I just got my Garmin back with the new upgraded board that is suppose to stop the loss of tracking range caused by using a high powered radio close to the Garmin.
We had three Garmin astro 220 tracking 4 collars in central Florida just South of Perry, very flat with planted pines and cypress ponds. My roof mount antenna was not working so I used the regular antenna that comes with the unit. Both of my friends also used the regular antenna. We started losing siginal around 800-900 yards and at ½ mile none of the three Garmin units could pick up any of the collars.
So with the regular antenna our max tracking range last weekend was ½ mile.
I hear of people that get miles on a regular basis. I wonder if some units just pick up better or if the area you hunt makes a difference. (You don’t get any flatter than where we were hunting last weekend). My test was with 3 units and 4 collars so I believe it is a good sample of what you should expect in central Florida.
Also if you are having problems with your tracker there is some good info at
http://www.biggamehoundsmen.com/forum/viewtopic.php?f=20&t=8387&sid=638042f5bfd732c5563903a30d3e49b3&start=30