Gre PSR 500 Desense

Chevyman22360 · #1 (**permalink**) 10-21-2008, 11:02 PM

I have a GRE PSR 500 and use it mostly for mobile, which I have a NMO mount Larsen 150/450/800 antenna. What my problem is, the 450 Mhz is weak, where there is repeaters just a few miles away they are really static. I am wondering what I need to fix this problem. The antenna mount and connector is really good shape. I have really good reception on the 150-160 Mhz. Any ideas would be great. Thanks in advance.

K2QI · #2 (**permalink**) 10-21-2008, 11:14 PM

You and I have opposite problems. I get poor air band reception in my area, whereas 400mhz and up is strong.

In my case, I get what I assume is desense or overload of the air band frequencies; sometimes I get 5 bars but nothing but static on certain frequencies. It doesn't seem to help swapping antennas.

jambo · #3 (**permalink**) 10-21-2008, 11:15 PM

Quote:

Originally Posted by Chevyman22360

I have a GRE PSR 500 and use it mostly for mobile, which I have a NMO mount Larsen 150/450/800 antenna. What my problem is, the 450 Mhz is weak, where there is repeaters just a few miles away they are really static. I am wondering what I need to fix this problem. The antenna mount and connector is really good shape. I have really good reception on the 150-160 Mhz. Any ideas would be great. Thanks in advance.

What type of mount ?
Magnet mount, etc. ?
What system are you trying to receive?

Need these in order for people to help ya out..

Chevyman22360 · #4 (**permalink**) 10-21-2008, 11:32 PM

Quote:

Originally Posted by jambo

What type of mount ?
Magnet mount, etc. ?
What system are you trying to receive?

Need these in order for people to help ya out..

I have a NMO through hole mount, and basically just conventional frequencies.

Chevyman22360 · #5 (**permalink**) 10-23-2008, 07:50 AM

Anyone have any more ideas???

detroit780 · #6 (**permalink**) 10-23-2008, 08:39 AM

Quote:

Originally Posted by Chevyman22360

I have a GRE PSR 500 and use it mostly for mobile, which I have a NMO mount Larsen 150/450/800 antenna. What my problem is, the 450 Mhz is weak, where there is repeaters just a few miles away they are really static. I am wondering what I need to fix this problem. The antenna mount and connector is really good shape. I have really good reception on the 150-160 Mhz. Any ideas would be great. Thanks in advance.

Have you checked the SWR at the frequencies you have issues with? Maybe the antenna has a bad coil for 450MHz? Is there water in the NMO connector? Is there a short in the coax? Is the coax good?

Les

Chevyman22360 · #7 (**permalink**) 10-23-2008, 10:59 AM

Quote:

Originally Posted by detroit780

Have you checked the SWR at the frequencies you have issues with? Maybe the antenna has a bad coil for 450MHz? Is there water in the NMO connector? Is there a short in the coax? Is the coax good?

Les

I have not checked the SWR, not sure how to do that. Could be a bad coil, I do have another identical antenna I will swap and see if it improves. The coax is good, was a brand new installation a month ago.
Thanks for the ideas.

Highpockets · #8 (**permalink**) 10-23-2008, 11:11 AM

Quote:

Originally Posted by Chevyman22360

I have not checked the SWR, not sure how to do that. Could be a bad coil, I do have another identical antenna I will swap and see if it improves. The coax is good, was a brand new installation a month ago.
Thanks for the ideas.

If it rained, you still could have got water in the connector, just a thought!

Chevyman22360 · #9 (**permalink**) 10-23-2008, 11:14 AM

Quote:

Originally Posted by Highpockets

If it rained, you still could have got water in the connector, just a thought!

Are you talking about water where the antenna screws onto the NMO? That is dry, unless water in the coil? Not sure on that.

Highpockets · #10 (**permalink**) 10-23-2008, 11:16 AM

Quote:

Originally Posted by Chevyman22360

Are you talking about water where the antenna screws onto the NMO? That is dry, unless water in the coil? Not sure on that.

Yes, I have seen water in that area where is screws on, it was only a thought.

Tom_G · #11 (**permalink**) 10-23-2008, 11:59 AM

A couple things to think about...
Handheld radios are designed to be "HOT" receivers with a rubber duck antenna.
When you attach an external antenna with gain to a handheld radio it can overload easily.
The GRE/Radio Shack radios are especially sensitive the the VHF range.
I recommend trying the attenuator on those nearby UHF frequencies and see if that helps.
When a scanner gets overloaded it can either make the signal sound scratchy and distorted or actually sound weak. Kinda strange, but that is what I have seen.
When I turn the attenuator on, it takes the distortion right away and it then sounds clear as a bell. Thank God for channel specific attuation.

Let us know if that helps.....

Chevyman22360 · #12 (**permalink**) 10-23-2008, 07:20 PM

Quote:

Originally Posted by Tom_G

A couple things to think about...
Handheld radios are designed to be "HOT" receivers with a rubber duck antenna.
When you attach an external antenna with gain to a handheld radio it can overload easily.
The GRE/Radio Shack radios are especially sensitive the the VHF range.
I recommend trying the attenuator on those nearby UHF frequencies and see if that helps.
When a scanner gets overloaded it can either make the signal sound scratchy and distorted or actually sound weak. Kinda strange, but that is what I have seen.
When I turn the attenuator on, it takes the distortion right away and it then sounds clear as a bell. Thank God for channel specific attuation.

Let us know if that helps.....

I have tried the attenuator as the signal was active and then heard nothing after I pressed the attenuator button. It is hard for me to understand, the other day I was driving down the road and passed a truck that I had the frequency for and seen him talking on his radio and the signal was very week. His repeater was only 3-4 miles away. I know it is not my radio, I have a pro 96 that I use and same reception quality.