For three days in a row I went to 2 different projects in 2 different areas of an adjacent county and after about 45 minutes to 1 hour I lose UHF from the T1M. The signal goes down to between 5% and 20% even within full view of the base less than 500 feet away. Yesterday I went back to the base and switched UHF frequencies and was able to work for another 30 minutes and it lost UHF again. Today went to a project in a different part of the county and kept the frequency I switched to yesterday and it went down to 5% after about 45 minutes. Would this be some type of interference? All 3 times this happens after about 45 minutes into the session.