question

[station32]

why do they normally simulcast some talk groops on conventional freqs?

[gmclam]

There are dozens of reasons which depend on the entities involved. In my area, fire dispatch channels are simulcast on VHF and the local TRS. The fire tones to the stations only go out on VHF. I suspect 800 MHz receivers were not provided for the equipment which receives the tones.

In some cases it could be for mutual aid to an adjacent agency. Agency A is on a TRS while agency B next door is still on conventional frequencies. By putting agency B on the TRS, people in agency A can receive calls w/o the need for separate radios.

[wlmr]

Another big reason why has to do with the transition time from conventional frequencies to a trunked system. If you catch a trunked system just getting started with users it can be a good time to figure out what the trunked talkgroups are by seeing what conventional frequencies they are cross-connected with.

[station32]

Thanks,
joe

[REDave]

For the Fire service they will simulcast a TRS talk-group with a VHF or UHF channel is because they do not make an affordable TRS capable voice pager for the fire service.