A common issue. The apparatus at my fire station had radios installed that when the mic was in its hangar, there was no PL. everything on the frequency was heard. When the tech was asked why this is he explained it was to be able to monitor ALL the users of the system before transmitting so as not to transmit until the frequency was not being used. It made for a noisy cab when the mic was not in its hangar. (The hanger was either attached to chassis ground, common to the radio, or, if it was mounted on plastic or other material, where it was not attached to ground, a ground jumper wire was incorporated. This method had some removing the mic from the hangar, incorporating our PL, so they were not bothered by other usage of the frequency... a practice that usually ends up with the mic being keyed up unknowingly when placed on the seat, becoming lodged between the persons buttocks and the seat... getting keyed up! After a period of time we asked that the hangar function be reversed where the mic, while in the hangar incorporating our PL was the norm and instructed all to first listen for other traffic on the frequency when they pulled the mic from the hanger to transmit. To this day I’ve wondered why the tech was hooking up the mic hangers as “open” to all traffic. I guess the commercial world of radio usage dictated the practice where the public safety world of radio usage did not. Most ignored the instruction to first listen for traffic before transmitting unless it was another “fire” radio doing the talking. One thing appreciated by all was the quiet on-scene radio operations, by hanging the mic back in its hanger all the unwanted traffic was muted.
Our radio system was (and still is) using one of the same frequencies as the FDNY, a busy organization to say the least! And although we were out distance-wise better than the 70 mile rule of thumb, they still made their presence known! Not so much these days, I guess NYFD has moved off their VHF high band systems?
