At 05:56 PM 03/03/07, you wrote: >Has anyone used a Kenwood TM-271A to make a repeater, I cannot find the >discriminator audio for this radio. Any help would be appreciated. > >Cory Lee >KC5EWJ
Why would you want to use a receiver with a super-wide front end for a repeater? Or a mobile radio with next to no heat sink as a repeater transmitter? While mobile radios can be used quite readily as a low-to-below average performance repeater receiver and you cannot use it as a repeater transmitter or link transmitter without due consideration to the normal mobile radio limitations on RF power and duty cycle. The average mobile was designed for a 10% to 15% transmit cycle (which means no more than 10 to 15 seconds out of each 100 seconds), and the radio will burn itself up if run in regular high-duty-cycle repeater service. Remember that the beauty of a repeater is that it is a device that allows one-to-many communications. As such, while any individual user may only transmit for 10 to 30 or even 60 seconds the repeater is transmitting for the entire conversation of all of the users. This is not to say that you can't transmit for three minutes, but the transmitter is going to get hot, and the longer it talks the hotter it gets. Some radios have power control circuitry that senses the transmitter heat sink temperature rise and turns the transmitter power down if you talk too much, but do you want a situation where your repeater transmitter goes into power shutdown on its own, in the middle of a conversation? You really don't want your repeater fading out during something important like a search and rescue operation, or even a 911 autopatch call. If you are going to build a repeater, do yourself a favor and get a radio designed as a repeater - something with multiple tuned circuits in the front end (i.e. designed for single channel operation), and a good sized heat sink. Mike WA6ILQ
