I am sorry, but if there available options for adjusting my PSR 500 for marginally decent performance on linear simulcast distortion, I would have saved money. I gave up and bought a 436 HP and never looked back. It was worth the money for me. Nothing worked on my local P25 system.
all of these guys have miles of trial and error on this problem, that is why we all have 436's. So take there advise, but there are a few more moves left out. first get a propagation map, and tweek when propagation is high. run your squelch almost ccw but never all the way. then direct your yagi to closest signal. also try scan with few talk groups and then on hold. then it will be easier to find the "sweet spot" usually not close to walls. also try sensorly map. for a real sweet spot but it won't be at your house.
Your scanner performance on simulcast P25 system suck because of your scanner hearing multiple transmitters or simulcast overlap. The 1's and 0's get all jumbled up to the scanner receiver.
What I found works for me is simple. Use less antenna. Connecting to the 20 foot stick on our 80 foot tower at work sucks on my scanner, but the diamond dual band antenna on my roof at 15 feet works much better. Trail an error will need to be done, but you need to do your best to keep your scanner from hearing more than one transmitter. If you live outside the simulcast system coverage area, this will be manageable. If you are right in the middle of it, it may be very difficult.
If you want to nuke simulcast distortion, it will cost you, big time. The G5 radio handles P25 simulcast distortion. It is a professional grade radio that costs a ton of money in comparison to our lower quality scanners.
I have a PSR500 and a BCD436HP. From my home location neither scanner can handle the Simulcast issues I have with the Cuyahoga County MARCS-IP system with their factory antennas.
After trying several suggestions from folks I found what works (for my location). While shopping at the local Micro Center store I spotted the Supersonic SC602 HDTV Antenna on sale for $9. Plus Micro Center had the antenna cable adapter I needed for the BNC connector.
The antenna is just a directional (like a yagi) desktop TV Antenna. I connected the antenna to my PSR500 and pointed it at the closest MARCS-IP tower and it worked, clear audio. So now I attach the SC602 to whichever scanner I plan on monitoring MARCS-IP with when I'm at home.
Just to be clear, I'm not saying you should run out and buy a SC602. It's not a universal fix. You'll need to have patients and try some things to find out what works best for you.