According to the RR Database, the Linn County Public Safety (Project 25) System is a simulcast system and as such can suffer from signal overload where signals that are too strong from multiple towers will cause much grief trying to pick them up on scanners. What's worse is that the "too strong signals" will give you all of the indications of having "too weak signals". Yes, too much signal is a bad thing!
First try turning on the attenuator for that system to reduce the amount of signal the scanner is getting. If that works, great. If not, you'll need to do things to help reduce your signal strength or focusing your scanner on picking up one and only one of the towers. Reducing the signal strength may be as simple as using an antenna that will do a worse job on the 800 MHz signals (try using the generic one that came with the scanner instead of the 800 MHz optimized one you're now using. You may also try adding a length of spare coax you have to reduce the signal. Failing those options, you may need to get a very directional 800 MHz antenna (typically a yagi) and pointing it at the various towers to see if you can isolate one. Note that this may not be the closest tower to you, but the one where all of the others are located in your antenna's null zones (basically off to the sides). I have one system here that has a very strong local tower where my solution is to run the scanner without any antenna at all on it.
n5ims,
I think I'm in the "sweet spot" for the area. With the PRO96, PRO106 and PRO197, I get very little distortion. But when I drive around town with the PRO96 and PRO106, I find lots of areas that have badly distorted signals. I have all the encrypted channes locked out, so I'm pretty certain it's really intermod. (I'm a retired airborne comm systems engineer by trade and a ham for more than 50 years, so I've had a little experience!).
I have tried the attenuation schemes and have used both the telescoping antenna supplied with the scanner and UHF rubber ducky as well as an outside discone and a 9dB gain 902 antenna that I normally use with a small 902 repeater.
The gent that started this thread has pretty much the same experience here in town and Tim-in-Tx has similar results in Pearland, TX.
I've looked at the control and voice frequencies on a spectrum analyzer and all of the Linn Cty channels are within a couple of dBs of each other at this location, but there are adjacent channel signals that are 10 dB or more higher. So I'm thinking that some of the problem may be the inability of the scanner receiver to reject the adjacent channel signal rather that problems with the simulcast system. There are some areas in town that do have severe problems with the simulcast system and have been fairly successful using small yagis to improve things. I have a 33 ele. 902 loop yagi that came off the tower last fall for some other antenna work. As soon as the wx gets decent, I will get it back on the stack and see what it does.
Appreciate your comments. It really looks as though there is something unique going on with the PRO2096.
73
Jim w0nkn
