APX8500 Low Tx Power Issue??

[sullyc837]

Having issues with a couple APX8500's. Programmed a codeplug into the radio then tested Tx power, but when transmitting the control head went black all of the sudden then reset. Tried testing again and the power out was only about 20-30 watts. Ive seen it before where sometimes there wont be any power out at all. I've ran into this issue with the APX8500's before, and usually end up having to send the radio's into our supplier to have them fix the issue. The only description they give us of the issue is that they state it is a firmware issue.

Just wondering if anyone here on the site has ran into this issue as well, and if there is a fix to this? I cant find any information online concerning this issue. Would like to try and see if i can fix the issue myself before having to send these radio's in. Thanks!

 

[cifd64]

It is a firmware issue. Specifically with the 8500's. CH firmware and Radio firmware need to be R24 or better. This cleared up all of our power issues. Also, if you are planning on using a harris trunk system on this radio, you MUST run CPS R24 or better, with the firmware update.

 

[KG4INW]

Might not be your exact issue, but we've also noted that 8500s won't produce full power if just below 13.0 V. We used a variable power supply and the power would jump or drop (very quickly) 10 W while going from 12.9 and just below to above 13.0. It's been consistent with every model we've ever had on our bench and all levels of firmware. However, yes there have been a lot of bugs in the firmware that later releases have to fix.

 

[cifd64]

Which model? We had a similar issue with all types of 8500, from the standard mobile to the high power mobile repeater model. Of course, providing enough power to the radio is critical, we did the same test with an SPS-1820 and a much higher output supply. The radio would constantly reboot after the splash screen when powered up with a P25 Zone selected. When powered up with a conventional zone selected, no issues.

 

[Tech21]

Is the vehicle running you when you test it? The control head resetting when transmitting generally indicates that the radio is not getting enough current to the radio. Check you grounds and check all of your connections.