Using awk:

awk -v start="20260603_080000" -v end="20260603_083000" '
  $1 >= start && $1 < end { print  }
' BOB_raw_20260602_191631.log | grep Hi
 
  
awk -v start="20260603_080000" -v end="20260603_083000" '
  $1 >= start && $1 < end { print  }
' BOB_raw_20260602_191631.log | grep 'TX LINK:'
 
  
awk -v start="20260603_080000" -v end="20260603_083000" '
  $1 >= start && $1 < end { print  }
' BOB_raw_20260602_191631.log | grep 'RX LINK:'