CPerk - Programming the radio allows for a receive frequency and a transmit frequency. If you are programming a channel where you only have monitoring privileges, not transmit, (i.e.local sheriff), then just enter the receive frequency and leave the transmit frequency field blank. Once programmed, if you try to transmit on that channel, the radio will return a loud error beep to let you know it did not transmit. I also set the power to low on these monitor only channels just as a matter of practice.
Another example of monitor only channels are those with a continuing broadcast, such as the NOA weather frequencies. I have entered all of them just as described above, only entering the monitoring frequency (i.e. 162,400 or 162,550, etc) in the receive field and leave the transmit field blank. .
If you are programming for a simplex frequency on which you want to transmit, such as the VHF Call frequency of 146.520, then you must enter 146,520 twice, once in the receive field and once in the transmit field.
If you are programming a repeater, then you must enter a different receive frequency and a transmit frequency. An example in the two meter ham band would be 146.700 for the receive frequency and 146.100 for the transmit frequency. The software will automatically populate the transmit field once a receive frequency is entered. In my case, it is the same frequency as the receive value. I then manually change the transmit value if it is a repeater channel being programmed.