long in the junk pile. Everyone has one of those. [emoji14]

I'll take a pic of the insides tomorrow and post it here.

It could be that it's made for certain frequencies from the past that you might not be monitoring now? I have no idea what type of radio transmission's or systems are in your area? And I don't know how old the amp is either. I had one back in the 1980s from MFJ that was a 100% waste of money. It was supposed to be for the VHF Hi band but it did something similar to what you described yours is doing. Mine did this from the day I bought it.

Are you listening to any 700 / 800 MHz TRS traffic where you are at? And if you are, is the amp listed as working or covering that frequency band?

It does seem that when electronics sit around for a long time without getting used they many times do have the tendency to not work right. Sometimes the contacts oxidize or things like the battery connectors corrode. I've had a number of things go bad after not using them for a while. And they had worked just fine the last time I had use them before putting them away.

It's kind of hard to say what the problem might be without a little more detail

I'd say check which receiver you're using, make sure that the amp does cover the frequency bands you're trying to use it on, look inside and make sure the parts and connections look okay, and make sure that things like the signal being over amplified might not be causing you to miss traffic. It might need to be attenuated which takes away from even needing to use the amplifier then.

Good luck and I hope that you get things working the way year want them to.

Brian (COMMSCAN)

Sent from my SAMSUNG-SM-G930A using Tapatalk

 

[letarotor]

...It's one of those items I've just had kicking around for so long in the junk pile. Everyone has one of those. [emoji14]

Oh yeah, I can say I definitely have one of those and probably enough to make up two piles haha

Brian (COMMSCAN)

Sent from my SAMSUNG-SM-G930A using Tapatalk

 

[letarotor]

One thing I forgot to mention after I saw the photo was the gain control. Have you tried adjusting that to see if the signal starts coming in any better or worse? It looks like the pictures showed a 20db gain amp and maybe it's possible something like 10db might work better? Just an idea in case you haven't tried it

Brian (COMMSCAN)

Sent from my SAMSUNG-SM-G930A using Tapatalk

 

[IdleMonitor]

Ya I've done all that with it too.

I'll try testing it out again further tomorrow to see what I kind of results I get.

One thing I forgot to mention after I saw the photo was the gain control. Have you tried adjusting that to see if the signal starts coming in any better or worse? It looks like the pictures showed a 20db gain amp and maybe it's possible something like 10db might work better? Just an idea in case you haven't tried it

Brian (COMMSCAN)

Sent from my SAMSUNG-SM-G930A using Tapatalk

 

[iMONITOR]

There's a good chance it's overloading and desentizing your scanner rather than helping it.

 

[IdleMonitor]

I get what your saying it's almost like that. Like when I say listen to a control channel I get under regular conditions then when I turn it on I don't get it anymore regardless of the db gain adjustment.

There's a good chance it's overloading and desentizing your scanner rather than helping it.

 

[Tech792]

These are notorious for cold solder joints. I used these over the years and with any movement with rigid coax connected, there was a few solder joints that would always break. Try opening it up and do a good visual inspection.

 

[sibbley]

When using a 9 volt adapter you must have a 9 volt DC adapter using the correct polarity. See attached instructions for the unit.

 

[buddrousa]

Are you using it on the same scanner and the same antenna?
If you are trying to use it on one of the new Whistler scanners you may be overloading the receiver.
Are you in the same area if so have they built any new tower sites close to you?
Are you trying to hear the same system or did they change to a new system?

 

[IdleMonitor]

So I put a 9V in it to try it out again. Light comes on as it should.

But again hearing the opposite effect. Turn it to the bypass and I hear the signal come through. Turn it to the amp and nothing comes through.

There is definitely something wrong with it.

Has nothing to do with my antenna or radio or anything like this. Its definitely something in the unit itself that is making it not work like it should.

 

[IdleMonitor]

Here's a few more pics of the insides.

 

[iMONITOR]

Grove Enterprises marketed a preamp but discontinued it way before Grove went out of business, and of course GRE also discontinued their preamp prior to getting of the business. Scanner Master no longer sells preamps for scanners. Apparently as time went on and scanners improved, preamps were not really needed and that still stands today if not more than ever. If you feel your signal level is lacking it's more productive to buy a better antenna and/or mount it in a better location, preferably outside of the home and at a reasonable height clear of obstructions. You can't amplify a signal that's not there to begin with.

 

[trentbob]

Yep I have both the portable inline and the desktop model. Pre-digital scanner days like before 2003 I used them both and they worked on UHF - 2 and 800 megahertz with different adjustments for each.

Once the bc250 Etc and the pro 96 Etc came out in 2003 it didn't seem to work the same anymore and they are now in the museum in my closet.

I used the Radio Shack 9 volt converter and a 9-volt battery in the portable inline model.

 

[IdleMonitor]

I've got a Diamond D-130 discone up on the roof. All is good there. I actually do get majority of the signals that I'm after to be honest. But there are just a few that are still out there that I'm wanting to get. I know the signals are there. They're just below the threshold of being able to decode the control channel of the system I'm wanting to get. Only when certain conditions allow will I actually get a good enough signal on the system for it to actually decode and I can hear the transmissions.

This is only the first step really in trying some things to get the signals I want. I've had other discussion threads about what I'm wanting and discussion on antennas an such.