Batboard

We have a Motorola XTL2500 setup in a cross band repeater. The problem is sometimes the radio will not TX or RX but remains powered on. We can power cycle the radio and it will work properly until it quits again. We have a midland VHF rackmount connected to the XTL 2500 800MHz through a controller. When keyed up the total current draw is about 18 amps on a 12 volt power supply. The power supply is rated for 16 amps 50percent duty cycle. Does the XTL 2500 radio have a low voltage shutdown with inhibits TX and RX? If that is not the case is there any other reason why this radio would inhibit TX and RX?

thanks
Lewismc

First of all, you should turn the power down on both of the radios. If you have any repeater type
service they are being used in, it doesn't take much to get them overheated from transmitting
too much. Most mobiles are designed to only transmit 5% of the time. When they get pressed
into some other application other than a normal mobile use, the TX duration will always exceed
the 5% duty. Thus the recommendation of turning down the power out.

Second, the power supply is of the same animal. If you try to pull more out of it than the normal
50% duty, it will start to drop in voltage and over heat. By dropping the TX power out on your
radios, you can resolve 2 problems at once. I would also measure the DC voltage right at the radio
to make sure you still have at least 13 volts. Radios do strange things on low voltage.

Third, if your controller doesn't have a TX time limit, I would set the radios you have so their
internal time out timers are set to no more than 2 minutes or less. This way they will not lock
on in TX.

Other than that have fun.

Jim

Lewismc wrote:We have a Motorola XTL2500 setup in a cross band repeater. The problem is sometimes the radio will not TX or RX but remains powered on. We can power cycle the radio and it will work properly until it quits again. We have a midland VHF rackmount connected to the XTL 2500 800MHz through a controller. When keyed up the total current draw is about 18 amps on a 12 volt power supply. The power supply is rated for 16 amps 50percent duty cycle. Does the XTL 2500 radio have a low voltage shutdown with inhibits TX and RX? If that is not the case is there any other reason why this radio would inhibit TX and RX?

thanks
Lewismc

I second everything that Jim said. Your power supply is almost definitely being overdriven. It would be a good practice to go with a supply that can handle at least 30% more than the peak load demands...25 amps in your case would suffice. Your supply is likely dropping in voltage just enough to cause the XTL to eventually 'lock up'.

Todd

Problem found. Seems we have had some power problems from our local power company and the backup power system had blown the fuse. we replaced the fuse and ordered a larger power supply. Problem has stopped since we replaced the fuse, but we will problably reduce the power output of the 800MHZ radio. thanks for your suggestions.