Do you have another scanner running at the same time ?
a. Could be your 2nd/3rd radio causing the interference, when it stops on a channel
b. Check with a second radio for the signal, hopefully not the same make/model
c. Sometimes the TX/RX sites go flacky, we have one on VHF here in Boston that
when the external Temp drops below 30 deg it kerchunks itself in analog
d. Same with a Remote RX Site, that kerchunks but sends DPL
Every couple of minutes, there is a key up on this frequency lasting about 10 seconds in analog mode, no PL. I know this frequency is listed as the State Dept. as a digital channel in the db, so who or what keeps keying up every 2-3 min?