Could TG111 have some traffic encrypted? I heard some traffic on TG111 last night in the clear on Monticello site and Delafield site. A few times yesterday my BC996XT stops and displays TG111 with no audio, similar if the traffic is encrypted. Does this happen to anyone else or I may just be to far from the site. The site signal meter flucuates between 1 and 4 or 5 bars.
Anything is possible. Considering, though, that the only mention of that talkgroup has been a patch of analog State Patrol dispatch and no native system traffic, I would highly doubt that what you're seeing is encryption use.
Given that your signal strength is fluctuating that much I would suspect that is your root cause. What would be happening is the radio sees the channel grant when it happens to be receiving well so it displays the tgid and switches to the voice channel. But then the signal drops and it gets nothing more to decode.
How far away are you? It's likely that the channel grant is to a 152.xx frequency. If you are far enough away from the site a co-channel paging transmitter, or even near frequency, could be desensing your radio.
As a way of troubleshooting when it happens again hold on the talkgroup. Does it display a radio ID the entire time, or does it too disappear? If encryption is being used you would still see a radio ID even though there is no audio. If, however, the radio ID disappears and re-appears then the issue is just a very low signal strength that the radio is unable to decode.